40731158 alternative pollinators native bees

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A Publication of ATTRANational Sustainable Agriculture Information Service 1-800-346-9140 www.attra.ncat.org

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(www.attra.ncat.org) is managed

by the National Center for Appro-

priate Technology (NCAT) and is

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our sustainable agri-

culture projects.

Contents

By Eric Mader, MaceVaughan, MatthewShepherd and ScottHoffman Black

The Xerces Societyfor InvertebrateConservationwww.xerces.org

Published 2010

This publication provides information and resources on how to plan for, protect and create habitat fornative bees in agricultural settings. Creating and preserving native bee habitat is a good risk manage-

ment strategy for farmers of specialty crops such as almonds, apples, blackberries, blueberries, cherries,

cranberries, pears, plums, squash, tomatoes and watermelons. Oil and biofuel crops requiring bee pol-

lination include canola and sunflower. Even meat and dairy industries are dependent on bee pollination

for the production of forage seed such as alfalfa and clover. In many cases, these native pollinators are,

on a bee-for-bee basis, more efficient than honey bees.

Alternative Pollinators:Native Bees

Introduction ..................... 1Case study: Gardensof Goodness Farm .......... 2

Native bee biology ........ 3

Native bee habitat ......... 4

Native bees as croppollinators ......................... 4

Assessing native beehabitat on farms ............. 5

Pollinator-friendlyfarming .............................. 6

Providing alternative

forage ................................. 8Creating artificialnest sites .......................... 11

Common nativebees ................................... 17

Case study:The alkali bee .................19

Appendix 1: Plants tosupport native bees ....20

Appendix 2: Additionalresources .........................23

References ......................25

Introduction

Worldwide, there are an estimated20,000 species of bees (Michener,2000), with approximately 4,000

species native to the United States (Win-free et. al., 2007). Te non-native Europeanhoney bee (Apis mellifera) is the most impor-tant crop pollinator in the United States.However, because of disease and other fac-tors the number of managed honey beehives in the United States has declined by50 percent since 1950 (NRC, 2007). Duringthis same period, the amount of crop acre-

age requiring bee pollination has continuedto grow. Tis makes native pollinators evenmore important to the future of agriculture.

Native bees provide free pollinationservices and are often specialized for

foraging on particular flowers, suchas squash, berries or orchard crops.his specialization results in moreeffi cient pollination and the produc-tion of larger and more abundant fruitfrom certain crops (epedino, 1981;Bosch and Kemp, 2001; Javorek et. al.,2002). Te pollination done by native

bees contributes an estimated $3 billionworth of crop production annually to the U.S.economy (Losey and Vaughan, 2006).

Mason bee on berberis. Photo by

USDA-ARS, Jack Dykinga.

Mining bee carrying load of yellow pollen entering

nest. Photo by Matthew Shepherd, The Xerces Society.


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Page 2 ATTRA Alternative Pollinators: Native Bees

Case study: Gardens of Goodness Farm

Pollinator conservation is essential to Barb and Jim Lindemanns Gardens of Goodness farm nearMadison, Wis.

As a diversified organic farm with more than 40 antique apple varieties, as well as peach, cherry andquince trees, blueberry and raspberry plants and numerous bee-pollinated vegetables, Gardens ofGoodness has a highly varied abundance of crops blooming throughout the growing season.

Gardens of Goodness has high pollination demands, but the farm is surrounded by miles of

conventional corn and soybean farms and a small housing development of manicured lawns hardly the best bee habitat. To compensate for their situation the Lindemanns have steadilyimproved their farm for bees by adding supplemental floral sources, enhancing nest sites andlearning to farm without pesticides.

The result is a farm that is always buzzing with the activity of countless wild bees as well as benefi-cial insects that help keep pest populations in check. On any given day during the growing seasonit is not unusual to see dozens of bee species on the farm. Bright metallic green sweat bees swirl

around the berry crops,ground-nesting miningbees and wood-nestingmason bees fly among thefruit trees, and huge lum-

bering bumble bees slowlymove between the rows oftomato transplants.

This abundance of bees isnot by chance. The Linde-manns have taken severalspecific steps to encour-age bees. They addedred clover, white cloverand Siberian squill to theorchard understory toprovide nectar and pollen

before and after the fruittrees are in bloom. Also,non-aggressive weedslike dandelion and violetare tolerated, resulting in a

colorful, flower-rich ground cover. In addition to providing nectar and pollen for bees, these plantshelp trap the spores of apple scab (a fungal disease harbored in leaf litter) close to the ground wherewind and rain cannot splash the spores up into the tree canopy and cause new infections.

Nest sites for bees have been enhanced on the farm by providing nest blocks for mason andleafcutter bees. Naturally occurring patches of bare ground where ground-nesting bees mightbe present are maintained and plastic mulch is not used in the vegetable row crops.

Because the Lindermanns have a diversity of crops and rotate their row crops regularly, pest popu-

lations rarely reach problematic levels and pesticides are rarely needed. Apples, which are theirlargest crop, are processed into cider rather than fresh marketed so that minor cosmetic damageby pest insects can be tolerated. The Lindemanns make every effort to control the few crop peststhat do occur with pheromone and sticky traps rather than chemicals. Even chemical fertilizers areunnecessary for the Lindemanns. Instead, they use a composted invasive lake weed, which theyreceived free through a partnership with their local watershed district, as their main fertilizer.

All of these practices, many of which began as attempts to conserve pollinators, have added upto a productive business with an enthusiastic community-supported agriculture (CSA) programand farm stand customer base.

Gardens of Goodness orchard. Photo by Eric Mader, The Xerces Society.


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Page 3ATTRAwww.attra.ncat.org

Native Bee BiologyNative bees come in a wide range of colorsand sizes, from tiny sweat bees less than aquarter of an inch long to bumble bees overan inch in length. While some of these spe-cies may look like the familiar image of abee with hairy yellow and black stripes, theymay also be dark brown, black or metallic

green and blue, with stripes of many colors.Most are solitary, with each female creatingand provisioning her nest without the sup-port of a caste system of workers. Most areunlikely to sting (Shepherd et. al., 2003).

Te common names for native bees oftenreflect their nest building habits: miner, car-penter, mason or plasterer. Other namesdepict behavioral traits. For example, sweatbees drink salty perspiration to acquire nutri-tionally important minerals.

About 70 percent of native bees excavateunderground nests (Potts et. al., 2005). Soli-tary bees dig narrow tunnels leading to a seriesof brood chambers, each one provisioned witha mixture of pollen and nectar and each hold-ing a single egg (Michener, 2000).

About 30 percent of bees nest in wood tun-nels, usually pre-existing holes such as thosemade by wood-boring beetles, but some willchew out the center of pithy twigs (Michener,2000). Females of these wood-nesting beescreate a line of brood cells, often using mate-rials such as leaf pieces or mud as partitionsbetween cells (Ooole and Raw, 1999).

In the case of both ground-nesting andwood-nesting bees, once the nest is complete,

the mother bee generally dies. Her offspringwill remain in the nest, passing through theegg, larva and pupa stages before emergingas an adult to renew the cycle.

For some species this life cycle may progressover a matter of weeks, resulting in a secondgeneration of bees in a single season. A fewspecies may remain dormant for over a year.

Most solitary bees however complete this lifecycle over the course of a full year.

Native bees often only live for a few weeksas actively flying adults. Tey mate immedi-ately upon emergence and the females beginnesting. Tey lay relatively few eggs com-pared to other insects, with a single femaleoften laying less than 50 eggs before shedies. Male bees do not live long beyond mat-ing, they do not collect pollen and have littlevalue as pollinators.

While most of these wood-nesting andground-nesting bees are solitary, some aregregarious, preferring to nest near others,a behavior that allows large aggregations to

Mounds of excavated soil surround the entrance to

bee nests. Photo by Eric Mader, The Xerces Society.

Snag with beetle tunnels now occupied for bee nests.Photo by Matthew Shepherd, The Xerces Society.

Inside of reed stem showing pollen mass and eggs. Photo by G. Neuenswonder,

USDA-ARS.

Related ATTRAPublications

Farmscaping

to EnhanceBiological Control

Organic IPM

Field Guide

Tree Fruits

Organic Production

Overview

Applying

the Principles

of Sustainable

Farming


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develop in favorable locations. Only a fewtunnel and ground-nesting bee species everdevelop truly social colonies, and often suchbehavior is environmentally dependent withsome bees being social in one situation andbeing solitary in another (Michener, 2000).

Te one group of strictly social bees nativeto the United States is the group of approxi-

mately 45 bumble bee species (Kearns andTompson, 2001). Bumble bees live in a colony

with a caste system of workers, males and asingle egg-laying queen. Within this socialstructure, bumble bees share the labor offoraging and rearing their young.

Similar to honey bees, bumble bees constructa wax comb; however, this comb is not a sym-metrical series of hexagonal cells, but rather isan abstract configuration of round wax pots,some containing brood and some containing

small amounts of pollen or nectar.

