University of Michigan Biological Station

Biology 442 - Biology of Insects

Lecture Notes - Orders of Insects

1. Review of insect characters.
   1. 3 body segments.
   2. 3 pairs of legs.
   3. 2 pairs of wings.
2. Taxonomy and Classification.
   1. Hierarchy - Kingdom, Phylum, Class, Order, Family, Genus, Species.
   2. Endings - Class and Order, no standard; Superfamily, oidea; Family, -idae; Subfamily, -inae; Tribe, -ini; Genus and Species no standard but must agree.
   3. Pronunciation, Latinized but not consistent, best to listen and copy but good to try and be accurate because improves spelling. Two basic rules - all vowels are pronounced and penultimate syllable is accented. Book gives clues for most.
   4. Problems with common names. They do not always agree with scientific classifications, but they are useful. E. g. Alderfly, Sawfly, Junebug, Lightningbug, Barklouse.
3. Class Hexapoda.
   1. Several different ways of dividing the group.
      1. Entognatha, Insecta (Ectognatha)
      2. Apterygota, Pterygota
      3. Ametabola, Hemimetabola, Holometabola
   2. These subgroupings are variously divided. Will mention several of these as they arise.
4. Orders.
   1. Protura.
      1. Size - 0.5 to 1.5 mm.
      2. 19 spp. in N. A.
      3. Diagnostic characters.
         1. no eyes.
         2. no antennae.
      4. Habitats. moist soil, humus, mold, under bark, in decomposing logs.
      5. Food. decomposing organic matter, fungal spores.
      6. Other. 1st pair of legs function as antennae, can be very abundant in soil.
   2. Collembola (Springtails).
      1. Size - 0.25 to 6 mm.
      2. about 700 spp. in N. A.
      3. Diagnostic characters.
         1. small eyes.
         2. furcula (4th seg.), retinaculum.
         3. collophore (1st seg.).
      4. Habitats. Ubiquitous, common in soil, leaf litter, under bark, decaying logs, fungi, some on ponds, vegetation, in termite or ant nests, caves, snow.
      5. Food. Decaying plant material, fungi, bacteria, arthropod feces, pollen, algae.
      6. Other. May be up to 100,000/cubic meter of soil, not all have furcula or eyes.
   3. Diplura.
      1. Size - up to 7 mm.
      2. about 65 spp. in N. A.
      3. Diagnostic characters.
         1. no eyes.
         2. cerci and antennae.
      4. Habitats. In damp soil, under bark, stones, logs, in rotting wood, caves.
      5. Food. Decaying organic matter, fungi.
   4. Microcoryphia (Jumping bristletails).
      1. Size - up to 15 mm.
      2. 20 spp. in N. A.
      3. Diagnostic characters.
         1. Cylindrical body, arched thorax.
         2. Eyes large, contiguous
      4. Habitats. In grassy or wooded areas under stones, leaves, bark, on cliffs.
      5. Food. Algae, lichens, mosses, decaying fruit.
      6. Other. Similar to Thysanura, both have scales, long antennae, 3 caudal filaments. Eyes glow at night when illuminated. Jump when disturbed.
   5. Thysanura (Silverfish).
      1. Size - up to 19 mm.
      2. 18 spp. in N. A.
      3. Diagnostic characters.
         1. Flattened body.
         2. Eyes small, separate.
      4. Habitats. Inhabit buildings, ant nests, caves, under stones, in debris.
      5. Food. Feed on various starchy organic materials.
      6. Other. Can be pests in homes. Move very fast.
   6. Ephemeroptera (Mayflies). Start of Palaeoptera.
      1. Small to medium sized.
      2. about 600 spp. in N. A.
      3. Diagnostic characters.
         1. 2 or 3 long caudal filaments.
         2. Wings with many veins, forewings triangular, held over body at rest.
      4. Habitats. Nymphs aquatic in freshwater, some actively swim, others burrow in mud. Adults found near water.
      5. Food. Nymphs on algae and detritus. Adults do not feed.
      6. Other. Nymphs have gills on side of abdomen and 2 or 3 tails. These crawl out of water, molt to subimago (dull colored). Then molts to imago (shiny). Only insect with two fully winged stages. Lives only 1 or 2 days. Often have very large mass emergences with males mating in groups. They are important source of food for fish and are used as ecological indicators.
   7. Odonata (Dragonflies and damselflies).
      1. Size - 20 to 135 mm (up to 71 cm in fossils).
      2. about 400 spp. in N. A.
      3. Diagnostic characters.
         1. wings elongate, all 4 similar, rest with them stretched out flat (dragonflies) or above body (damselflies).
         2. compound eyes very large.
