Key to Insect Orders

Created 1995 using Peterson Field Guides: Insects (c. 1970) by Stan and Trish Smith, Warrensburg R-VI Schools

updated 9/2/04 by Dr. Stephen Wilson, Central Missouri State University

 

            1a.       Wings present (may be hardened and covering hindwings) - Go to 2

            1b.       Wings absent - Go to 22

 

            2a.       Wings covered in flattened scales - Lepidoptera

            2b.       Wings not covered in scales (may be hairy) - Go to 3

 

            3a.       One pair of wings - Diptera

            3b.       Two pair of wings (hindwings may be covered by forewings) - Go to 4

 

            4a.       Wings long, narrow and fringed with long hairs, abdomen broadly attached to thorax,

small insects (< 5mm) - Thysanoptera

            4b.       Wings not long, narrow and fringed; usually larger insects (> 5mm); if small with fringed

wings then abdomen narrrowly attached to thorax - Go to 5

 

            5a.       Forewings triangular, abdomen with 2 or 3 long tails - Ephemeroptera 

            5b.       Forewings not triangular - Go to 6

 

            6a.       Sucking mouthparts - Hemiptera

            6b.       Chewing mouthparts - Go to 7

 

            7a.       Forewings much longer and larger than hindwings, not hardened and covering hindwings -

Go to 8

            7b.       Forewings nearly the same size or shorter than hindwing, may be hardened or leathery and

covering hindwings - Go to 10

 

            8a.       Moth-like, forewings opaque and hairy, antennae longer than body - Trichoptera

            8b.       Not moth-like, forewings translucent, antennae shorter than body - Go to 9

 

            9a.       Front of head appears bulbous and swollen, tarsi (ÒfeetÓ) with 2 or 3 segments - Psocoptera

            9b.       Front of head not swollen, tarsi (ÒfeetÓ) with 5 segments, abdomen usually narrowly

attached to thorax (wasp-like or bee-like) - Hymenoptera

 

            10a.     Forewings hardened and covering hindwings - Go to 11

            10b.     Forewings membranous or leathery - Go to 12

 

            11a.     Abdomen with large, forcep-like appendages - Dermaptera

            11b.     Abdomen without forcep-like appendages - Coleoptera

 

            12a.     Head with beak-like projection - Mecoptera

            12b.     Head without beak-like projection - go to 13

 

            13a.     Abdomen with two long tails - Plecoptera

            13b.     Abdomen without two long tails - Go to 14

 

            14a.     Antennae shorter than the head - Odonata

            14b.     Antennae longer than the head - Go to 15

            15a.     Moth-like, forewings opaque and hairy, antennae longer than body - Trichoptera

            15b.     Not moth-like, forewings usually not hairy - Go to 16

 

            16a.     Body twig-shaped - Phasmatodea

            16b.     Body not twig-shaped - Go to 17

 

            17a.     Hind legs modified for jumping or front legs modified for digging - Orthoptera

            17b.     Neither hind legs or front legs modified as above- Go to 18

 

            18a.     Forewings with many cross veins between edge of wing and first longitudinal vein - Go to

19

            18b.     Forewings with very few cross veins between edge of wing and first longitudinal vein - Go

to 20

 

            19a.     Forewings narrower at base than hindwings; large insects (> 10 mm) and usually brown or

black in color - Megaloptera

            19b.     Forewings as broader or broader at base than hindwings; smaller insects (usually < 10 mm)

and usually green, yellow, or light brown in color - Neuroptera

 

            20a.     Fore- and hindwings translucent and identical in size and venation - Isoptera

            20b.     Fore and hindwings leathery and not identical in size - Go to 21

 

            21a.     Front legs raptorial, modified for capturing prey - Mantodea

            21b.     Front legs not raptorial - Blattodea

 

            22a.     Abdomen narrowly attached to thorax, ant-like or wasp-like - Hymenoptera

            22b.     Abdomen broadly attached to thorax, not ant-like or wasp-like - Go to 23

 

            23a.     Abdomen with forked tail, small insects (< 5 mm) - Collembola

            23b.     Abdomen without forked tail - Go to 24

 

            24a.     Body flattened laterally, external parasites -  Siphonaptera

            24b.     Body not flattened laterally - Go to 25

 

            25a.     Parasites on birds or mammals - Go to 26

            25b.     Free-living, not parasites of birds or mammals - Go to 28

 

            26a.     Tarsi (ÒfeetÓ) with 5 segments - Diptera

            26b.     Tarsi (ÒfeetÓ) with fewer than 5 segments - Go to 27

 

            27a.     Anennae longer than head - Hemiptera

            27b.     Antennae shorter than head - Phthiraptera

 

            28a.     Abdomen with long tails - Go to 29

            28b.     Abdomen without long tails  - Go to 30

 

            29a.     Body hump-backed - Archeognatha

            29b.     Body not hump-backed - Thysanura

 

 

            30a.     Sucking mouthparts - Hemiptera

            30b.     Chewing mouthparts - Go to 31

 

            31a.     Front of head appears bulbous and swollen,  antennae almost as long as body or longer -

Psocoptera

            31b.     Front of head not bulbous and swollen, antennae usually much shorter than body - Go to

32

 

            32a.     Body white, not very slender - Isoptera

            32b.     Body colored - Go to 33

 

            33a.     Small insects (< 5 mm), body very narrow, slender - Thysanoptera

            33b.     Larger insects (> 5mm), body not narrow, slender (may be worm-like or caterpillar-like) -

Go to 34

 

            34a.     Hind legs modified for jumping or front legs modified for prey capture or digging - Go to

35

            34b.     Legs not modified as above - Go to 36

 

            35a.     Hind legs modified for jumping or front legs modified for digging - Orthoptera

            35b.     Front legs modified for prey capture - Mantodea

 

            36a.     Body twig-like - Phasmatodea

            36b.     Body not twig-like - Go to 37

 

            37a.     Body worm-like or caterpillar-like, with or without legs - insect larvae

            37b.     Body not worm-like or caterpillar-like, with legs, with wingpads - insect nymphs

           

 

Note:   This key should work for most insects.  The following orders are very rare and unlikely to be collected by students and, thus, are not included in the key:  Protura, Diplura, Grylloblattodea, Embiidina, Zoraptera, Raphidioptera, and Strepsiptera.

INSECT ORDERS AND THEIR COMMON NAMES

 

Archeognatha               Jumping Bristletails

Blattodea                      Cockroaches

Coleoptera                    Beetles

Collembola                   Springtails

Dermaptera                  Earwigs

Diptera                         Flies

Ephemeroptera             Mayflies

Hemiptera                    True Bugs, Cicadas, Hoppers, Aphids, Scale Insects

Hymenoptera               Ants, Wasps, Bees, Sawflies

Isoptera                        Termites

Lepidoptera                  Butterflies and Moths

Mantodea                     Mantids

Mecoptera                    Scorpionflies

Megaloptera                 Dobsonflies, Fishflies, and Alderflies

Neuroptera                   Snakeflies, Lacewings, and Antlions

Odonata                       Dragonflies and Damselflies

Orthoptera                   Grasshoppers, Katydids, Crickets

Phasmatodea                Walking Sticks

Phthiraptera                Human Lice

Plecoptera                    Stoneflies

Psocoptera                    Booklice and Barklice

Siphonaptera                Fleas

Thysanoptera               Thrips

Thysanura                    Silverfish and Firebrats

Trichoptera                  Caddisflies