Bumble bees nest in cavities such as aban-doned rodent burrows, brush piles and grasstussocks (McFrederick and LeBuhn, 2006).Te colony grows through three or four gen-erations and, depending on the species, mayhave several hundred workers at the peak inmid-summer. Unlike honey bees, bumblebee colonies do not survive over the winter.

Native bee habitatHabitat for native bees has two major com-ponents: a place for the nest and flowers to

forage. As detailed above, thenest site can be bare groundor a snag. Te flowers can benative wildflowers or non-native weeds. Most bees arenttoo choosy; if they can reachthe nectar or gather pollen, theycan supply their nest. Some

bees, however, are very choosyand will only gather pollenfrom a small number of plantspecies. In extreme cases, thebee may be restricted to just asingle plant species. Social bees

with a long-lived colony, suchas bumble bees, need flowersblooming throughout the sea-son. Solitary bees usually have

a much shorter active period, often no morethan five or six weeks, and have life cyclessynchronized with the blooming of preferredflower species.

Te two habitat components need to beclose enough together so that the bees canfly between them. Te flight distance of abee varies with the size of the bee. Small

sweat bees and mining bees may not flymore than 200 or 300 yards from nest toforage area (Greenleaf et. al., 2007). Largebees (bumble bees, for example) can crossa mile or more of inhospitable, flower-lesslandscape to forage. But however large thebee, if it has to fly too far the effort beginsto outweigh the benefits and the bee mayeither find somewhere else to nest or notsurvive in the landscape.

A third factor that influences habitat is insec-

ticide exposure. o thrive, bees need minimalexposure to pesticides.

Native bees ascrop pollinatorsAmong the food crops requiring bee pollina-tion are almonds, apples, blackberries, blue-berries, cherries, cranberries, pears, plums,squash, tomatoes and watermelons. Oil

Farm pond with snag and surrounding

vegetation. Photo by Mace Vaughan, The

Xerces Society.

Wildflowers planted to create on-farm habitat. Photo

by Katharina Ullmann, The Xerces Society.


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and biofuel crops requiring bee pollinationinclude canola and sunflower. Even meat anddairy industries are dependent on bee pollina-tion for the production of forage seed such asalfalfa and clover.

Producers of these crops should considerthe needs of native bees in their farm man-agement because these insects may provideincreasing yields and farm profit, and reducereliance on rented honey bees. Native beesalso provide an insurance policy if rentalhoney bees are prohibitively expensive or dif-ficult to obtain.

Native bee ef f iciency

Many native bee species are more effectivethan honey bees at pollinating flowers on abee-for-bee basis. For example, according toU. S. Department of Agriculture researchers,only 250 female blue orchard bees (Osmialignaria) are required to effectively pollinatean acre of apples. Te is the equivalent ser-vice of one to two honey bees hives, eachcontaining 15,000 to 20,000 workers (Boschand Kemp, 2001).

Te reason for this increased effi ciency is themason bees greater tolerance for cold andwet weather. In addition, the foraging behav-ior is different in native bees than in honeybees. For example, individual honey beeworkers specialize in the collection of eitherpollen or nectar. Nectar-foraging honey beesoften never contact the anthers (pollen-pro-

ducing structures) in apples, unlike masonbees that must collect both pollen and nec-tar (Bosch and Kemp, 2001).

Alfalfa flowers provide another example ofnative bee effi ciency. Te stamen (the struc-ture holding the anthers) of alfalfa flowersis held under tension by two flower pet-als, and springs forward with force whenreleased by a visiting bee. Tis triggeringdiscourages many bees, including honeybees, who learn to avoid being hit by the sta-

men by approaching the flower from behind,where they can gather nectar but not pollen.Te alkali bee (Nomia melanderi), a nativeground-nesting bee, is not discouraged bythis unusual flower structure and is a majorpollinator of alfalfa seed in some westernstates (Mader et. al., 2010).

Some native bees are highly effi cient becausethey specialize in one type of flower. Squashbees (genus Peponapis), for example, pri-marily visit flowers from the squash family

(epedino, 1981). Female squash bees oftenstart foraging before dawn and the maleseven spend the night in squash flowers.

Another effi ciency of native bees is the pro-cess ofbuzz pollination. Bumble bees inparticular are notable for their ability tograsp a flower and vigorously vibrate theirflight muscles, releasing pollen from theanthers. Tis behavior is very important forsome plants such as blueberries, cranberries,tomatoes and peppers, all of which release

pollen from pores within the anthers (simi-lar to salt being shaken from a salt shaker)(Mader et. al., 2010).

Assessing native beehabitat on farmsMany growers may already have an abun-dance of habitat for native pollinators onor near their land. Having semi-natural or

Yellow-faced bumble bee on raspberry flower. Photo

by Mace Vaughan, The Xerces Society.

Yellow-faced bumble bee approaching tomato flower.

Photo by Mace Vaughan, The Xerces Society.

M

any

native

bee

species are moreeffective than honey

bees at pollinating

flowers on a bee-for-

bee basis.


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natural habitat availablesignificantly increasespollinator populations(Kremen et. al., 2004and Williams and Kre-men, 2007). Linear hab-itats along field edges,hedgerows and drainage

ditches offer both nest-ing and foraging sites(Carvell et. al., 2004).

Woodlots, conservationareas, utility easements,farm roads and otheruntilled areas may alsocontain good habitat.Often, marginal areasthat are less fit for cropsmay be managed as pol-linator habitat (Moran-

din and Winston, 2006).Here are some tips on

recognizing specific resources so that theycan be factored into farm planning.

Existing plant compositionWhen assessing pollen and nectar resources,it is important to look at all of the plantson and around a farm. Tese plants includeinsect-pollinated crops, as well as the flowers even weeds in buffer areas, forest edges,roadsides, natural areas, fallow fields andmore. Insect-pollinated crops may supplyabundant forage for short periods of time.However, for pollinators to be most produc-tive, nectar and pollen resources are neededoutside the period of crop bloom.

As long as a plant is not invasive, consider let-ting some of the native or non-native weedsand wildflowers bloom. For example, dande-lions, clover and other non-native plants are

often good pollinator plants in orchards.Keep in mind that small bees may only flya couple hundred yards, while large bees,such as bumble bees, can forage a mile ormore from their nest (Greenleaf et. al.,2007). Terefore, taken together, a diversityof flowering crops, wild plants on field mar-gins and plants up to a half-mile away onadjacent land can provide the sequentially

blooming supply of flowers necessary tosupport resident pollinators.

Existing nest sitesLook for nest sites around the property.Nests of ground-nesting bees are likely tooccur in semi-bare patches of soil. Wood-nesting bees will be in snags or shrubs with

soft-centered twigs (Michener, 2000). Bum-ble bees may be nesting in old rodent bur-rows or brush piles.

Most bees are active on warm sunny days,from mid-morning through the afternoon.Some, however, may be active early in themorning (for example, squash bees), whileothers will continue flying late in the evening(bumble bees). Anywhere from one to thou-sands of bees may be present at a nest siteand they may be as small as a medium-sized

ant (less than a quarter inch) to larger than ahoney bee (three-quarters of an inch).

In the case of ground-nesting solitary bees,the nest entrance will be visible only duringthe season the adults are active, the timingof which varies from species to species. Tenest entrances appear as small holes in theground, often with piles of excavated soilaround the entrance. In some cases, theymay resemble an ant nest, although oftenwith a larger entrance hole.

Pollinator-friendly farmingIn addition to conserving the food and nestsources of native bees, you can take an activerole in protecting bees through the adoptionof pollinator-safe farming practices. Whileinsecticides are an obvious threat to bees,other farm operations or disturbances suchas burning and tilling can also cause harm.

Minimizing pesticide useInsecticides not only kill pollinators (Johan-sen, 1977), but sub-lethal doses can affect theirforaging and nesting behaviors, often prevent-ing plant pollination and bee reproduction(Tompson, 2003; Decourtye et. al., 2004;and Desneaux et. al., 2007). Herbicides cankill plants that pollinators depend on whencrops are not in bloom, thus reducing the

Trackside wildflowers provide useful habitat.



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amount of forage available (Kremen et. al.,2002 and scharntke et. al., 2005).

In general, while pesticide labels may listhazards to honey bees, potential dangers tonative bees are often not listed. For example,many native bees are much smaller in sizethan honey bees and are affected by lowerdoses. Also, honey bee colonies may be cov-

ered or moved from a field, whereas wildnative bees will continue to forage and nestin spray areas.

If pesticides cannot be avoided, they shouldbe applied directly on target plants to pre-vent drift. Broad-spectrum chemicals shouldbe avoided if at all possible. In addition toactive ingredients, consider the formulationof pesticides; generally dusts and fine pow-ders that may become trapped in the pol-len-collecting hairs of bees and consequently

fed to developing larvae are more dangerousthan liquid formulations (Vaughan et. al.,2007).