      4. Habitats. Nymphs aquatic in fresh water. Adults usually near water.
      5. Food. All stages predaceous on various small organisms. Dragonfly nymphs with specialized labium. Adults capture prey in flight with long legs.
      6. Other. Damselfly nymphs with 3 leaflike gills at end of abdomen, also used for swimming. Dragonfly nymphs have gills in rectum and use jet propulsion to move. Nymph crawls out onto vegetation and molts to adult. Adult color may take several days or weeks to develop. Live up to 8 weeks. Male copulatory organs on 2nd seg. Sperm is transfered from 9th seg., grasps female with claspers and she reaches up to get sperm. Oviposition often done while in tandem.
   8. Grylloblattaria (Rock crawlers). Start Neoptera and Orthopteroid orders.
      1. Size - 15 to 30 mm.
      2. 13 spp. in N. A.
      3. Diagnostic characters.
         1. wingless.
         2. pale colored.
         3. eyes small or absent.
         4. antennae and cerci long.
      4. Habitats. Arctic and alpine, talus slopes at edge of glaciers and ice caves.
      5. Food. Dead insects and other organic matter.
      6. Other. Mainly nocturnal. Females may have long ovipositor. Only recently recognized.
   9. Phasmida (Walking sticks).
      1. Size - 15 to 180 mm (up to 1 ft. in tropics).
      2. about 30 spp. in N. A.
      3. Diagnostic characters.
         1. Sticklike body, with or without wings.
         2. Legs not modified for jumping.
      4. Habitats. In trees or shrubs.
      5. Food. Herbivorous on trees and shrubs, can become pests.
      6. Other. Can regenerate legs, tarsi 5 segmented. Eggs scattered on ground. Often abundant in alternate years because of two year egg stage.
   10. Orthoptera (Grasshoppers, Crickets, Katydids).
       1. Size - variable small to large.
       2. about 1000 spp. in N. A.
       3. Diagnostic characters.
          1. Forewings many veined, leathery, hindwings membranous.
          2. Hindlegs modified for jumping.
          3. Antennae and cerci, long, well developed.
       4. Habitats. Occur most places.
       5. Food. Most are herbivorous, few predaceous, scavengers or omnivorous.
       6. Other. Some wingless. Females often have long ovipositor. Tarsi 3 or 4 segmented, chewing mouthparts. Many can produce and hear sounds.
   11. Mantodea (Mantids).
       1. Size - large, 50 to >100 mm.
       2. 20 spp in N. A.
       3. Diagnostic characters.
          1. Raptorial front legs.
          2. Long prothorax.
       4. Habitats. Often in grassy areas.
       5. Food. Predaceous on other arthropods. Sit and wait predators.
       6. Other. May eat mate. Egg case overwinters.
   12. Blattaria (Cockroaches).
       1. Size - medium to large, 6 - 50 mm.
       2. about 50 spp. in N. A.
       3. Diagnostic characters.
          1. Legs used for running, not jumping.
          2. Body flattened, pronotum concealing head.
          3. Cerci and antennae usually relatively long.
       4. Habitats. Often in houses, in leaf litter, under bark.
       5. Food. Omnivorous, feed on many things.
       6. Other. Pests in homes, not specific disease vectors, but cause mess and smell.
   13. Isoptera (Termites).
       1. Size - medium sized, 6 to >18 mm.
       2. about 40 spp. in N. A.
       3. Diagnostic characters.
          1. Antlike, without abdomen constriction.
          2. Wings, long similar in shape and size, held flat over abdomen at rest.
       4. Habitats. Primarily tropical, in temperate live in ground or wooden structures.
       5. Food. Cellulose, have bacteria or protists that digest food. Symbionts transfered by feeding on anal secretions and cast skins.
       6. Other. All are social with castes. Related to cockroaches. Only 1 sp. in southern Michigan.
   14. Dermaptera (Earwigs).
       1. Size - 4 to 30mm.
       2. 22 spp. in N. A.
       3. Diagnostic characters.
          1. pincherlike cerci.
          2. short, leathery forewings.
       4. Habitats. In cracks and crevices, under bark, often around dwellings.
       5. Food. Dead and decaying vegetable matter, some on living plants, predaceous.
       6. Other. Mainly nocturnal. Chewing mouthparts. Resemble rove beetles. Eggs laid in burrows, guarded by female.
   15. Embiidina (Web-spinners). Last Orthopteroid order.
       1. Size - about 10mm
       2. 10 spp. in N. A.
       3. Diagnostic characters.
          1. Elongate body.
          2. Legs short, stout. Basal segment of foretarsi enlarged to contain silk gland.
       4. Habitats. Mainly tropical. In silken galleries in leaf litter, under stones, in soil cracks, bark crevices, epiphytic plants.
