Entomologyfor Master Gardeners

David J. Shetlar, Ph.D.The “BugDoc”

The Ohio State University, OARDC & OSU Extension

Columbus, OH

© January, 2009, D.J. Shetlar, all rights reserved

What is Entomology?

The study of insects (and their near relatives).

What are insects (and near relatives)?

Insects and their relatives areARTHROPODS.

Review of Zoological Nomenclature(classifying & naming)

Taxonomic Categories

PhylumClass

OrderFamily

GenusGenus & species

Review of Zoological Nomenclature

Taxonomic Categories

Kingdom - AnimalaePhylum - Arthropoda

Class - Hexapoda (=Insecta)Order - Coleoptera

Family - ScarabaeidaeGenus - Popillia

Genus & species -Popillia japonica Newman

What are some other Animal Phyla?

• Protozoa - single-celled animals.

• Platyhelminthes - flatworms, tapeworms

• Nematoda - roundworms

• Mollusca - clams, snails & slugs, squids

• Echinodermata - starfish, sea urchins

• Annelida - segmented worms (earthworms)

• Chordata - fish, amphibians, reptiles, birds, mammals

Phylum Nematoda – Roundworms

(>15,000 species, all trophic areas)

Phylum Annelida – Segmented Worms(9,000 species, all trophic areas)

Phylum Mollusca – Snails/Slugs, Clams, Cephalopods

(50,000 species, aquatic and terrestrial)

Phylum Chordata – Urocordata, Cephalocordata, Vertebrata

(70,000 species)

Characteristics of the PhylumArthropoda

• The segmented bodies are arranged into regions: e.g., head, thorax, abdomen in insects; cephalothorax and abdomen in arachnids and some crustaceans; head and trunk in millipedes and centipedes.

• The have paired appendages.

• They posses a chitinous exoskeletion that must be shed during growth.

• They have bilateral symmetry.

• The nervous system is ventral (belly) and the circulatory system is open and dorsal (back).

Arthropod Groups (taxa)

The arthropods are divided into two large groups that exist today:

The Chelicerates

and

The Mandibulates

Chelicerate Arthropod Characters:

• Pincher-like mouthparts - chelicerae - and pedipalps

• NO antennae

• Two body regions, usually - cephalothorax & abdomen

• Four pairs of legs

• Horseshoe crabs and arachnids are only living groups

Mandibulate Arthropod Characters:

• Mouthparts are mandibles - normally chewing sideways

• One or two pairs of antennae

• Various body region arrangements - cephalothorax & abdomen / head & trunk / head, thorax & abdomen

• Variable leg numbers

• Insects, crustaceans & myriapods

Classes of Arthropods:

Chelicerates –Class Xiphosura – horseshoe crabs

Class Arachnica – arachnids

Mandibulates –Class Crustacea – crustaceans

Class Diplopoda – millipedes

Class Chilopoda – centipedes

Class Symphyla – garden centipedes

Class Hexapoda – insects

Orders of Arachnids

• Scorpiones - scorpions

• Pseudoscorpiones - false scorpions

• Opiliones - daddy-long-legs or harvestmen

• Acari - mites & ticks

• Araneae - spiders

Scorpion Tick(a mite)

Pseudoscorpion

Daddy-long-legs

WolfSpider

Pseudoscorpion

pedipalps &chelicerae

cephalothorax

abdomen

Mite and Tick Body Regions

American dog tick male

Blacklegged (deer) tick female

American dog tick female laying egg mass (1000-2000 eggs!).

Clover mites

Twospotted spider mites

Predatory mite

Opiliones (=daddy-long-legs, harvestmen)

cephalothorax abdomen

pedipalp

chelicera (fang)

cephalothorax

abdomen

narrow waist

Spider Anatomy

Abdomen

Pedipalp

Chelicera (fang)

Cephalothorax

Jumping Spider

Wolf spider with egg case Spitting spider

Tarantula Orbweaving spider

Black widow with egg case

Brown recluse (fiddleback)

Classes of Myriapods(many legged arthropods)

(all have one pair of antennae, a head region, and trunk with many pairs of legs, use trachea)

• Diplopoda - millipedes

• Chilopoda - centipedes

• Symphyla - garden centipedes

Myriapods

Millipede (Diplopoda)

Two pair of legs per visible segment, attached under body.

