Entomology 101 Orders of Insects

1. Entomology 101 Orders of Insects David J. Shetlar, Ph.D. The “BugDoc” The Ohio State University, OARDC & OSU Extension Columbus, OH © Sept, 2009, D.J. Shetlar, all rights reserved

2. Class Hexapoda (the insects) • Three tagmata – 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

3. Class Hexapoda (all have one pair of antennae, a head, thorax & abdominal regions, three pair of legs, adults usually have wings, use trachea) Life Cycle Groups • Simple Metamorphosis (=incomplete) - egg, nymph, adult stages • Complete Metamorphosis - egg, larva, pupa, adult stages

4. Egg Nymphal Adult Stage Stage Stage Incomplete Metamorphosis Example (hairy chinch bug) egg 1st 2nd 3rd 4th 5th adult instar instar instar instar instar

5. 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 Adult Stage Stage Stage

6. Egg Larval Pupal Adult Stage Stage Stage Stage Complete Metamorphosis Example (May/June beetle) egg 1st 2nd 3rd pupa adult instar instar instar

7. Egg Larval Pupal Adult Stage Stage Stage Stage Complete Metamorphosis Example (northern masked chafer) egg 1st 2nd 3rd pupa adult instar instar instar

8. Hexapod Orders Entognathous 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

9. 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 • Thysanura - silverfish, firebrats • Collembola - springtails

10. Order Thysanura (=bristle tail)silverfish & firebrats • Look like they have 3 tails – • 2 cerci • 1 median filament • Wingless (originally) • Most are covered with scales • Chewing mouthparts • Gradual (no) metamorphosis • Feed on organic matter & starches

11. Thysanura (=bristletail) (silverfish, firebrats; 0.4K spp.) [no wings as adults, usually 3 caudal appendages (two cerci and median filament); adults may continue to molt] Silverfish Fourlined silverfish

12. Order Collembola (=glue wedge)springtails • Wingless (primitively) • Chewing mouthparts • Gradual (no) metamorphosis • Adults continue to molt • Feed on plants, bacteria, & fungi • Important as decomposers and bioindicators

13. Order Collembola (=glue wedge)springtails • Tiny, most < 3 mm • Collophore • Water regulatory structure • Underside 1st abdominal segment • Furcula • Forked jumping appendage • Underside 4th abdominal segment • Held bent under body • Escape by catapulting

14. Collembola (=glue wedge) (springtails; >6K spp.) [no wings as adults, caudal appendage designed for jumping (furcula & colliphore); adults may molt] Springtail with furcula exposed. Globular springtail, upper and lower views, spots on head are not eyes! Eyes are lower on head.

15. Aquatic springtails have waxy hairs that allow them to float on the water surface. These springtails feed on algae. Springtails often have long hairs and multicolored scales.

16. Orders of Insects (simple metamorphosis) • Ephemeroptera - mayflies, shadflies • Odonata - dragonflies, damselflies • Orthoptera - grasshoppers, crickets, katydids • Dermaptera – earwigs • Plecoptera - stoneflies • Isoptera - termites

17. Order Ephemeroptera (=short lived, on the wing)Mayflies • Nymphs (naiads) aquatic • Wings triangular, held over back • Front wings large, usually with many veins • Hind wings small or absent • Adults with 2 or 3 long caudal filaments • Last instar nymph flies from water (subimago) • Adults live for hours to a few days.

18. Ephemeroptera (=short lived on the wing) (Mayflies, shadflies, Canadian soldiers; 2K spp.) [front wings large, triangular, held over body at rest; hind wings small or absent; aquatic nymphs with abdominal gills; caudal appendages (2 or 3) long; chewing mouthparts often non-functional in adult] Mayfly adults, one two-tailed and one three-tailed. Mayfly naiad.

19. Hexagenia, large Mayfly, subimago (last instar nymph). Note cloudy wings and short tails. Hexagenia adult. Note clear wings and long tails.

20. Order Odonata (=toothed – large mandibles)Dragonflies and Damselflies • Front & Hind Wings narrow • Many veins and cross veins • Dragonflies hold wings out at rest • Damselflies hold wings over back • Nymphs (naiads) aquatic • Naiads predatory, have grasping mouthparts • Dragonfly naiads have rectal gills • Damselflies have leaflike gills on abdomen tip. • Adults are beneficial predators.

