Entomology Crash Course for Master Gardeners

Dr. Ayanava MajumdarExtension Entomologist

Alabama Cooperative Extension SystemGulf Coast Research & Extension Center

8300 State Hwy 104, Fairhope, Alabama 36532Cell phone: 251-331-8416

Entomology Crash Course for

Master Gardeners

Objectives & course lay-out:

• Techniques for basic insect identification

• Practical ways of scouting

• Use of monitoring devices

• Use of trap crops for sustainable veg. prod.

• Discussion on new invasive insects

All presentations will be available on CD or website.

…with emphasis on vegetable production

IMPORTANT INSECT PEST ORDERS

Dr. Ayanava Majumdar

Extension Entomologist

Alabama Cooperative Extension System

Gulf Coast Research & Extension Center

8300 State Hwy 104, Fairhope, Alabama 36532

Cell phone: 251-331-8416

PART 1

Fun Facts• Insects have been around for at least 350 million

years

• Over 900,000 described species

– U.S. has about 91,000 described species

– Less than 1% of these are considered pests

• Four largest insect orders: beetles (Coleoptera), flies (Diptera), ants (Hymenoptera), moths (Lepidoptera)

• In the typical backyard there are >1000 insects at any given time

– have exoskeletons, segmented bodies and jointed appendages

– exoskeleton must be shed periodically

• Insects:

– Three body regions (head, thorax and abdomen)

– Six legs

• Arachnids (spiders, mites, ticks):

– Two body regions (head and abdomen)

– Adults have eight legs

Insects and Their Relatives (Arthropods)

• Insects need to shed (molt) their skin (exoskeleton) and produce a new larger one in order to grow.

• The period between molts is called an instar.

• Most insect life cycle consist of between 4 and 8 instars before they become an adult and stop growing.

Insect Growth

• Insects can drastically change in shape and form during their growth and development. This is called metamorphosis (change in form).

• There are two forms of metamorphosis, complete and incomplete.

• The stage of development of an insect will affect way you attempt to manage that insect.

Insect Growth

Complete Metamorphosis

•Four distinct growing stages:

–Egg- immobile–Larvae- feeding–Pupa- immobile–Adult- reproduction

• Butterflies, moths, flies, beetles, wasps, and bees.

Incomplete Metamorphosis

• Young resemble adults but without wings

• No Pupal stage• Egg→nymph→ adult• True Bugs, dragonflies, grasshoppers, termites

Coleoptera (beetles,weevils)

Mexican bean beetle

Some insect have defense markings

(click beetle)

Wireworms

Vegetable weevil

Facts about beetles (Coleoptera)

• Characteristics: forewings are hard, hindwings are membranous, long-lived in soil, poor fliers

• Have four life stages – egg, larva (grub), pupa, adult

• Grubs have strong mouthparts & are root feeders

• Beetles (adult) are foliage/flower feeders and may transmit diseases

• Often overwinter in adult or larval stage which are tough-skinned

Diptera (flies)

Vegetable leafminerSeedcorn maggots

Mouth hooks of maggots

Facts about flies (Diptera)• Characteristics: very good flier

(one pair of wings), hairy body of adult, larva (maggots) hairless & reduced head, antennae small

• Have four life stages – egg, larva (maggot), pupa, adult

• Larva have mouth hooks to scrape root surface

• Adult flies feed on nectar or solids (sponging mouth type)

• Often overwinter in larval stage – tough-skinned maggots

Hemiptera (true bugs)

Piercing-sucking mouthparts (beak)

Stink bug

Leaf-footed bug

Aphids

Facts about true bugs (Hemiptera)

• Characteristics: triangular area on top, wings are partially hardened, antennae short

• Some are beneficial species (assassin bugs, big-eyed bugs)

• Have three life stages – egg, larva (nymph), adult

• Often overwinter in adult stage – immatures are vulnerable to predation.

• Piercing-sucking mouthparts

Lepidoptera (moths, butterflies)F

all

arm

yw

orm

Granulate cutworm

Tomato hornworm

Imported cabbageworm

Identifying larvae by structure

Thoracic legs Abdominal prolegs Anal proleg

Normal number of prolegs = 4 (cutworms, armyworms)

< Number of prolegs = 3 (green cloverworm)

Number of prolegs = 2 (cabbage looper) >>

• Complete lifecycle – egg, larva (caterpillar), pupa, adult

• Some of the adult moths are fastest fliers in insect kingdom.

• Larvae are damaging stage, adult has siphoning mouthparts for sucking nectar

• Some members have become insecticide tolerant (diamondback moth, corn earworm)

• Try controlling these pests in early stages (small larva)

Facts about moths & butterflies

Head of butterfly showing siphoning mouthparts (coiled

beak)

Orthoptera (grasshoppers)

All you wanted to know about grasshoppers:http://www.sidney.ars.usda.gov/grasshopper/index.htm

• Short-horned grasshopper (Acrididae)• Crickets (Gryllidae)• Mole crickets (Gryllotalpidae)

• Life stages: egg, nymph, adult

• Damage is caused by overlapping generations (nymphs + adults)

• Damage intense in dry years

• Eggs laid in clusters in soil with sharp ovipositor, food for many natural enemies

• Extremely mobile and have unique behavior patterns (e.g., infections)

Facts about grasshoppers

Thysanoptera (thrips)

Flower thrips

Actual size = 5 mm

Tobacco thrips

• Actual size = 5 mm, commonly seen on flowers

• Life stages: egg, larva, prepupa, pupa, adult

• Damage is caused by the rasping mouthparts

• Damage intense in dry years

• Extremely mobile, moved by storms

• Transmit diseases between plants

Facts about thrips

Key insect orders

• Coleoptera

• Diptera

• Hemiptera

• Lepidoptera

• Orthoptera

• Thysanoptera

Questions?