Crops should not be sprayed while in bloom.Nighttime spraying, when bees are not for-aging, is another way to reduce bee mortal-ity. Periods of low temperatures may alsobe good for spraying because many beesare less active. However, the residual toxic-ity of many pesticides tends to last longerin cool temperatures. For example, dewynights may cause an insecticide to remainwet on the foliage and be more toxic to beesthe following morning, so exercise caution(Vaughan et. al., 2007 and Johansen andMayer, 1990).

Spray drift presents another threat to for-aging native bees. Drift can occur either asspray droplets or vapors, as happens whena volatile liquid changes to a gas. Factorsaffecting drift include temperature (includ-ing temperature inversions), wind, applica-tion method, equipment settings and sprayformulation (Ozkan, 2000).

Spray application methods and equipmentsettings also strongly influence the potentialfor drift. Since small droplets are most likelyto drift long distances, aerial applicationsand mist blowers should be avoided. Stan-dard boom sprayers should be operated at thelowest effective pressure and with the nozzlesset as low as possible. For example, drop noz-zles can be used to deliver insecticide withinthe crop canopy where it is less likely to becarried by wind currents. Regardless of the

chemical or type of application equipmentused, sprayers should be properly calibratedto ensure that excess amounts of pesticideare not applied (Ozkan, 2000).

Alternatives to conventional insecticidesinclude the use of selective products that tar-get a narrow range of insects, such as Bacil-lus thuringiensis(Bt) for moth caterpillars,although even these products can be detri-mental when they drift. Other alternativesfor some pests include bug vacuums, phero-

mones for mating disruption and kaolin claybarriers for fruit crops. Several ARA pub-lications are available to assist farmers withimplementing non-chemical pest controlalternatives. See the ARABiorationals:Ecological Pest Management Database, avail-able at www.attra.ncat.org, for informa-tion on specific product and pests. Finally,remember that many of the habitat featuresthat support pollinators will also host benefi-cial insects that help control pests naturally,

reducing the need for pesticides.

Minimizing the impact ofmowing, haying, burningor grazingGrazing, haying, mowing and fire can havedamaging effects on pollinators (Black et.al., 2008). Historically, there were suffi-cient areas of diverse vegetation to supportCalibrating sprayer nozzles. Photo by USDA-ARS.

I

f pesticides

cannot be

avoided, they

should be applieddirectly on target

plants to prevent drift.


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populations of habitat specific pollinators.However, now that many of these areas existonly as fragments in larger agricultural land-

scapes, consideration of pollinators is neededto ensure healthy populations.

Studies suggest that less than one-fifth ofpollinator habitat should be burned, mowedor hayed at any one time in order to protectdormant pollinators, foraging adults andother wildlife. Tis will allow for re-colo-nization of the disturbed area from nearbyundisturbed refugia (Hartley et. al., 2007).In order to maximize foraging and nest-ing opportunities, maintenance activitiesshould be avoided while plants are in flower(Smallidge and Leopold, 1997). Ideally,mowing or haying should be done only inthe fall or winter.

Grazing can be a valuable tool. However,grazing is usually only beneficial at low tomoderate levels and when the site is grazedfor a short period followed by ample recov-ery time and when it has been planned tosuit the local site conditions.

Protecting bee nestsNative bees often nest in inconspicuous loca-tions. It is important to retain as many natu-rally occurring sites as possible and to createnew ones where appropriate.

Ground-nesting bees seldom nest in richsoils, so poor quality sand or loamy sandsoils may provide fine sites. In order to protect

nest sites of ground-nesting bees, tilling andflood-irrigating areas of bare or partially bareground that may be occupied by nesting beesshould be avoided (Shuler et. al., 2005 andVaughan et. al., 2007).

Grazing such areas can also disturb groundnests. And fumigants for the control ofsoilborne crop pathogens (such as Verticil-

lium wilt), or covering large areas with plas-tic mulch can be detrimental to beneficialground-nesting insects such as bees.

Weed control alternatives to tillage that aresafer for ground-nesting bees include the useof selective crop herbicides, flame-weedersand hooded sprayers for between row herbi-cide applications.

Leaving patches of un-mowed grass in whichrodents can nest will create future nest sites

for bumble bees. Bunch grasses tend to pro-vide better nesting habitat than sod-formingvarieties. Structural landscape features suchas brush and stone piles also provide nestinghabitat for bumble bees.

For wood-nesting bees, allow snags and deadtrees to stand as long as they do not pose arisk to property or people.

Providing alternative forageUndeveloped areas on and close to farms canserve as long-term refuge for native wild pol-linators. Protecting, enhancing or provid-ing habitat is the best way to conserve native

Contrast in vegetation due to grazing. Photo by Irv Cole, USDA-NRCS.

Areas of brushy vegetation will offer nest sites forbumble bees. Photo by Mace Vaughan,

The Xerces Society.


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pollinators and, at the same time, providepollen and nectar resources that supportlocal honey bees. On farms with suffi cient

natural habitat, native pollinators can pro-vide all of the pollination for some crops.

Such habitat can take the form of designatedpollinator meadows (bee pastures), orchardunderstory plantings, hedgerows and wind-breaks with flowering trees and shrubs,riparian and rangeland revegetation efforts,flowering cover crops and green manures,and other similar efforts.

Where possible, locally native plants are

often preferred for their ease of establish-ment, greater wildlife value and their co-evolution with native pollinators (Kearns et.al., 1998). Non-native plants may be suitableon disturbed sites, for specialty uses suchas cover cropping and where native plants

are not available. Mixtures of native andnon-native plants are also possible, as long asnon-native species are not invasive.

Distance from fieldsTe typical foraging distance of native beesranges from about 200 yards to a half-mile,

with larger species able to fly farther. o be

of greatest benefit to crop production, areasof natural habitat should be within a half-mile of an insect-pollinated crop. Ideally,potential nesting sites would be even closer(a couple of hundred yards), in order toincrease the number of small bees reaching acrop in bloom.

Size of habitatStudies in California demonstrate thataround 30 percent of the land within three-quarters of a mile of a field should be in nat-ural habitat in order to provide full pollina-tion for watermelon (Kremen et. al., 2004).Similarly, studies in Canada have shownthat in the absence of honey bees canolafarmers can increase their income becauseof increased pollination by native bees if 30percent of their farmland is left in naturalhabitat (Morandin and Winston, 2006). Ina mixed landscape straddling the New Jer-sey-Pennsylvania border, crops of tomatoes,

peppers and watermelons all received highvisitation from native bees because of thepresence of woodlands (up to 60 percent ofthe land within 1.25 miles of a field) andother habitat areas between fields (Winfreeet. al., 2008).

Scientists and growers are still learning abouthow much habitat is needed for other crops.In general, a sound strategy is to make hab-itat patches as large as feasible within theconstraints of a farm and to create as manypatches as possible. Larger areas of habi-tat ensure a greater likelihood that forage,nest sites and nest building materials will beavailable within the bees flight range andthroughout the flight season.

Habitat corridorsCultivated fields have replaced most of thenatural habitat in many modern agricultural

The USDA-NRCS and other agencies have advisors

who can help. Photo by USDA-ARS.

Field edge hedgerow, with natural area is background;

nearby habitat supports pollinator populations.


o be of

greatest

benefit to

crop production,areas of natural

habitat should be

within a half-mile

of an insect-

pollinated crop.


10/28


landscapes, resulting in significant distances

between areas of habitat that harbor nativepollinators. Continuous, permanent stripsof vegetation can link these patches andpotentially increase the rate at which polli-nators and other wildlife colonize new areasof habitat near agricultural fields. Tey alsomay serve to grab the attention of bees fly-ing across the landscape. Tese long narrowhabitat features can aesthetically enhancedrainage ditches, fencerows and roadsides.Increased connectivity, particularly between

larger areas of natural habitat, will bring agreater overall benefit.

Select plants thatcomplement the cropMost bees emerge before crops come into

bloom and manybee species are stillactive afterwardthe crop bloomperiod. Terefore,

plenty of forageshould be availablebefore and aftera particular cropcomes into bloom.his timing willattract bees andensure that theycan successfullyraise many young.

If a farm already grows a diversity of crops,the timing of flowers produced by non-cropplants is less of a concern and the crops them-selves help provide a sequence of bloom.

For example, vegetable farmers might allowsome salad, root and herb crops to bolt. Inaddition to pollinators, the predators and para-sitoids of many pests are attracted to the flow-ers of plants like dill, cilantro, arugula, chervil,chicory, mustards, carrots and radishes.

Finally, avoid plants that serve as alternatepest and disease hosts and plants that arelikely to become weeds in the primary crop.

Technical andf inancial assistanceechnical support and financial incentive

programs are available to landowners whoare interested in setting aside, enhancing orrestoring some of their land for pollinatorhabitat in the United States.

Several USDA programs administeredthrough the Natural Resources Conserva-tion Service (NRCS) provide planning assis-tance and financial support for the creationof new wildlife habitat, and in some casesactual rental payments to growers. Amongthe most well known of these programs isthe Conservation Reserve Program (CRP),

which pays landowners for the conversionof marginal cropland to a less intensive use(Vaughan and Skinner, 2009).