       5. Food. Dead plant material.
       6. Other. Live in colonies of parent and brood. Females guard eggs and young. Winged or wingless. Body flattened in male, cylindrical in female.
   16. Plecoptera (Stoneflies).
       1. Size - small to medium.
       2. about 540 spp. in N. A.
       3. Diagnostic characters.
          1. soft, flattened body.
          2. hindwings pleated, wide, folded when over back, wings held flat over back at rest.
          3. antennae long, cerci present.
       4. Habitats. Nymphs aquatic in freshwater. Adults near water. Prefer streams or rocky shores.
       5. Food. Nymphs herbivorous, predaceous, omnivorous. Adults eat bluegreens or do not feed.
       6. Other. Nymphs with branched gills on thorax. Courting involves drumming of abdomen of males on substrate to attract females. Many emerge in winter or early spring.
   17. Zoraptera.
       1. Size - up to 3 mm.
       2. 2 spp. in N. A.
       3. Diagnostic characters.
          1. Antennae beadlike (moniliform).
          2. w/o wings then w/o eyes, with wings then with eyes.
          3. soft, pale colored body.
       4. Habitat. In piles of sawdust, under bark, in rotting logs.
       5. Food. Fungal spores, small dead arthropods.
       6. Other. None in Michigan, occur in southern states.
   18. Psocoptera (Book and Barklice). Start of Hemipteroid or Hemimetabolous orders.
       1. Size - mostly < 6 mm.
       2. about 340 spp. in N. A.
       3. Diagnostic characters.
          1. small, soft-bodied.
          2. swollen clypeus.
          3. if winged, held rooflike over back.
          4. long antennae, no cerci.
       4. Habitat. In dwellings in books and papers, under bark, dead leaves.
       5. Food. Algae, lichens, molds, cereals, pollen, dead insects.
       6. Other. Not true lice, name misleading. Not generally considered pests.
   19. Phthiraptera (Lice).
       1. Size - < 4 mm.
       2. about 1000 spp. in N. A.
       3. Diagnostic characters.
          1. ectoparasitic on birds and mammals.
          2. short antennae.
          3. wingless.
       4. Habitat. Ectoparasitic on birds and mammals.
       5. Food. Blood or bits of hair, feathers or skin of host.
       6. Other. Often put in two orders, Mallophaga (chewing lice), mainly on birds, and Anoplura (sucking lice), mainly on mammals.
   20. Hemiptera (True bugs).
       1. Size - variable.
       2. about 3,500 spp. in N. A.
       3. Diagnostic characters.
          1. forewings 1/2 leathery, 1/2 membranous, wings held flat over body at rest.
          2. sucking (haustellate) mouthparts from front of head.
          3. antennae fairly long.
       4. Habitats. Nearly all, terrestrial and aquatic.
       5. Food. Herbivorous and predaceous depending on family and species.
       6. Other. Some have wings reduced or absent.
   21. Homoptera (Cicadas, Hoppers, Psyllids, Whiteflies, Aphids, Scales).
       1. Size - variable.
       2. about 6300 spp. in N. A.
       3. Diagnostic characters.
          1. forewings membranous, wings held rooflike at rest.
          2. sucking mouthparts arising from back of head.
          3. antennae long or short.
       4. Habitats. On all types of plants.
       5. Food. Nearly all are phloem feeders, except cicadas which use xylem.
       6. Other. Many have degenerate or arrested development and are wingless, almost go through metamorphosis.
   22. Thysanoptera (Thrips). End of Hemipteroid orders.
       1. Size - 0.5 to 5 mm.
       2. about 700 spp. in N. A.
       3. Diagnostic characters.
          1. wings when present long, narrow with long fringe.
          2. sucking mouthparts.
          3. short antennae.
       4. Habitats. On flowers and other plant parts, under bark, in leaf litter, on fungi.
       5. Food. Many are herbivorous on flowers, leaves, fruits, twigs, buds; some eat fungal spores; some predaceous.
       6. Other. Development is intermediate between hemi- and holometabolous. Wings start development internally and have quiescent pupal stage.
   23. Neuroptera (Alderflies, Dobsonflies, Fishflies, Snakeflies, Lacewings, Antlions, Owlflies). Start of Holometabolous orders.
       1. Size - variable.
       2. about 350 spp. in N. A.
       3. Diagnostic characters.
          1. wings with many veins, numerous costal cross-veins, membranous, fore and hindwings often similar in size and shape.
          2. soft-bodied.
          3. antennae long.
          4. tarsi 5 seg.
