order coleoptera beetles. beetle collections beatle collections
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Coleoptera - Beetles
Largest of the insect orders40% of known species occur in
coleopteraAbout 30,000 species US and CanadaSizes from < 1mm to 125 mm (about 5”)
Coleoptera - Beetles
Many serious economic pestsHabitats vary greatly Beetles are found in most all situationsSubterranean, aquatic or semi-aquatic
Beetle Basics
Beetles have chewing mouthparts for chewing wood or crushing seeds
Beneficial varieties attack insect pests and others act as scavengers
Scobicia declivis the lead-cable borer is capable of boring through the lead sheathing of telephone cable
Beetle Basics
Most beetles have 2 pairs of wingsThe front wings or Elytra are leathery or
hard and brittleThe hind wings are membranous and are
folded under the elytraThe hind wings are the wings used for
flight
Feed the Beetle
Feed different plant and animal materialsPlant eaters, predators, scavengers, eat
fungi or molds; very few are parasitesPlant eaters – feed on foliage, fruits, nuts,
flower, wood borers, some attack roots
Feed the Beetle
Others eat stored plant and animal products, clothing, leather, various fabrics, and various other organic materials
Feed the Beetle
Beetles undergo a complete metamorphosis
There are several variations in the larval form
Life cycles vary from 4 generations per year to one generation in several years
Feed the Beetle
Most species – one generation per yearThey may overwinter in any life stageLarvae have 6 legs
Scarab Beetles
Family ScarabaeidaeAbout 1,400 species in
North AmericaVary greatly in shape,
size and colorSome incredible metallic
shadesHeavy-bodied Oval to elliptical in
shape - convex
Plusiotis chrysargyreae
Scarab BeetlesVaried habitsFeed on dung,
carrion, decomposing plant materials
Live in nests or burrows of vertebrates, or ant or termite colonies
Giant Dung Beetle
Dung Beetle Crossing
Scarab Beetles
Feed on live plant materials – fruit, flowers, foliage, grasses
Serious pests to turf, golf greens, ag. crops
Larvae are ‘C’-shapedLarval form is damaging
life stage
‘C’-Shaped Larvae
Bark Beetles
Family ScolytidaeThe three most
important genera include: Dendroctonus, Ips and Scolytus
Bark beetles – small, cylindrical beetles <8mm
Usually brownish or black Itty-Bitty Beetles
Bark Beetles
Bark beetles can be divided into two groups
Bark beetles – feeds on inner bark and succulent wood
Ambrosia beetles – feeds ambrosia – fungus they cultivate
Ambrosia Fungus
Bark Beetles
Lives within the bark, feeds at the surface of the wood on the phloem tissue
“Engravers” – Ips and Scolytus spp. which cut deeply into the sapwood
Scolytidae Galleriesw/ an “Engraver’s” path in
the center
Bark Beetles
Bark beetles feed on dying trees
Some species infest and kill living trees, particularly conifers
These trees are typically under physical stress Trees Killed By Bark
Beetles
Bark Beetles
Three species of scolytid beetles merit the most economic importance:
DendroctonusIpsScolytus
Bark Beetles
Fungus is “blue-stain” or “brown-stain”
Adults introduce fungi, larvae spread it
Fungus clogs the water transport vessels
Sap or pitch production is suppressed
Blue-Stain Fungus
Bark Beetles
Bark beetles can overwhelm a tree’s natural defenses by their sheer numbers
Adults respond to a combination of odors emitted from the resin from the potential host tree and chemical signals (pheromones) from the first colonies
The result – thousands of beetles may infest a tree simultaneously
Bark Beetles
Species of bark beetles can either be monogamous or polygamous
In monogamous species the female bores the initial hole in the tree
The male clears the frass behind herThe female lays her eggs in notches
along the sides of the gallery
Bark Beetles
The eggs hatch into ‘C’-shaped larvaeThe larvae begin boring at right angles to
the gallery As the distance increases from the main
gallery the “larval mines” become larger and begin to fan out
The larvae pupate at the ends of the mines
Bark Beetles
The new adult beetles emerge through round holes bored through the bark
After the brood emerges the tree appears to have been peppered with “shot” holes
“Shot” Holes in Bark
Bark Beetle Impact
Bark beetles have a greater impact on North American forests than any other insect
Singularly responsible for the death of more than 4 billion board-feet of timber annually
Over 90% of the insect caused mortality
Bark Beetle Impact
5 species of bark beetle responsible for most of the damage
Southern Pine Beetle (Dendroctonus frontalis)
Douglass Fir Beetle (D. pseudotsugae)Mountain Pine Beetle (D. ponderosae)Western Pine Beetle (D. brevicomis)Spruce Beetle (D. obesus)
The Evidence
Recognized by fading foliage colorNoticeable in groups or stands of treesFrass or hardened pitch-tubes on the
barkLarge amounts of woodpecker activityBark beetles are host specificGalleries are characteristic to each
species
Dutch Elm Disease
Spread by the European Elm Bark Beetle (Scolytus multistriatus)
Probably introduced into Europe from Asia around WWI
Thought to have entered the United States in the 1920s
It was first reported in Ohio in the 1930sIt has since spread across most of North
AmericaThe American elm has been almost completely
eliminated from the urban landscape
Ambrosia Beetles
Feed in live or freshly killed treesThe fungus they cultivate stains and
reduces the value of woodLarvae and adults share galleriesAdults care for larvae and feed them on
the ambrosia fungusAdults move to new trees carrying
conidia of fungus to infest new trees