Historically these programs were intendedto reduce erosion, protect water quality andprovide habitat for wildlife such as pheasantsand whitetail deer. Language in the 2008Farm Bill, however, has made the promotionand conservation of pollinator habitat a pri-

ority among USDA conservation programs.

In many states, three programs, the WildlifeHabitat Incentives Program (WHIP), theEnvironmental Quality Incentives Program(EQIP) and the Conservation StewardshipProgram (CSP), offer specific technical andfinancial support for pollinator conserva-tion (usually native wildflower plantings) onfarms (Vaughan and Skinner, 2009).

Hedgerow and woodlots close to fields (within flight range) support native pollinator

populations. Photo by Scott Bauer, USDA-ARS.

Insectary plants used within field as crop row-end

markers. Photo by Matthew Shepherd, The Xerces

Society.


11/28


In many cases, these programs can also beused for multiple purposes. For example,plants attractive to pollinators could be usedin a grassed waterway with the primary objec-tive of stabilizing a hillside against erosion.

For information about these conserva-tion programs, contact your nearest USDANRCS office. Locations can be found at

www.nrcs.usda.gov.

Creating artificial nest sitesTere are a number of ways to provide nest-ing sites for different kinds of native bees,from drilled wooden blocks to bundlesof reeds to sand pits or adobe bricks(Shepherd et. al., 2003 and Vaughan andBlack, 2006). Generally, increasing nestingopportunities will increase bee numbers.However, to be sustainable, artificial nests

need to be maintained over time to preventthe buildup of parasites and disease (Boschand Kemp, 2001 and Mader et. al., 2010).

Nesting sites forground-nesting beeshe precise conditions needed by mostground-nesting bees are not well known.Some species nest in the ground at the baseof plants, and others prefer smooth, packed

bare ground. You can create conditionssuitable to a variety of species by maximiz-ing areas of untilled ground and preparingdesignated areas of bare soil.

Soil piles might be constructed with soilexcavated from drainage ditches or silt traps.Different species of bees prefer different soilconditions, although research shows that

many bees prefer sandy or sandy loam soils.For a more formal look, make raised sandbeds edged with lumber or bricks. Alterna-tively, you can create a sandpit by simplydigging a pit 2 or 3 feet deep, and fill it withfine-grained, pale-colored sand or a sand-loam mixture (Vaughan and Black, 2006).

hese nesting areas can be as small as 1to 2 square feet, but preferably should beseveral yards on each side. Your site can belevel or sloping, but it should be well-drained,open and sunny. Place a few rocks in thecleared area; they will retain heat and beeswill bask on them (Shepherd et. al., 2003).

Colonization of these nest sites will dependon which bees are already present in thearea, their successful reproduction and pop-ulation growth and the suitability of othernearby sites.

Maintenance of nests

for ground-nesting beesIn general, ground-nest sites should receivedirect sunlight and dense vegetation shouldbe removed regularly by mowing, hand

weeding or spot treating with herbicide, tomake sure that some patches of bare groundare accessible. Once constructed, try notto walk or drive across the site. Rememberthat buried under the ground are possiblyhundreds of bees.

Nests for wood-nesting beesCommercially produced bee blocks, consist-ing of a wood block drilled with a series ofdead-end holes, are now widely available.Tese types of bee nests were initially devel-oped in the 1960s by alfalfa seed producersin the western United States to attract andmanage large numbers of the non-nativealfalfa leafcutter bee (Megachile rotundata).

Drilled wood blocks offer nesting opportunities for

many native bees. Photo by Katharina Ullmann,

The Xerces Society.

o be

sustainable,

artificial

nests need to bemaintained over

time to prevent the

buildup of parasites

and disease.


12/28


More recently they have been modified to

manage the blue orchard bee (Osmia lignaria),a bee that is active only in the spring and willnot pollinate later-flowering fruits and vege-tables. Consequently, all of the nest tunnelsare a uniform size and depth, which may beeither too large or too small for many otherspecies. Nest blocks with a greater diversity ofhole sizes and depths are necessary to attract avariety of bees that are active throughout theyear (Mader et. al., 2010).

Under the best circumstances these nests canattract large numbers of cavity-nesting beesand boost their local populations. However,because these nests concentrate bee popula-tions in unnaturally large numbers in a smallspace, they can become infested with para-sites and disease spores after several seasons.

Without regular sanitation or the phasingout of nest materials, these parasites and dis-eases threaten long-term pollinator health

wherever they are used. Because contami-nated nest blocks left unattended in thelandscape continue to attract wild bees fromthe surrounding area, they have the potentialto do harm (Mader et. al., 2010). Only withproper management can these nests main-tain healthy bee populations indefinitely.

Wooden blocksUse preservative-free dimensional lumber toconstruct wooden nest blocks. A four-by-fouris appropriate for blocks with smaller diame-ter holes. A four-by-six works for blocks withlarger diameter holes.

In one side, drill a series of nest holes ofappropriate sizes and depths. Nesting holesshould be between 332 and 38 inch indiameter. Holes of 1 4 inch or less in diame-ter should be 3 to 5 inches deep. Holes largerthan 14 inch should be 5 to 6 inches deep(Bosch and Kemp, 2001 and Shepherd et.al., 2003). Te female bee controls the gen-der of her offspring and usually finishes thenest with a few male brood cells. A deeperhole ensures space for more female brood.

Occupied nest block

showing nest seals of

neatly cut leaf pieces.

Photo by Eric Mader,

The Xerces Society.

Nests made from stacks

of grooved boards

can be opened easily

to clean the tunnels.

Photo by Eric Mader,

The Xerces Society.

Bold markings help

bees find their nest

tunnels. Photo by

Eric Mader, The

Xerces Society.

Blue orchard bee nests in cherry orchard. Photo by

G. Neuenswonder, USDA-ARS.


13/28


Te holes should be about 34 inch from cen-ter to center and no closer than that to theedges of the block. Attach a backing boardif you drill all the way through your block,because bees will not use a drilled hole thatis open at both ends. With smaller diame-ter drill bits, you may not be able to achievethe 3-inch minimum recommended depth.

If that is the case, simply drill as deep as youcan; bees that use holes of smaller diame-ters will often nest successfully in ones thatarent as deep.

Bees may avoid a rough interior, so yourholes should be perpendicular to the woodsgrain and drilled with a sharp bit. You canbuy paper straws to line the holes, although itmay be hard to find straws that fit all diame-ters. One solution is to wrap your own paperstraws out of parchment or newspaper using

dowels of various diameters that match theinside diameters of your drilled holes. Paintthe outer tips of the straws black to helpattract bees (Bosch and Kemp, 2001).

Te exterior of the block can be any color,although there is some anecdotal evidencethat bees are most attracted to dark blocks,

which can be achieved by lightly charringthe front surface with a propane torch.Whatever the color, bees are likely to use theblock as long as the holes are of appropri-

ate diameters and depths, and hung in anappropriate location. As a final step, you canattach an overhanging roof to provide addi-tional shelter from the rain.

Colonization is often more successful whenblocks are attached to a large visible landmarksuch as a building. Te actual height fromthe ground does not much matter, althoughif the nest is too low (less than a few feet),rain splash may dampen it and vegetationmay cover it. Nest blocks should be hung in aprotected location where they receive strongindirect sunlight. Direct sunshine in themorning will help bees warm themselves upto flight temperature, so you may wish toplace nests facing east, allowing the morningsun to fall on the entrance holes. Direct sun-light later in the day can be detrimental, caus-ing eggs or developing brood to overheat anddie (Shepherd et. al., 2003).

Since these types of nests mimic trees fre-quented by woodpeckers, do not be surprisedif one finds your nest. o protect againstdamage, you might want to store your nestsin an unheated building at the end of theseason. Alternatively, you can protect nestsover the winter by surrounding them withhardware cloth. Be sure to remove the cloth

before nesting resumes because hardwarecloth can disorient nesting bees and damagetheir wings (Mader et. al., 2010).

Stem bundlesIn addition to wooden blocks, artificial nestscan be constructed with bundles of reed, tea-sel, cup plant or bamboo cut so that a natu-ral node forms the inner wall of the tunnel.

Bamboo nest units

in orchard. Photo by

Eric Mader, The

Xerces Society.

A plastic bucket makes a convenient

container for bamboo or reed stems.

Photo by Eric Mader, The Xerces Society.

Blue orchard bee closing nest in

bamboo tube. Photo by Mace Vaughan,

The Xerces Society.


14/28


Cut each stem below the nodes (usuallyindicated by a ridge) to create a handful oftubes, each with one open end. Strap thetubes together into a tight bundle with wire,string or tape, making certain that the closedends of the stems are all at the same end ofthe bundle. A variation on this is to tightlypack the stems open ends out into a tincan, paper milk carton, square plastic buck-ets or short section of PVC pipe. Te bun-dles should be placed in a sheltered location(such as the side of a barn or garden shed)with the stems horizontal to the ground.