Centipede (Chilopoda)

Pair of fangs under head, one pair legs per visible segment - attached to side of body.

Symphylan (Symphyla)[garden centipede]

No fangs, no eyes, legs attached to side of body.

[one pair of antennae, head & trunk regions, trunk with many pairs of legs]

Millipede (Diplopoda)

Centipede (Chilopoda)

Garden centipede (Symphyla)

Classes of Crustacea(mostly marine, fresh water, a few terrestrial)

(all have two pair of antennae, five or more pairs of legs, segmented abdominal appendages, head & trunk or

cephalothorax & abdomen body arrangement, have gills)

• Isopoda - sowbugs or pillbugs

• Amphipoda - sand fleas, amphipods

• Cirripedia - barnicles

• Decapoda - crabs, lobster, shrimp

• several other minor orders

Crayfish External Morphology

Sowbugs (Isopoda), terrestrial crustaceans

Class Hexapoda(the insects)

• Three body regions – head, thorax, abdomen

• Thorax with three pairs of legs; normally two pairs of wings in adult stage

• Head with one pair of antennae

• Respiration by trachea

• Terrestrial & fresh water inhabitants

Lubber Grasshopper

antenna

compound eye

frons

clypeus

ocelli

labrum

mandible

maxilla

labium

Lubber Grasshopper Head

pronotum

coxa

trochanter

femur

tibia

tarsus

spiraclemesopleuron

metapleuron

Lubber Grasshopper Thorax

abdominal tergites

abdominal sternites

cercus

spiracles

Lubber Grasshopper Abdomen

Insect Respiratory System

Cana lily skipper (a butterfly) larvae have an almost completely transparent exoskeleton, thereby allowing a good

view of the tracheal system.

Incomplete Metamorphosis Example(hairy chinch bug)

egg 1st 2nd 3rd 4th 5th normal wing short wing instar instar instar instar instar adult adult

Egg Nymphal AdultStage Stage Stage

Complete Metamorphosis Example(northern masked chafer)

egg 1st 2nd 3rd pupa adult instar instar instar

Egg Larval Pupal AdultStage Stage Stage Stage

Hexapod OrdersEntognathous Hexapods –

Order Protura

Order Collembola

Order Diplura

Ectognathous apterygote Hexapods –

Order Microcoryphia

Order Thysanura

Pterygote Hexapods –

(simple metamorphosis)

Order Ephemeroptera

Order Odonata

Order Orthoptera

Order Phasmatodea

Order Dermaptera

Order Plecoptera

Order Isoptera

(simple metamorphosis cont’d)

Order Mantodea

Order Blattodea

Order Hemiptera

Order Thysanoptera

Order Psocoptera

Order Phthiraptera

(complete metamorphosis)

Order Coleoptera

Order Neuroptera

Order Hymenoptera

Order Trichoptera

Order Lepidoptera

Order Siphonaptera

Order Diptera

Orders of Insects(no metamorphosis)

• Some consider these groups insect-like and place in different class or subclass.

• Adults do not have wings and may molt after becoming mature

• Collembola - springtails

• Thysanura - silverfish, firebrats

Order Collembola (glue wedge)

springtails

• Wingless (primitively)

• Chewing mouthparts

• Gradual (no) metamorphosis

• Adults continue to molt

• Feed on plants, bacteria, & fungi

• Important as decomposers

collophore furcula

Order Thysanura (bristle tail) silverfish & firebrats

• Look like they have 3 tails –• 2 cerci• 1 median filament

• Wingless (primitively)• Most are covered with scales • Chewing mouthparts• Gradual (no) metamorphosis• Feed on organic matter, starchy

materials

silverfish

firebrat

Order Orthoptera (straight wing) grasshoppers & crickets

• Two pairs wings• Forewings leathery & narrow; protect• Hindwings membranous, fan-folded• Some are wingless (cave crickets)

