Class Insecta -  {Backward Link}

 

 
 



NOTE: Descriptions, unless otherwise noted, refer to adult forms.


1a. Small and primitive. Lack wings or wing-like structures.
   
         Subclass Apterygota................................................................................. 2

1b. Have wings in some form (may appear has hard coverings over 
            abdomen), or have lost them through ancestor.  Includes more 
            advanced and larger insects. Subclass Pterogota................................ 3



2a. Small; usually have forked lever under body used for "jumping."
   
         Springtails.........................................................LINK..... Order Collembola

2b. Three thin projections from rear end; body seems scaly.
   
         Silverfish, Bristletails, Firebrats..........................LINK. Order Thysanura



3a
. Wings at rest held up or out, not folded back over abdomen........................ 4

3b. Wings usually can be folded back over the abdomen.................................... 5



4a. Three projections from rear end; front wings bigger and triangular,
   
         back wings smaller and rounded; wings held up at rest.
   
         Mayflies.........................................LINK................. Order Ephemeroptera

4b. Front and back wings close to same size and shape; wings held at
   
         rest out away from body. Dragonflies and Damselflies.
                    ............................................................LINK................. Order Odonata



5a.
Adults are very small and usually lack wings; often are parasites.
   
         Fleas and Lice............................................................................................... 6

5b. Thorax covered with shield-like pronotum; front wings leathery,
   
         with veins, held over rear wings................................................................. 10

5c. Various sizes; have four large leaf-shaped wings, all nearly equal in 
            size and with fine network of veins. Antennae usually long. 
            Order Neuroptera
..................................................................................... 12

5d. Somewhat fragile; wings usually quite broad, with front pair larger, 
            covered with scales, with few cross-veins.  Order Lepidoptera.......... 13

5e. Usually have wings; when present, most have four similarly-textured 
            wings, usually membranous but sometimes leathery; the front wings 
            are longer but the rear pair wider; wings do not overlap much at tip;
   
         small antennae; eyes often obvious. Order Homoptera....................... 14

5f. Similar to Homoptera, above, but, when wings are present, front 
            wings have forward section that is thick but back section that is 
            thin;  wings overlap each other; heads tend to be longer than
            Homopterans.
   "True Bugs."  Order Hemiptera.................................... 15

5g. Usually four smallish, membranous wings; hind wings smaller, 
            often connected to front wings; connection from thorax to 
            abdomen often narrow; stingers common, especially in females. 
            Order Hymenoptera
................................................................................. 18

5h. Body covering usually quite rigid, often shiny; front wings quite thick,
   
         meeting in straight line down middle of abdomen; only front thorax
   
         covering is distinct. Beetles.............LINK................... Order Coleoptera

5i. Body ant-like but without narrowing between thorax and abdomen;
   
         only reproductive kings and queens have wings; highly social, 
            eat wood. Termites..........................LINK.......................... Order Isoptera

5j. Small; live on flowers or other plant parts; long, narrow mouthparts;
   
         long wings with hair-like fringe. Thrips.....LINK..... Order Thysanoptera

5k. Cylindrical body; front legs modified for production of silk.
   
         Webspinners..............................LINK............................. Order Embiidina

5l. Large, pincer-like structures on abdomen; wings not easily seen.
   
         Earwigs..............................................LINK................... Order Dermaptera

5m. Long thin antennae. Stoneflies...................LINK.............. Order Plecoptera

5n. Moth-like but wings covered with hairs rather than scales.
   
         Caddisflies...............................................LINK............... Order Tricoptera

5o. Head and mouth parts lengthened into "snout;" long, somewhat 
            narrow wings with many cross veins; abdomen may curve up, 
            like scorpion tail. Scorpionflies.................LINK............ Order Mecoptera

5p. Only one pair of wings, the front pair, with knob-like halteres in place 
            of rear wings. Includes common House Flies and Mosquitoes.
                    .............................................................LINK................... Order Diptera



6a. Small, with bodies flattened side-to-side; legs well-adapted for
   
         jumping. Blood-sucking parasites. Fleas...LINK... Order Siphonaptera

6b. Quite small, usually yellow; long antennae. Some live in books, or on 
            tree bark. Book Lice, Bark Lice, Dust Lice...LINK.... Order Psocoptera

6c. Parasitic lice of mammals or birds. Order Phthiraptera.............................. 7



7a. Small, with broad, rounded heads. Found mostly on birds.
   
         Chewing Lice, Bird Lice.............LINK................. Suborder Mallophaga

7b. Small, with narrow, often pointed head. Legs heavy and specialized
   
         to hold on to mammal hairs. Sucking Lice. Suborder Anoplura........... 8



8a. Parasites of non-human mammals, including domestic mammals.
   