Adobe blocksSome solitary bees nest in cracks or cavi-ties in soft sandstone and dry exposed soilembankments. Some of these species, such asAnthophora abrupta andAnthophora urbana,will excavate tunnels in cliff sides by wetting

the hard soil surface with water or nectar tosoften it. Tese two species are importantvisitors of some fruit and vegetable crops andare quite common in the southeastern andsouthwestern United States, respectively.

o attract these species, adobe bricks canserve as the equivalent of a wooden nestblock. Such bricks can sometimes be pur-chased, in which case you can increase theirattractiveness to bees by drilling nestingholes following the size recommendations

listed above for wood blocks.Adobe blocks can also be easily made whereclay soils are common. o create one, half-filla large bucket with clay soil, and then fill thebucket with water. Stir the mixture togetherto create a muddy slurry and allow it to set-tle. Remove any sticks or debris floating onthe surface and slowly pour off most of thewater. Finally, pour the remaining sedimentinto a mold (such as a wooden box or smallStyrofoam cooler), and allow it to dry for

several days or weeks. Before it completelydries, you can make several 1-inch indenta-tions, using the diameter guidelines above,to make it more attractive to bees.

Mount the brick, either singularly or ina stack. Adobe will not hold up well in wetclimates and many need sheltering fromrain. You might want to supply a shallow

water source near your bricks to help beesexcavate their nests.

Nesting materialsIn addition to nesting holes, different spe-cies need different materials to build theirbrood cells, which consist of intricate wallsthat partition off the tunnel into a seriesof separate chambers. Tese partitions sealthe nest entrances and protect the broodfrom predators.

Depending on the species, these walls maybe constructed of mud, plant resins, pieces ofleaf, flower petals, fine pebbles and even cel-lophane-like glandular secretions (Oooleand Raw, 1999). It is likely that these mate-rials are already present in your area, but ifyou provide a diversity of native plants andsome mud puddles, you can guarantee it.

Keep in mind that bees may not fill theentire length of a tunnel with cells, or they

may die before an entire length of a cavity isfilled. For these reasons it can be diffi cult totell if a nest tunnel is occupied by just look-ing for sealed entrances.

Maintenance of tunnel-nestsWhether your nests are wooden blocks, twigbundles or other materials, nests will needroutine management in order to be sustain-able. Nests also need regular replacement to

prevent the build-up of parasites and diseasesthat affect the developing brood.

Te hardest of these to control is chalkbrood(Ascosphaera spp.), a fungal disease. Severalspecies of the fungi exist among tunnel-nest-ing bees, all of which are different from thechalkbrood disease that attacks honey bees.Bee larvae become infested with diseasespores through contaminated pollen, eithercollected from a flower by the mother beeor accidentally spread when the mother bee

emerges from a contaminated nest cavity(Mader et. al., 2010).

C

halkbrood

spores

germinate

inside the gut of thedeveloping larva,

producing hyphae

that eventually

penetrate the

gut wall, killing

the larva.

Inside of bamboo stem showing clean, healthy

cocoons. Photo by Eric Mader, The Xerces Society.


15/28


After they are ingested, the chalkbroodspores germinate inside the gut of thedeveloping larva, producing long filaments(hyphae) that eventually penetrate the gutwall, killing the larva. As the filaments con-tinue to grow below the skin of the deceasedlarva, they eventually produce dark-coloredspores. Te appearance of infested cadav-ers thus varies from white to grey to blackdepending on the stage of fungal develop-ment. Tese brittle cadavers pose a hazard

to bees deeper within the nest block that,upon emergence, must climb over or chewthrough the spore-infested cell to escape thenest. Bees that emerge under these circum-stances have a high likelihood of spreadingthe spores to their own offspring. Similarly,bees searching for new unoccupied nest tun-nels in which to lay their eggs frequentlyinvestigate, and often select, previously usedtunnels. Over time, chalkbrood spores arespread throughout a nest block in this way(Mader et. al., 2010).

Along with chalkbrood, pollen mites in thegenus Chaetodactylus can be a persistentproblem in nest blocks that are in continu-ous use for several seasons. Unlike the mitesthat attack honey bees, pollen mites do notfeed on the hemolymph (blood) of the bee.Instead, pollen mites feed on the pollen pro-vision, causing the developing bee larva tostarve (Mader et. al., 2010).

Adult pollen mites are usually white in color

and measure about 500 microns in width,about the size of the period at the end of thissentence. As with chalkbrood, adult beesmay accidentally pick up mites at flowers

while foraging, or from climbing throughor investigating contaminated nest cavities.Migratory nymph stages of the mites clingto a bees hairs and are transported backto the nest, where they feed on the pollenprovision and reproduce rapidly. In a single

provisioned cell, mite numbers can quicklyclimb into the thousands. While pollenmites usually cannot break through cell par-titions, they can persist for many months

without food, until a bee deeper within thenest emerges from the tunnel and breaks thepartition walls, allowing them to escape. Itis not uncommon to see bees emerging from

infested nest blocks covered with so manymigratory mite nymphs that they havediffi culty flying (Mader et. al., 2010).

o reduce these parasite and disease problems,we recommend one of three approaches:

1. Te holes of wood nest blocks can be linedwith tight-fitting removable paper straws.At the end of the nesting season (autumn),the straws are gently removed, placed ina ventilated container and stored eitherin a refrigerator or an unheated barn orgarage. Te nest block is then disinfectedby submerging it in a bleach-water solu-tion (1:2 ratio) for a few minutes. In thespring, fill the block with clean, previ-ously unused paper straws and return it toits location. Te old straws (with bees inthem) are placed alongside the nest block,and the bees are allowed to emerge natu-rally. When the old straws are empty, theyare disposed of.

2. Wood and adobe nest blocks and stembundles can be phased out every two yearsby placing the blocks and bundles insidea dark container, such as a light-proof

wooden box or even a sealed milk cartonthat has been spray painted black to reducelight infiltration. A single 3/8-inch exithole is drilled in the bottom of the light-proof container and the entire contrap-tion is hung adjacent to a new, previouslyunused nest block or stem bundle. As beesemerge from the old nest, they are attractedto the light of the exit hole and emerge tofind the new one hanging nearby. Te oldnest block or stem bundle is then disposedof at the end of the season.

3. he last alternative is to create multi-ple small nest blocks or stem bundles

with only a few nest tunnels (4 to 6)and hang them at intervals of 25 feet ormore. Tis prevents the unnaturally high

Inside of bamboo stem showing nest infected with

chalkbrood. Photo by Eric Mader, The Xerces Society.

P

ollen mites

feed on

the pollen

provision, causingthe developing bee

larva to starve.


16/28


populations of bees found at nest blockswith many holes and mimics natural con-ditions of limited, spatially separated nestsites. Tese smaller nests also decomposemore rapidly and can be allowed to simplydeteriorate naturally, while new small nestsare added to the landscape periodically.

Nest boxes for bumble beesUnlike solitary bees, which can be very par-ticular about tunnel diameters, bumble beesare flexible in their nesting needs. All theywant is a warm, dry cavity, roughly the sizeof a shoebox (Shepherd et. al., 2003). Artifi-cial nests can be constructed to attract bum-ble bees, but occupancy is typically extremelylow often far less than 25 percent.

A simple wooden bumble bee box can bemade from preservative-free lumber. An

appropriate size will have internal dimen-sions of about 7 inches high by 7 inches

wide and 7 inches long. Drill a few ventila-tion holes on the upper sides of the box (nearthe roof) and cover with window screen todeter ants. Also drill some drainage holes inthe bottom. Make an entrance tunnel from34-inch diameter plastic pipe and fill thebox with soft bedding material, such as shortlengths of soft unraveled string, dry straw orupholsterers cotton (do not use cotton balls,

as the fibers become tangled in the bees

legs). Te box must be weathertight; if thenest gets damp, the larvae may become toocold and mold and fungus will grow.

Place the nest in a dry, undisturbed areathat has some obvious landmarks (a fencepost, rock or building) to aid bee naviga-tion; these landmarks are important to beesreturning from foraging. Nesting boxes that

are at ground level or slightly buried (eitherwith soil or straw) are the most attractive toqueens of many species. Boxes placed on thesurface should be level and stable. If you areburying your box, extend the entrance pipeso it gently slopes up to the surface and clearthe vegetation from an area a few inchesaround where the pipe surfaces.

Te best time to install a bumble bee nestbox is in early spring, when the first queens

have emerged from hibernation and aresearching for a nest site; in many areas, thisis when the willows first start blooming.

Maintenance ofbumble bee nestsBumble bee nests require little maintenance.

Watch your boxes through the spring andearly summer. Any above-ground boxes thatare unoccupied by late July can be removed,cleaned and put into storage until the fol-

lowing spring. Tis is not vital, and if youhave a lot of boxes on a large site it maynot be practical. In late fall or early winterinspect all the boxes that have been occu-pied. Remove the old nests, clean them andmake any repairs. Cleaning the boxes witha bleach-water solution (1:2 ratio) will helpreduce parasites and diseases in the nests.he following spring, add fresh nestingmaterial to all the boxes.