21. Odonata (=toothed) (dragonflies and damselflies; 5K spp.) [front and hind wings narrow with many cross veins, membranous; aquatic nymphs (naiads) predatory with caudal or rectal gills; antennae bristlelike, no abdominal cerci; chewing mouthparts]

23. Damselfly details

24. 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

25. Order Orthoptera (straight wing) grasshoppers & crickets • Chewing mouthparts • Gradual metamorphosis • Antennae short or long • Most feed on plants • Some feed on organic matter, stored products; few predatory

26. Orthoptera (=straight wing) (grasshoppers, crickets, Katydids; >20K spp.) [front wings leathery, hind wings folded like a fan, chewing mouthparts, two cerci - usually short]

27. Mating pair of grasshoppers

28. Female cone-nose grasshopper

29. Black field cricket

30. Order Dermaptera (=skin wing)earwigs • Chewing mouthparts • Gradual metamorphosis • Omnivorous • Mostly scavengers • Occasional pests of plants • Nuisance pest in homes

31. Order Dermaptera (=skin wing) earwigs • Cerci shaped like forceps, pinchers • Defense, prey capture, mating • Elongate, flattened • Two pairs of wings • Forewings usually short, hard • Hindwings membranous, folded • Few species are wingless

32. Dermaptera (=skin wing) (earwigs; 1.8K spp.) [front wings short, leathery; hind wings double folded; abdominal cerci forceps-like; chewing mouthparts] Seashore earwig adult European earwig with eggs

33. Order Plecoptera (=folded wing)Stoneflies • Nymphs Aquatic (naiads) • Abdominal &/or thoracic gills • Predators & herbivores • Flat with obvious cerci • Chewing Mouthparts • Adults with • Front wing narrow, bladelike • Hind wing broad, flolded • Medium to long cerci • Good indicators of water quality

34. Plecoptera (=folded wing) (stoneflies; 2K spp.) [front wings narrow; hind wings folded fanlike; aquatic nymphs (naiads) with abdominal gills; abdominal cerci straight, moderately long; chewing mouthparts]

35. Giant Stonefly Adult

36. 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

37. Order Isoptera (=equal wing)termites • Chewing mouthparts • Gradual metamorphosis • Feed on wood and plant materials • Protozoans digest cellulose • Significant structural pest • Build distinctive nests

38. Isoptera (equal wing) (termites; >2.3K spp.) [social insects, winged reproductives with both wings same size and membranous; straight or curved antennae consists of beadlike segments; abdomen broadly joined to thorax; one to two-segmented cerci; chewing mouthparts]

39. Subterranean termite queen, king, workers and soldier

40. Nasutiform termite nest in tree. Nasutiform soldiers protecting opened nest.

41. Orders of Insects (incomplete metamorphosis cont’d) • Mantoidea – mantids • Blattodea – cockroaches • Hemiptera - true bugs & bug-like insects • Thysanoptera - thrips • Psocoptera - barklice, booklice • Phthiraptera - biting & sucking lice

42. Order Mantodea (=soothsayer)mantids / praying mantid • Large (50-100 mm) • Forelegs modified for grasping prey • Predatory • Chewing mouthparts • Gradual metamorphosis

43. Mantodea (=soothsayer) (mantids, praying mantis; ~1.8K spp.) [front legs raptorial (modified for grasping), prothroax elongated, chewing mouthparts, two short cerci]

44. Order Blattodea (=L. cockroach) 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

45. Blattodea (L. cockroach) (cockroaches; <4K spp.) [body flattened and oval, front wings leathery, hind wings folded like a fan, chewing mouthparts, two short cerci]

46. Order Hemiptera (=half wing)true bugs & bug-like insects • Formerly 2 separate orders; recently combined • Suborder Heteroptera • Suborders Auchenorrhyncha & Sternorrhyncha (former Homoptera)

47. Suborder Heteroptera the true bugs • Piercing/sucking mouthparts • Prominent beak arises from front of head • Two pairs of wings on most • Forewings: thickened front halves • Hindwings: membranous • Forewings lay flat, overlapping • Scutellum (▼-shaped)

48. Suborder Heteroptera true bugs • Many have scent glands • Plant feeders, predators, blood feeders • Gradual metamorphosis

49. Hemiptera (s.o. Heteroptera) (half wing) (true bugs; 23K spp.) [front wings half leathery & half membranous; hind wings membranous; usually long antennae; sucking mouthparts arise from front of head]