Insects (Chapter 7) or

What’s this Bug?

Did you know that . . .?

• The vast majority of

insects are either

beneficial or harmless

• Less than 3% of all insects

are classified as pests

• One-sixth of the world’s

food crops are consumed

by insect pests

spiders, ticks, and

centipedes (chilopods)

millipedes (diplopods)

snails (molluscs)

mites (arachnids)

spiders (arachnids)

pillbugs (crustaceans)

Not all “bugs” are

insects.

Arachnids

• Spiders and their Kin

Spiders

Ticks

Scorpions

Mites

• Spiders are mostly beneficial

two main body regions - cephalothorax

(head and thorax fused together)

abdomen

Arachnids: spiders, ticks, scorpions, mites

no antennae

simple eyes

four pairs of jointed legs

no wings

Mites

• Very small

• Piercing-sucking mouthparts – produce leaf stippling

• Web-spinning mites are common pests

– Like hot & dusty

– Outbreaks after insecticide application

– Find in greenhouses

• Rust, Bud & Blister mites have 4 legs

Isopods

• Sowbugs & Pillbugs

– Related to crayfish & breathe through gills

– Have 7 sets of legs

– Feed on decaying organic material & fruits laying directly on ground

– Strawberries, squash, etc

Wings - None, One or Two Pairs

Three Distinct Body Regions: Head, Thorax, Abdomen

Jointed Legs - Three Pairs Antennae - One Pair

Undergoes Metamorphosis

Insect Characteristics

Orthoptera - crickets, grasshoppers

Hemiptera, suborder Heteroptera - true bugs

Hemiptera, subover Homoptera - aphids, scale, hoppers

Lepidoptera - butterflies, moths

Coleoptera - beetles, weevils

Diptera - flies, mosquitoes

Hymenoptera - bees, ants

Common Insect Orders

Characterized by:

Mouthparts

Type of legs, wings, antenna

Metamorphosis

chewing mouthparts

piercing-sucking mouthparts

siphoning

Sponging

Gradual metamorphosis

The immature stages of these

insects are known as nymphs

• Except for size and the lack

of fully formed wings, the

nymphs and adults look very

much alike

• Molt outer shell to grow

bigger

Examples: grasshoppers, crickets,

termites, and true bugs

Insect has four distinct stages

Complete metamorphosis

Examples: bees, ants, wasps,

flies, beetles, butterflies, moths

and mosquitoes

egg

larvae - feeding, destructive stage

pupa - an inactive stage

adult - reproductive stage

Nymphs resemble adults, except for

being wingless. Both adults &

nymphs cause damage.

Moderate to large, hard-bodied

adults with two pairs of wings.

Front wings are hard, leathery

ORTHOPTERA - grasshoppers, locusts, crickets, mantids, cockroaches

Gradual metamorphosis, chewing mouth

parts

HEMIPTERA, sub order Heteroptera - true bugs

Gradual metamorphosis, Piercing-sucking

mouthparts in nymphs (immatures) and

adults

Recognized by

triangle on back

Harlequin Bug

Suborder HOMOPTERA -aphids, scales, leafhoppers, cicadas, whiteflies,

mealybugs

Gradual metamorphosis, piercing-

sucking mouthparts in nymphs

(immatures) and adults

Small, soft-bodied insects,

except for cicadas

Aphids

Mealybugs are considered a type

of scale. They are oval,

segmented, and covered with wax.

Scales may be small, round or football-

shaped, and armored (California red scale)

or soft-bodied (cottony cushion scale).

Hemiptera, Suborder:

HOMOPTERA

Whitefles are tiny sap-suckers found in

vegetables, ornamentals, and citrus trees.

Suborder HOMOPTERA -aphids, scales, leafhoppers,

cicadas, whiteflies, mealybugs

Leafhoppers feed on undersides of

leaves, transmit virus diseases. Hosts

are: beans, cucurbits, potatoes,

eggplants, grapes, and apples

Dermaptera - Earwigs

• Gradual metamorphosis

• Chewing mouthparts

• Forceps on rear end

• Can be pest or predator

LEPIDOPTERA - butterflies, moths

Larvae - chewing

Adults - siphoning

Complete metamorphosis

Mouthparts

Larvae are worm-like,

voracious feeders with prolegs

on abdomen and thorax. Adults are soft-bodied with two

pairs of membranous wings

covered with small scales.