Commercial nativebee productionRecently, many people have become inter-ested in the blue orchard bee (Osmia lig-naria), also called the orchard mason bee,as a garden and orchard pollinator. Manythousands of mason bee nesting blocks aresold each year in the United States, alongwith hundreds of thousands of blue orchard

Bumble bee nest box showing construction. Photo by Matthew Shepherd, The

Xerces Society.


17/28


bees. Tis interest has greatly raised publicawareness about the importance of pollina-tors; however, it is important to rememberthat raising large numbers of a single spe-cies (bee-ranching) is a different objectivethan the conservation of diverse species ofwild pollinators.

As mason beekeeping has increased in popu-

larity, important questions are being askedabout the risks associated with the nation-wide shipment of blue orchard bees by com-mercial producers. In fact, there are twodistinct subspecies of the blue orchard bee:Osmia lignaria propinqua in western North

America and Osmia lignaria lignaria in theeast. Te species is rare in the Great Plainsregion, although some intermediate speci-mens have been collected.

Most commercial producers of the blue orchardbee are located in the Pacific Northwest, wherethey rear the locally native western subspe-cies (Mader et. al., 2010). Unfortunately, thebees these producers raise are then marketednationwide, resulting in the frequent shipmentof locally non-native bees to the eastern UnitedStates. Te potential ecological consequencesof the western blue orchard bee hybridizingwith its eastern subspecies are unknown. Simi-larly, these shipments have the potential tointroduce locally non-native parasites anddiseases. For the consumer, there is anothersignificant drawback. Te western bees maynot develop in sync with local conditions,resulting in poor establishment and poorperformance as pollinators. Te net resultis that people purchasing blue orchard beesover the Internet or through garden catalogsmay be doing more to harm their local pol-linator populations than to help them andnot be getting the pollination they paid for.

Similarly, the package bumble bee industry,which provides farmers with live bumble beecolonies for crop pollination, currently onlyproduces a single eastern bumble bee spe-cies, Bombus impatiens. Tis species is thenshipped nationwide, in a situation similarto the blue orchard bee, often far beyond itsnative range. Many bumble bee scientists nowbelieve that these commercially producedbumble bees are responsible for the introduction

of one or more diseases which have decimatedseveral bumble bee species, even causing thepotential extinction of one species, Bombusfranklini(Franklins bumble bee) (Evans et.al., 2008).

here is an enormous need for managedagricultural pollinators in this country, butit critical not to import non-local bees, espe-

cially near wild areas, even if the bees arerepresented as being the same species as localbees. Te alternatives are to either developlocal commercial sources of bees that arenative to your region or to rear already

widely established non-native species, suchas honey bees or the alfalfa leafcutter bee, asmanaged pollinators.

Common native beesGlobally, bees are grouped into seven fam-

ilies. Six of these have species in North America, although only five, the Colleti-dae, Andrenidae, Halic-tidae, Megachilidae and

Apidae, are commonlyencountered. Te familyMelittidae is representedonly by about 60 gener-ally uncommon species inNorth America (Michener,2000 and Ooole and

Raw, 1999).

Colletidae:Polyester beesBees in the family Collet-idae are highly varied inappearance and have fewcommon features. One fea-ture consistent to all col-letid bees is that their tongue has a branchedtip. Colletids secrete a plastic-like substance(hence the familys common name) that theyuse to waterproof their brood cells. Tis allowsthe bees to nest in periodically flooded areassuch as stream banks. Te two genera mostfrequently seen are Colletesand Hylaeus.

Andrenidae: Mining bees With just over 1,400 hundred species inNorth America, Andrenidae is the most

Metallic green sweat bee. Photo by Susan Ellis,

Bugwood.org.


18/28


diverse family of bees on the continent.Andrenidae are abundant in the spring and,as their common name indicates, excavatenests in the ground. Te huge majority ofspecies in this family are solitary. A smallnumber of species are communal, with sev-eral females sharing a nest entrance but eachexcavating and provisioning their own brood

cells. Tey generally nest in flat or gentlysloping sites and may form aggregationswith tens of thousands of bees nesting in asmall area. Commonly encountered generaareAndrena and Perdita.

Halictidae: sweat beesHalictidae are among themost frequently encoun-tered bees during sum-mer. Although this fam-

ily includes brightlycolored metallic bees, themajority of halictids aredrably colored and small.Most Halictidae exca-vate nests in the ground,though some nest in rot-ting wood. he genusLasioglossum includes the

whole gamut of socialbehaviors from solitaryto semi-social (nests con-structed by a group ofbees in which one is theegg-laying queen). hebright greenAgapostemonis communal; a dozen ormore females may share anest entrance, but under-ground each bee cre-ates her own brood cells.Other common genera inthis family are Halictus,

Augochlora, Nomia andAugochlorella.

Megachilidae: Leafcutterand mason beesMegachilidae is one of the easiest families torecognize because its members dont carry pol-len on their legs. Instead, they have rows ofstiff hairs on the underside of their abdomen

into which they pack dry pollen for trans-port back to the nest. Te great majority of

megachild bees nest in existing cavities aboveground (beetle tunnels in snags, crevices inrocks) and collect items such as leaf piecesor wet soil to divide the nesting tunnel intobrood cells. Tis family includes the com-monly managed leafcutter (Megachile) andmason bees (Osmia).

Apidae: Bumble, carpenterand other beesTe Apidae is an immensely diverse familythat includes bumble bees (Bombus) as wellas a wide range of less well-known yet fre-quently encountered groups such as the dig-ger (Anthophora), squash (Peponapis) andsunflower (Svastra) bees. Given the diversityof its genera, it will come as no surprise thatthe Apidae displays the full range of nest-ing behaviors from solitary to social and hasspecies that nest in the ground, in wood and

Sweat bee foraging in California poppy. Photo

by Matthew Shepherd, The Xerces Society.

Metallic green sweat bee. Photo by Susan Ellis,

Bugwood.org.

Leafcutter bee foraging on pea flower. Photo by

Whitney Cranshaw, Colorado State University.

Courtesy of Bugwood.org.

Leafcutter bee resting on leaf. Photo by Joseph Berger,

Bugwood.org.


19/28


Case study:The alkali bee

The requirementsof one ground-nesting species, thealkali bee (Nomiamelanderi), are sowell understood

that artificial nestingsites are created toprovide reliable croppollination for alfalfain eastern Washing-ton and Idaho.

Forage producersfirst recognized thealkali bees affi nityfor alfalfa blossomsin the 1940s. The alkali ground-nesting bee isnative to arid regions west of the Rocky Moun-

tains. Following the development of manage-ment techniques in the late 1950s, growersusing the alkali bee have produced astoundingyields of up to 2,400 pounds of cleaned seed peracre this in the normally unproductive desertregions of the Great Basin.

In the wild, the alkali bee excavates nests in thecrusted-over soils of alkali flats. In these areas,the capillary action of high water tables drawswater to the soil surface where salt crystals andminerals are deposited as the water evaporates.These minerals form a thin crust limiting furtherevaporation and maintaining a moist nestingenvironment in the otherwise arid region of thebees native range. Under optimal conditionsa single cubic footof these alkalinesoils may containup to 50 nests.

Because they areground nesters,alkali bees cannotbe easily transportedand their usefulnessis confined to arid

locations typicallyflat alkaline desertsoils. Within theseplayas (or salt flats),individual bee nestsare usually located inthe upper 8 inches ofsoil and consist of tunnel entrances with a seriesof brood chambers located below the surface.

Common eastern bumble bee nectaring on purple

coneflower. Photo by David Cappaert, Michigan State

University. Courtesy of Bugwood.org.

Digger bee at entrance turret to nest in steep bank-

side. Photo by Scott Bauer, USDA-ARS.

Male longhorn bee nectaring on cosmos. Photo by

Mace Vaughan, The Xerces Society.

in old rodent burrows. Other genera in thisfamily include Xylocopa, Ceratina, Diadasia,Eucera andMelissodes.

Adult alkali bee on ground. Photo by James L. Cane,

USDA-ARS.

Alkali bee bed. Photo by James L. Cane, USDA-ARS.


20/28


The alkali bee is susceptible to habitat loss fromgrazing and off-road vehicle use and now isuncommon in parts of its original range. How-ever, artificially constructed soil beds continueto provide some habitat in the alfalfa seed-pro-duction regions of the Great Basin and PacificNorthwest.

These artificial beds should be constructed insilty loam soils with no more than 7 percent clay.Beds typically consist of an excavated trench,usually 2 to 3 feet deep, which is then lined withan impermeable layer (pond liner, plastic sheet-ing or bentonite clay). A system of perforateddrain pipes set in layers of gravel is installed,including vertical standpipes every 50 feet, andthe trench is refilled with lightly compacted soil.When finished the bed should be slightly ele-vated so that rain water does not pool on top.As water is added to the standpipes, moisture

will rise to the surface and create a firm layer ofsalt that seals in soil moisture and slows furtherevaporation of water from the bed.