       4. Habitats. Larvae both terrestrial and aquatic. Adults near these habitats.
       5. Food. Mostly predaceous in larval and adult stages.
       6. Other. Often put in 2 or 3 orders based on larval characters. Mouthparts mandibulate. Weak fliers.
   24. Coleoptera (Beetles).
       1. Size - variable.
       2. about 30,000 spp. in N. A.
       3. Diagnostic characters.
          1. forewings hardened as protective covers, elytra.
          2. chewing mouthparts.
       4. Habitats. Found nearly everywhere.
       5. Food. Feed on nearly everything.
       6. Other. By far our most speciose order.
   25. Strepsiptera (Twistedwing parasites).
       1. Size - < 5mm.
       2. about 100 spp. in N. A.
       3. Diagnostic characters.
          1. male freeliving, with fanlike hindwings, reduced forewings.
          2. female wingless, legless, arrested development.
       4. Habitats. Habitats of hosts.
       5. Food. Parasitic on Orthoptera, Hemiptera, Homoptera, Hymenoptera, Thysanura.
       6. Other. Female produces larvae which leave her body onto substrate (e.g. flowers). These are active and hop onto host when it visits area. Enters host and feeds in body cavity. Males emerge and flies, females stay in body of host and emit pheromone to attract males. May or may not kill host.
   26. Mecoptera (Scorpionflies and Hangingflies).
       1. Size - 9 to 22 mm.
       2. about 70 spp. in N. A.
       3. Diagnostic characters.
          1. head prolonged as beak.
          2. wings similar in size and shape.
          3. male of some have last genital segment modified to look like scorpion sting.
       4. Habitats. Wooded, moist areas.
       5. Food. Dead insects, some predaceous, some herbivorous.
       6. Other. Only holometabolous insect with larvae that have compound eyes. Some are found in middle of winter on snow. Have interesting mating behaviors.
   27. Siphonaptera (Fleas).
       1. Size - most less than 5 mm.
       2. about 320 spp. in N. A.
       3. diagnostic characters.
          1. wingless.
          2. laterally flattened.
          3. short antennae.
          4. enlarged coxae.
          5. ectoparasitic on birds and mammals.
       4. Habitats. Habitats of hosts. Typically larvae in nest or den.
       5. Food. Larvae feed on debris and detritus in nest or den. Adult feeds on blood of host.
       6. Other. Have sucking mouthparts. Many are host-restricted. May spend all time on host or just when feeding. Jumping insects. Important disease vectors (plague).
   28. Diptera (Flies).
       1. Size - variable.
       2. about 18,200 spp. in N. A.
       3. Diagnostic characters.
          1. only forewings developed.
          2. hindwings represented by halteres, equilibrium organs.
          3. sucking mouthparts.
       4. Habitats. Occur in most habitats. Many larvae aquatic.
       5. Food. Variable, herbivorous, predaceous, parasitic, blood feeding, carrion feeding, etc.
   29. Trichoptera (Caddisflies).
       1. Size - variable.
       2. about 1250 spp. in N. A.
       3. Diagnostic characters.
          1. mothlike wings with hairs, not usually scales.
          2. mandibulate mouthparts.
          3. antennae usually very long.
       4. Habitats. Larvae aquatic in fresh water. Adults nearby.
       5. Food. Larvae herbivorous or predaceous. Adults feed on liquid food or do not feed.
       6. Other. Generally dull-colored, wings held rooflike over abdomen. Many larvae make cases or nets. Important as food for other organisms.
   30. Lepidoptera (Butterflies and Moths).
       1. Size - variable.
       2. about 11,300 spp. in N. A.
       3. Diagnostic characters.
          1. wings large, scaly.
          2. sucking mouthparts.
       4. Habitats. Occur in most habitats, few are aquatic.
       5. Food. Larvae herbivorous, a few predaceous and detritivores. Adults feed on nectar, sap, dung.
       6. Other. Many are pests as larvae. Some beneficial as pollinators.
   31. Hymenoptera (Sawflies, Wasps, Ants, Bees).
       1. Size - variable.
       2. about 17,200 spp. in N. A.
       3. Diagnostic characters.
          1. wings membranous, hindwing with hamuli to connect to forewing.
          2. mouthparts mandibulate.
          3. abdomen often constricted between 1st and 2nd segement (wasp waist).
       4. Habitats. Occur in most terrestrial habitats.
       5. Food. Many parasitoids on other arthropods, sawflies herbaceous, some predaceous. Adults often feed on nectar and pollen.
       6. Other. Perhaps most beneficial to humans because of parasitism and pollination. Females often have long ovipositor which is sometimes represented by a sting.

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