• Most have hind legs enlarged for jumping

• Females have prominent ovipositor • Produce songs by rubbing wing bases

together or rubbing the wings on their legs

Mating pair of grasshoppers

Female cone-nose grasshopper

Order Dermaptera (skin wing) earwigs

• Cerci like forceps, pinchers• Defense, prey capture, mating

• Elongate, flattened

• Two pairs of wings • Forewings usually short, hard

• Hindwings membranous, folded

• Few species are wingless

Seashore earwig

Ringlegged earwig

Order Isoptera (equal wing)

termites

• Social• Reproductives (queens & kings)

• Four wings of equal size• Wings twice the length of the body• Wings lack cross-veins

• Workers & soldiers• Lack wings• Body white• Distinguish from ants:

• Lack of elbowed antennae• No constriction between abdomen & thorax

Swarming reproductive termites

Workers and a soldier

Order Mantodea (soothsayer)

mantids / praying mantid

• Large (50-100 mm)

• Forelegs modified for grasping prey

• Predatory

• Chewing mouthparts

• Gradual metamorphosis

Order Blattodea cockroaches

• Flattened body• Long slender antennae• Wings thickened, leathery• Wings reduced in some species• Legs modified for running• Chewing mouthparts• Gradual metamorphosis• Feed on organic matter, stored

products, plants

Order Hemiptera (half wing)true bugs & bug-like insects

• Formerly 2 separate orders; recently combined

• Suborder Heteroptera

• Suborders Auchenorrhyncha & Sternorrhyncha (former Homoptera)

Order Thysanoptera (fringe wing)

thrips

• Small (most <4 mm), elongate• Chewing mouthparts

• Small conical beak• Rasping mouthparts

• Most with 4 wings • Strap-like• Fringed with long bristles• Some species are wingless

Order Phthiraptera(lice without wings)

• Formerly 2 separate orders

• Suborder Mallophaga (wool eater): chewing lice

• Suborder Anoplura (unarmed tail): sucking lice

Head louse

Head louse nit (egg)

Order Coleoptera (sheath wing) beetles

• Largest order in animal kingdom• Chewing mouthparts• Complex metamorphosis• Forewings (elytra) are hardened, opaque,

meet in the midline of back• Hindwings membranous, folded under elytra• Feed on plants, organic matter, stored

products; or predatory

Order Neuroptera (nerve wing)lacewings & dobsonflies, antlions, owlflies

• Wings• Membranous, 2 pairs • Approximately equal size• Many veins & cross-veins

• Chewing mouthparts, sometimes modified

• Complex metamorphosis• Members of interest are predators

Order Hymenoptera(marriage wing)

bees, wasps, sawflies, ants

• Wings:• 4 membranous wings• Hind pair smaller than front pair • Pairs attached by row of small hooks

• Bees, wasps, & ants have second abdominal segment constricted & narrow; i.e. effect of “wasp-waist”

• Sawflies have broadly joined thorax & abdomen

Order Lepidoptera (scale wing)moths & butterflies

• Shingle-like scales on wings • 4 wings, often colorful • Complex metamorphosis• Mouthparts

• Chewing in larva• Sucking (siphoning) or none in adults• Proboscis in butterflies: coiled siphon

• Larvae (caterpillars) – 2-5 prolegs on abdomen

Order Siphonaptera(sucking wingless) fleas

• Body: small, hard, laterally compressed

• Wingless

• Mouthparts:• Piercing/sucking for blood in adult

• Chewing in larva

• Larvae feed on organic matter

Order Diptera (two wing)true flies

• Mouthparts:• Sucking: modified piercing/ sucking,

sponging, lapping, slashing in adult• Modified chewing in larva

• One pair wings, on mesothorax• Metathorax has 1 pair of small, knobbed

appendages (halteres)• Occasionally wingless