Maintaining the correct soil moisture wherebees are actively nesting is critical and, as

necessary, water can be added through thestandpipes. If excessive soil drying becomes aproblem during the nesting season, bee bedscan be shaded with either nursery shade clothor military surplus camouflage netting sus-pended above the bed on permanent posts.

Alkali bees may find the artificial bed if othernatural or managed nest sites are locatedwithin a mile or so. However, the bed mayhave to be stocked with bees, either as adultsor as larvae. Blocks of undisturbed soil thatmeasure 1 cubic foot are cut from establishedbeds and inserted in the new one. This is nor-mally performed during the winter, when thelarvae are inactive.

There is little published information regard-ing optimal bed size for managed alkali beepopulations. Beds of around an acre in sizemay produce thousands or even millions of

bees. In fact, in some areas grower cooper-atives manage these community beds andsince alkali bees may forage up to 5 miles ormore, the bees provide pollination servicesfor multiple farms.

One of the challenges that bees face in agricultural land-scapes is a lack of season-long food sources. Large mono-cultures of bee-pollinated crops like almond, canola orwatermelon may provide a few weeks of abundant food,but a lack of adjacent wild plants blooming before andafter the main crop can result in a feast-or-famine situa-tion that cannot support healthy pollinator numbers.

Diverse wildflower plantings adjacent to cropland canprovide the floral diversity to support resident pollinators

(Williams and Kremen, 2007). As a general rule, farmers

who want to conserve bees should provide a minimum

of three plant species that bloom at any time during

the growing season, including spring, summer and fall

(Frankie et. al., 2002).

Te plants you should choose vary from region to region.

Some common plants that support a diversity of bee

species are included in the following tables.

Appendix 1: Plants to support native bees

NATIVE WILDFLOWERS

Plant Bloom time Native range

Common Name Genus Name Mar Apr May Jun Jul Aug Sep OctNorth-east

South-east

Mid-west

Moun-tain

North-west

South-west

Aster Symphyotrichum x x x x x x

Beardtongue Penstemon x x x x x x

Beebalm Monarda x x x x x x

Blanketflower Gaillardia x x x x x x

Blazingstar Liatris x x x

Case study: The alkali bee, continued from pg. 19


21/28




South-east

Mid-west

Moun-tain

North-west

South-west

California poppy Eschscholzia x x

Deerweed Lotus x

Culvers root Veronicastrum x x x

Eryngo Eryngium x x x x x x

Figwort Scrophularia x x x x x x

Fireweed Chamerion x x x x x

Hyssop Agastache x x x x x x

Goldenrod Solidago x x x x x x

Hayfield tar-weed

Hemizonia x x

Ironweed Veronia x x

Ithurieals spear Triteleia x x

Joe Pye weed Eupatorium x x x

Lobelia Lobelia x x x x x x

Lupine Lupinus x x x x x x

Milkweed Asclepias x x x x x x

Mountain mint Pycnanthemum x x x

Prairie clover Dalea x x x

Purpleconeflower

Echinacea x x

Rabbitbrush Chrysothamnus x x x

Rod wirelettuce Stephanomeria x x

Rosinweed Silphium x x x

Scorpionweed Phacelia x x x

Sneezeweed Helenium x x x

Spiderflower Cleome x x x

Spiderwort Tradescantia x x x xSunflower Helianthus x x x x x x

Vinegarweed Trichostema x x

Waterleaf Hydrophyllum x x x x x

Westernrosinweed

Calycadenia x x

Wild buckwheat Eriogonum x x x

Wild indigo Baptisia x x x

Wild geranium Geranium x x x x x x

Wingstem Verbbesina x x x

NATIVE TREES and SHRUBSPlant Bloom time Native range


South-east

Mid-west

Moun-tain

North-west

South-west

Baccharis Baccharis x x

Basswood Tilia x x x

Black locust Robinia x x x x x x

Blueberry Vaccinium x x x x x

Buckwheat tree Cliftonia x


22/28




South-east

Mid-west

Moun-tain

North-west

South-west

Chamise Adenostoma x

False indigo Amorpha x x x x x x

Madrone Arbutus x x

Manzanita Arctostaphylos x x

Magnolia Magnolia x

Ocean spray Holodiscus x x x

Oregon grape Mahonia x

Plum Prunus x x x x x x

Redbud Cercis x x x x x

Rhododendron Rhododendron x x x

Rose Rosa x x x x x x

Serviceberry Amelanchier x x x x x x

Steeplebush Spirea x x x x x

Sourwood Oxydendrum x

Toyon Heteromeles x

Tupelo Nyssa xWild lilac Ceanothus x x x x x x

Willow Salix x x x x x x

Yerba santa Eriodictyon x

NON-NATIVE GARDEN PLANTS


Common Name Genus Name Mar Apr May Jun Jul Aug Sep Oct North-east

South-east

Mid-west

Moun-tain

North-west

South-west

Basil Ocimum x x x x x x

Borage Borago x x x x x x

Catmint Nepeta x x x x x xCosmos Cosmos x x x x x x

Lavender Lavandula x x x x

Marjoram Origanum x x x x x x

Mexican sun-flower

Tithonia x x x x x x

Mint Mentha x x x x x x

Rosemary Rosmarinus x x

Russian sage Perovskia x x x x x x

Stonecrop Sedum x x x x x x

Squill Scilla x x

AGRONOMIC BEE PASTURE PLANTS



South-east

Mid-west

Moun-tain

North-west

South-west

Alfalfa Medicago x x x x x x

Buckwheat Fagopyrum x x x x x x

Mustard Brassica x x x x x x

Clover Trifolum x x x x x x

Radish Raphanus x x x x x x


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ARA National Sustainable AgricultureInformation ServiceP.O. Box 3657Fayetteville, AR 727021-800-346-9140

www.attra.ncat.orgARA provides information and other technicalassistance to farmers, ranchers, Extension agents,educators and others involved in sustainable agriculturein the United States. ARA is a project developedand run by the National Center for Appropriateechnology.

Agrecol2918 Agriculture Dr.Madison, WI 53718(608) 226-2544www.agrecol.comA producer of native prairie seed, Agrecol specializes ingrasses and wildflowers native to the northern tall grassprairie. Agrecol has experience in natural area restora-tion. Many of their seed mixes are suitable for pollinatorconservation projects.

Applewood Seed5380 Vivian StreetArvada, CO 80002(303) 431-7333

www.applewoodseed.comA wholesale supplier of wildflower seed for the westernUnited States.

Beediverse641 Claremont St.Coquitlam, BCCanada V3J 351-800-794-2144www.beediverse.com

Based in British Columbia, Bee Diverse offers a varietyof backyard blue orchard bee nests for sale, along withinformational books and videos.

Custom Paper ubes, Inc.

P.O. Box 44187Cleveland, OH44144-01871-800-766-2527www.custompapertubes.com

Provides fabricated-to-order paper tubes as solitary beenesting materials.

Entomo-Logic21323 232nd St. SE.Monroe, WA 98272-89821-360-863-8547

www.entomologic.comA Washington-based company providing the Westernsubspecies of the blue orchard bee, as well as mason beenests. Teir bees are inspected for parasites and diseasesbefore shipment.

Ernst Conservation Seed9006 Mercer PikeMeadville, PA 163351-800-873-3321www.ernstseed.com A vendor of native wildflowers, wildflower seed and

native trees for the eastern and southeastern United States.

Granite Seed1697 West 2100North Lehi, Utah 840431-801-768-4422www.graniteseed.com A large producer and vendor of native wildflower seedfor the Intermountain West, based in Utah.



South-east

Mid-west

Moun-tain

North-west

South-west

Partridge pea Chamaecrista x x x

Sweet clover Melilotus x x x x x x

Sweat vetch Hedysarum x x x

Vetch Vicia x x x x x x

For more information on pollinator conservation,including in-depth resources on all of the topics

Appendix 2: Additional resources

mentioned above, please go to:www.xerces.org/pollinator-conservation


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International Pollination Systems16645 Plum Rd.Caldwell, ID 83605(208) 990-1390www.pollination.com

Provides consultant services, supplies and breeding stockof various bee species for commercial orchards and fieldcrop growers.

JFNew708 Roosevelt RoadWalkerton, IN 46574(574) 586-3400www.jfnew.com

A native plant nursery and ecological consulting firmbased in Indiana. JFNew offers over 355 plant speciesincluding tall grass prairie plants (both seeds and plugs),as well as native trees. Many of their plants are suitablefor pollinator conservation projects.

Jonesville Paper ube Corporation540 Beck St.PO Box 39Jonesville, MI 49250(517) 849-9963www.papertube.com

A custom cardboard and paper tube manufacturer,Jonesville Paper ube has extensive experience providingmaterials for mason bee nests. Te company provides freesample materials on request.

Knox Cellars

25724 NE 10th St.Sammamish, WA 98074(206) 849-5065www.knoxcellars.com

A Washington-based company providing the Westernsubspecies of the blue orchard bee and mason bee nests.