                 .......................................LINK..................... Family Haematopinidae

8b. Parasites;  found in human hair. Family Pediculidae..................................  9



9a. Human head lice.
Genus Pediculus........LINK.......... Pediculus humanus

9b. Human pubic lice. Genus Phthirius.............LINK.............. Phthirius pubis



10a.
Body is oval. Cockroaches..............................LINK............ Order Blattidae

10b. Body is long. Front legs with heavy spines and used for grabbing 
            prey.  Mantises...........................................KEY................ Order Mantidae

10c. Long, cylindrical, body; long antennae; long, stiff legs. No obvious
   
         wings. Walking Sticks, Walking Leaves......LINK......... Order Phasmida

10d. Rear legs with large "thigh" section (femur) for jumping.
   
         Order Orthoptera...................................................................................... 11



11a. Moderately long; generally active during the day. 
            Grasshoppers...............................................................
Family Locustidae

11b. Have very long antennae, sometimes longer than body.
   
         Includes katydids....................................................... Family Tettigoniidae

11c. Usually somewhat short bodies, but with moderately long antennae.
   
         Wing edges bent downward along front margin. Often dark;  active 
   
         mostly at night. Crickets.................................................... Family Gryllidae



12a. Moderate to large in size; large, squarish head and front of thorax;
   
         large wings, frequently with spots. Dobson Flies, Alder Flies,
   
         Fish Flies. Larvae aquatic, includes hellgrammites........ Family Sialidae

12b. Slender bodies, often leaf-green; eyes often yellow; long, very slender
   
         antennae; wings lacy with green veins; flight is fluttery.  Lace Wings,
            Aphid Lions, Golden-Eyed Flies.............................. Family Chrysopidae

12c. Long, slender abdomens, often longer than wings; short, clubbed
   
         antennae; short, weak legs. As larvae, build trap pits to prey on 
            ants and other insects. Ant Lions, Doodle Bugs.
                    ....................................................................... Family Myrmeleontidae



13a. Wings connected by finger-like projection of front wing over front
   
         margin of rear wing; vein patterns in both wings similar.  Never 
            with coiled, siphoning mouthparts.  Mandibulate Moths, Swift
            Moths.............................................................................. Suborder Jugatae

13b. Wings connected by bristles or membrane from the hind wing over
   
         rear of front wing; mouthparts usually siphoning; abdomen heavy. 
            Mostly night fliers. Includes most moths.................... Suborder Frenatae

13c. Wings at rest usually held vertically above body and in contact with 
            each other; in flight, wings held together by membrane near base 
            of rear wings; antennae commonly thicker near tip.
   
         Butterflies and Skippers...................................... Suborder Rhopalocera



14a. Small to large; wedge-shaped, broad heads, with triangular face 
            and eyes that bulge to the sides; abdomen tapers; males make
   
         loud mating calls. Cicadas............................................. Family Cicadidae

14b. Front thorax covering may be many various shapes, may be 
            prolonged, enlarged. Overall, varied and odd-looking. 
            Treehoppers.............................................................. Family Membracidae

14c. Brown, oval bodies, with wings of similar color; head flat on top; 
            rear legs with stout spines. Young produce frothy material around
   
         plants they feed on. Spittle Bugs................................ Family Cercopidae

14d. Often similar to 14c but with antennae directly beneath eyes; 
            antennae have thick bottom 2 segments, then are thin. 
            Planthoppers.................................................................. Family Fulgoridae

14e. Look superficially like leafhoppers; hind legs built for leaping; often
   
         have yellow spots; antennae project horn-like from in front of eyes 
            and end in 2 short hairs. Jumping Plant Lice............. Family Chermidae

14f. Quite small; often wingless; short head and thorax, swollen and soft 
            abdomen, with tubes on 5th or 6th segment for oil/wax secretion; 
            long, slender antennae; vast majority are female.
   
         Aphids or Plant Lice....................................................... Family Aphididae

14g. Quite small; wings moth-like and white. Whiteflies..... Family Aleyrodidae

14h. Females may be wingless and legless; males gnat-like.
   
         Scale Insects and Mealy Bugs....................................... Family Coccidae



15a. Antennae shorter than head, often concealed underneath;
   
         commonly found underwater. Suborder Cryptocerata........................ 16

15b. Antennae at least as long as head and visible at sides; often produce
            noxious odor; not underwater. Suborder Gymnocerata...................... 17



16a. Head broad and rounded; rear legs long and used like oars;
   
         swim with back up. Water Boatmen.............................. Family Corixidae

16b. Similar to 16a. but swim with belly up. Back Swimmers.
                    ........................................................................... Family Notonectidae

16c. Long, stick-like bodies; often with long tail "snorkel;" front legs 
            hinged like pocketknife. Water Scorpions...................... Family Nepidae

16d. Large, hard, broad body; middle and hind legs flattened, somewhat
            oar-like. Predatory bloodsuckers. Giant Water Bugs.
                    ........................................................................... Family Belostomidae



17a. Slender body; long, thin legs with water-repellent hairs on feet.
   
         Water Striders.................................................................... Family Gerridae

17b. Oval, somewhat flattened; rigid beak bent back under thorax.
   
         Assassin Bugs, Kissing Bugs..................................... Family Reduviidae

17c. Rounded bodies; wings difficult to see; thorax narrows between
   
         front and middle legs. Bedbugs..................................... Family Cimicidae

17d. Slender, straight-sided body; long, slender legs and very thin
   
         antennae; long, narrow head with bulging eyes.
   