Leaf-eating caterpillars (tomato hornworm, armyworms,

loopers) chew irregular holes. Many small caterpillars

roll leaves to form shelters.

LEPIDOPTERA - butterflies, moths

Moth vs. Butterfly

Moth

• Antennae are feathery or wiry

• Wings at rest – out-stretched, folded or angled

• Day & night

Butterfly

• Antennae end in a club

• Wings at rest out-stretched or held vertically

• Day-time only

Beetles = Coleoptera

• More Beetle species than all other animals

• Hard “shelled” forewing

• Vegetarians, predators, scavengers & parasites

COLEOPTERA - beetles, weevils

Complete metamorphosis

Chewing Mouthparts

(adults and larva)

Larvae (grubs, wireworms,

borers) have head capsule

COLEOPTERA - beetles, weevils

Adults have two pairs of wings.

Horny, leathery front wings (elytra)

cover membranous hind wings

underneath, used for flying.

COLEOPTERA - beetles, weevils

Flea beetles, wireworms (click beetle larvae), cucumber

beetles, vegetable weevils, and green fruit beetles are

common pests in California home vegetable gardens

Lady beetles (ladybugs) are beneficials

Flies & Mosquitoes - Diptera

Only 2 wings (1 pair)

Mouth parts adapted for sucking

or piercing & sucking

Complete metamorphosis

Important garden and agricultural pests include the

cabbage maggot, onion maggot, apple maggot, walnut

husk fly, fruit flies, and leafminers

DIPTERA - flies, mosquitoes, gnats, midges

cabbage maggot

onion maggot apple maggot

walnut husk fly

Hymenoptera: Ants, Wasps, Bees, Sawflies

• Narrow waists

• Chewing mouthparts

• Complete metamorphosis

• Can have up to 2 pairs of membranous wings

HYMENOPTERA - bees, wasps, ants, sawflies

Many species are beneficial,

are parasites, natural

enemies or biological control

agents of many pest insects

Raspberry horntail

Pear sawfly larvae Leafcutter wasp

Rose sawfly damage

HYMENOPTERA - bees, wasps, ants, sawflies

WHAT IF YOU DON’T SEE A BUG?

Symptoms of insect attack: Chewed foliage or fruit

Grape leafhopper

Symptoms of insect attack: bleached, stippled or mined leaves

Symptoms of insect attack: distortion

(swelling, twisting, cupping) of plant parts

Symptoms or signs of insect attack: Dieback of twigs, stems or plant

Peach tree borer

Symptoms of insect attack: presence of insect-related debris

sooty mold

frass

So What’s that Bug?

Red-humped caterpillar

Bark Beetle

Spider mites – not visible to

the naked eye, look for

webbing, suck juices from

plants

Stink bugs attack stone fruits, broccoli,

cabbage, tomatoes. They give off an

offensive odor when disturbed.

Centipede: not an insect,

but a general predator of

insects

Curled, distorted leaves

and sticky honeydew

exudates on leaves are

strong signs of aphid

infestation.

Tomato Hornworm: voracious

muncher of leaves

Lygus bugs

attack beans,

strawberries and

orchard crops.

Assassin Bug: eats beetles,

caterpillars, hornworms & other

insects

Syrphid fly larvae are

important predators of

aphids & scales

Adults are

valuable

pollinators

Look like a bee,

but quicker and

don’t buzz

Earwig, chews flowers & fruit,

can also be beneficial predator

by eating insects & larvae

Walnut Husk Fly: 2 wings,

compound eyes

Codling Moth: larvae are

“worm” in the center of

apples & pears, look for

stings, remove overwintering

pupae

Lacewing: good bug, preys on

aphids and whiteflies

Cucumber beetle: bad

bug, eats crops &

foliage

Scales: suck plant juices

under their covering