Mason Bee Homes2460 Oakes Rd.Black Creek, BCCanada V9J 1J1www.masonbeehomes.com

Sells small, backyard-style mason bee houses.

Osmia.comwww.osmia.com

A Web site selling the Western subspecies of the blueorchard bee; based in Utah.

Pollinator Paradise31140 Circle Dr.Parma, ID 83660www.pollinatorparadise.com A manufacturer of leafcutter and mason bee nest blocks.

Te Pollinator Paradise Web site has extensive informa-

tional articles on leafcutter and mason bee management.

Pollinator Partnershipwww.pollinator.org

Te Pollinator Partnership brings together diverse orga-nizations to promote pollinator conservation in NorthAmerica. Te Web site offers many resources.

Prairie NurseryPO Box 306Westfield, WI 539641-800-Gro-Wild

www.prairienursery.com A Wisconsin-based producer of native tall grass prairie

seeds and flats of live plants.

Star SeedNorth Highway 14PO Box 504Beloit, KS 674201-800-782-7611www.gostarseed.com

A producer of western and midwestern wildflower seedappropriate for pollinator conservation efforts.

Te Xerces Society4828 SE Hawthorne Blvd.Portland, OR 97215(503) 232-6639www.xerces.org

Te Xerces Societys pollinator program works with farmers,land managers and public agencies to promote the conserva-tion of native pollinators. Te Xerces Society produces manypublications on how to protect, restore and enhance habitatfor pollinators (includingFarming for Bees and the

Pollinator Conservation Handbook). Te Xerces Societyalso provides training events including workshops, farmwalks and seminars and direct technical support togovernment agencies and farm industries.


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Black, S. H., N. Hodges, M. Vaughan, and M. Shep-herd. 2008. Pollinators in Natural Areas: A Primer onHabitat Management. 8 pp. Portland: Xerces Societyfor Invertebrate Conservation. www.xerces.org/pubs_merch/Managing_Habitat_for_Pollinators.htm

Bosch, J. and W. Kemp. 2001. How to Manage the

Blue Orchard Bee as an Orchard Pollinator. 88 pp.Beltsville: Sustainable Agriculture Network. www.sare.org/publications/bee/blue_orchard_bee.pdf

Carvell, C., W. R. Meek, R. P. Pywell, and M.Nowakowski. 2004. Te response of foraging bumble-bees to successional changes in newly created arablefield margins. Biological Conservation 118:327-339.

Decourtye, A., J. Devillers, E. Genecque, K. LeMenach, H. Budzinski, S. Cluzeau, and M. H.Pham-Delegue. 2004. Comparative sublethal toxicity

of nine pesticides on olfactory performances of thehoneybeeApis mellifera. Pesticide Biochemistry andPhysiology 78:83-92.

Desneaux, N., A. Decourtye, and J. Delpuech. 2007.Te sublethal effects of pesticides on beneficial arthro-pods. Annual Review of Entomology 52:81-106.

Evans, E., R. Torp, S. Jepsen, and S. Black. 2008.Status Review of Tree Formerly Common BumbleBee Species. 63 pp. Portland: Te Xerces Society forInvertebrate Conservation. www.xerces.org/wp-content/

uploads/2009/03/xerces_2008_bombus_status_review.pdfFrankie, G. W., R. W. Torp, M. H. Schindler, B.Ertter, and M. Przybylski. 2002. Bees in Berkeley?Fremontia 30(3-4):50-58.

Greenleaf, S. S., N. M. Williams, R. Winfree, and C.Kremen. 2007. Bee foraging ranges and their relation-ship to body size. Oecologia 153:589-596

Hartley, M. K., W. E. Rogers, E. Siemann, and J. Grace.2007. Responses of prairie arthropod communities to fireand fertilizer: balancing plant and arthropod conserva-

tion. American Midland Naturalist 157:92-105.Javorek, S. K., K. E. Mackenzie, and S. P. VanderKloet. 2002. Comparative pollination effectivenessamong bees (Hymenoptera: Apoidea) on lowbush blue-berry (Ericaceae: Vaccinium angustifolium). Annals ofthe Entomological Society of America 95:345-351.

Johansen, C. A. 1977. Pesticides and pollinators.Annual Review of Entomology 22:177-192.

Johansen, E. W., and D. F. Mayer. 1990. PollinatorProtection: A Bee and Pesticide Handbook. Cheshire,C: Wicwas Press.

Kearns, C. A., and J. D. Tompson. 2001. Te NaturalHistory of Bumblebees. A Sourcebook for Investiga-tions. Boulder: University Press of Colorado. 130pp.

Kearns, C. A., D. A. Inouye, and N. M. Waser. 1998.Endangered mutualisms: the conservation of plant-pollinator interactions. Annual Review of Ecology &Systematics. 29:83-113.

Kremen, C., N. M. Williams, and R. W. Torp.2002. Crop pollination from native bees at risk fromagricultural intensification. Proceedings of the NationalAcademy of Sciences 99:16812-16816.

Kremen, C., N. M. Williams, R. L. Bugg, J. P. Fay,

and R. W. Torp. 2004. Te area requirements of anecosystem service: crop pollination by native bee com-munities in California. Ecology Letters 7:1109-1119.

Losey, J. E., and M. Vaughan. 2006. Te economicvalue of ecological services provided by insects.Bioscience 56:311-323.

Mader, E., M. Spivak, and E. Evans. 2010. ManagingAlternative Pollinators: A Handbook for Beekeepers,Growers, and Conservationists. 167 pp. Beltsville:Sustainable Agriculture Network.

McFrederick, Q. S., and G. LeBuhn. 2006. Are urbanparks refuges for bumble bees Bombusspp. (Hymenop-tera: Apidae)? Biological Conservation 129:372-382.

Michener, C. D. 2000. Te Bees of the World. 913 pp.Baltimore: John Hopkins University Press.

Morandin, L., and M. Winston. 2006. Pollinatorsprovide economic incentive to preserve natural landin agroecosystems. Agriculture, Ecosystems andEnvironment 116:289-292.

National Research Council (NRC) Committee on Sta-tus of Pollinators in North America. 2007. Status ofPollinators in North America. Washington, DC: TeNational Academies Press.

Ooole, C., and A. Raw. 1999. Bees of the World, 192pp. London: Blandford.

Ozkan, H. E. 2000. Reducing Spray Drift. Ohio StateUniversity Extension Bulletin. 816-00. Columbus, OH.

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Potts, S. G., B. Vulliamy, S. Roberts, C. Ooole, A.Dafni, G. Neeman, and P. G. Willmer. 2005. Roleof nesting resources in organizing diverse bee com-munities in a Mediterranean landscape. EcologicalEntomology 30:78-85.

Shepherd, M. D., S. L. Buchmann, M. Vaughan, andS. H. Black. 2003. Pollinator Conservation Handbook:A Guide to Understanding, Protecting, and Providing

Habitat for Native Pollinator Insects. 145 pp. Portland:Te Xerces Society for Invertebrate Conservation.

Shuler, R. E., . H. Roulston, and G. E. Farris. 2005.Farming practices influence wild pollinator populationson squash and pumpkin. Journal of EconomicEntomology 98:790-795.

Smallidge, P. J., and D. J. Leopold. 1997. Vegetationmanagement for the maintenance and conservationof butterfly habitats in temperate human-dominatedhabitats. Landscape and Urban Planning 38:259-280.

epedino, V. J. 1981. Te pollination effi ciency of thesquash bee (Peponapis pruinosa) and the honey bee (Apismellifera) on summer squash (Cucurbita pepo). Journal ofthe Kansas Entomological Society 54:359-377.

Tompson, H. M. 2003. Behavioural effects of pesticidesuse in bees their potential for use in risk assessment.Ecotoxicology 12:317-330.

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on agricultural intensification and biodiversity ecosys-tem service management. Ecology Letters 8:857-874.

Vaughan, M. and M. Skinner. 2009. Using Farm Bill Pro-grams for Pollinator Conservation. United States Depart-ment of Agriculture NRCS. echnical Note No. 78.

Vaughan, M., and S. H. Black. 2006. Enhancing NestSites for Native Bee Crop Pollinators. Agroforestry

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Applications 17:910-921.Winfree, R., N. M. Williams, H. Gaines, J. S. Ascher,and C. Kremen. 2008. Wild bee pollinators provide themajority of crop visitation across land-use gradients inNew Jersey and Pennsylvania, USA. Journal of AppliedEcology 45:793-802.

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Notes


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Notes


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Alternative Pollinators: Native Bees

By Eric Mader, Mace Vaughan, Matthew Shepherd

and Scott Hoffman Black

The Xerces Society for Invertebrate Conservationwww.xerces.org. Published 2010

Holly Michels, EditorAmy Smith, Production

This publication is available on the Web at:

www.attra.ncat.org/attra-pub/nativebee.html

orwww.attra.ncat.org/attra-pub/PDF/nativebee.pdf

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40731158 alternative pollinators native bees

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