         Damsel Bugs..................................................................... Family Nabidae

17e. Body somewhat "8"-shaped; front legs quite thick; short antennae
   
         with thickened end segment; wings narrow, often not covering 
            full width of abdomen. Ambush Bugs........................ Family Phymatidae

17f. Broad, flat body, somewhat shield-shaped; thorax covering
   
         (scutellum) long and pointed; legs somewhat short;  antennae 
            slender, 5 segments. May be quite colorful;  may produce very 
            bad odor. Stink Bugs............................................... Family Pentatomidae

17g. Body a long oval, often covered with fine hairs; short, downbent
   
         head; antennae long, 4 segments, first often thickened;  long 
            hind legs. Leaf Bugs............................................................. Family Miridae

17h. Entire body often covered with fine veins; commonly have ridges 
            and knobs on front on thorax; head short; wings much wider than
   
         abdomen. Found on undersides of leaves. Lace Bugs. Family Tingidae

17i. Body narrowly oval or straight-sided; wing membrane with 4 or 5 
            long, unbranched veins; head somewhat broad and short; often 
            marked with "X." Chinch Bugs...................................... Family Lygaeidae

17j. Body shapes vary; head with bulging eyes usually tapers to neck,
   
         then thorax widens; legs and antennae often have thickened
   
         segments; wing membrane distinct in color and texture.
   
         Includes Squash Bugs...................................................... Family Coreidae



18a.
No narrowing between thorax and abdomen; have no stings; 
            female's ovipositors adapted for sawing or boring. Horn-Tails,
   
         Stem Sawflies, and Sawflies......................... Suborder Chalastogastra

18b. Definite narrowing between thorax and abdomen; stings common.
   
         Suborder Clistogastra............................................................................ 19



NOTE:
Only more common Clistogastra Families Listed

19a. Hairs on body are not branched. Often wingless. Ants. Family Formicidae

19b. Hairs on body not branched; bodies often somewhat slender;
   
         thorax-abdomen connection often quite narrow. Usually
   
         predators. Wasps and Wasp-like forms.................................................. 20

19c. Much hairier than 19a. or 19b., with hairs that are branched or puffy;
            bodies often stout, rounded; often have structures on legs for 
            gathering pollen. Bees................................................................................ 21



20a. Can be quite large; abdomen often very long; female ovipositor
   
         always visible and can be quite long; antennae long, thin, and 
            vibrate constantly in life. Larvae are parasitic, usually on 
            caterpillars. Ichneumon Wasps........................... Family Ichneumonidae

20b. Similar to 20a. but tend to be smaller with shorter abdomen 
            and thicker antennae. Braconid Wasps.................... Family Braconidae

20c. Usually quite small to tiny; abdomen usually short and round; 
            often metallic colored; body hairs rare; antennae bent; wings 
            with few or no veins. Thousands of species. Chalcid Wasps.
                    ............................................................................... Family Chalcididae

20d. Usually small to tiny; abdomen often flattened from sides; usually 
            dull in color; antennae straight and usually long. Gall Wasps.
                    .................................................................................. Family Cynipidae

20e. Usually beautifully colored; varied shapes but often with long, 
            narrow "waist;" head usually broad. Includes Digger Wasps 
            and
Mud-Daubers.......................................................... Family Sphecidae

20f. Large, with polished but not shiny surface; usually black but may 
            be striped; very long hind legs. Commonly prey upon spiders,
   
         but includes Cicada Killer Wasps. Spider Wasps.... Family Pompilidae

20g. Usually large; commonly marked with yellow bands on dark back-
            groundthorax-abdomen connection not as narrow as other wasps.
   
         Commonly social, forming large nests. Includes Paper Wasps,
   
         Hornets, and Yellow-Jackets........................................... Family Vespidae



21a. Very large heads with scissors-like mandibles; highly polished 
            black, blue, or green bodies, sometimes with thin white stripes.
   
         Leaf-Cutting Bees and Mason Bees...................... Family Megachilidae

21b. Quite large; blackish or bluish-brown; resemble bumblebees but 
            less hairy, with more flattened bodies. Large Carpenter Bees.
                    ............................................................................. Family Xylocopidae

21c. Fairly small; black or metallic blue-green; body regions are well
   
         separated; about 5 times longer than wide.  Small Carpenter
            Bees.............................................................................. Family Ceratinidae

21d. Various colors, including metallic red, black, blue, green, and copper;
   
         usually not striped or spotted; not very hairy. Includes most bees 
            seen that are not honeybees. Includes Mining Bees and
   
         Sweat Bees.................................................................. Family Andrenidae

21e. Quite large and hairy; black and yellow or black and red hairs;
   
         distinctly round. Bumblebees..................................... Family Bombinidae

21f. Very social, occupying large hives; hairy thorax and orangish to
   
         reddish abdomen. Honeybees............................................ Family Apidae

 



 
     

 


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First Written 1986;  Last Update 2011;  Web Version 2001,  M. McDarby

 

 

 

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