WEEK 4 - KEYING OUT INSECT ORDERS:

Proper taxonomic identification of insects usually requires the use of a dichotomous key. Such keys compare physiological structures of an unknown insect to those of an insect whose taxonomy has been previously determined. These keys can be used to determine an insect's order, family, genus, and species, but for this lab, the key you will use (Study of Insects, 7th edition, pp. 157-167) is restricted to the determination of insect orders only. Starting at steps 1 and 1', decide which description BEST fits your unknown insect and progress onto the next step indicated by the key. Continue in this way, moving from step to step, until the key indicates the order of your unkown insect specimen. NOTE: The description in each step may not EXACTLY match your unknown insect so choose the description that BEST matches your insect. Numbers in brackets (#) indicate which step led you to the step you are currently on. Descriptions in bold are those which best match the current example. Asterisks* indicate groups that are unlikely to be encountered by the general collector.

EXAMPLE 1, ORDER LEPIDOPTERA:

1. With well-developed wings (adults) 1'. Wingless or with wings vestigial or rudimentary (nymphs, larvae, and some adults)	2 28
2(1). Wings membranous, not hardened or leathery 2'. Front wings hardened or leathery, at least at base; hind wings, if present, usually membranous	3 23
3(2). With only 1 pair of wings 3'. With 2 pairs of wings	4 10
10(3'). Wings largely or entirely covered with scales; mouthparts usually in form of coiled proboscis; antennae many-segmented (butterflies and moths) 10'. Wings not covered with scales; mouthparts not in form of coiled proboscis; antennae variable	Lepidoptera 11

EXAMPLE 2, ORDER DIPTERA:

1. With well-developed wings (adults) 1'. Wingless or with wings vestigial or rudimentary (nymphs, larvae, and some adults)	2 28
2(1). Wings membranous, not hardened or leathery 2'. Front wings hardened or leathery, at least at base; hind wings, if present, usually membranous	3 23
3(2). With only 1 pair of wings 3'. With 2 pairs of wings	4 10
4(3). Body grasshpper-like; pronotum extending back over abdomen and pointed apically; hind legs enlarged (pygmy grasshoppers, family Tetrigidae) 4'. Body not grasshoppper-like; pronotum not as in preceding item; hind legs not so enlarged	Orthoptera 5
5(4'). Antennae with al least 1 segment bearing a long lateral process; front wings minute, hind wings fanlike; minute insects (male twisted-winged parasites) 5'. Not exactly fitting the preceding description	Strepsiptera* 6
6(5'). Abdomen with 1-3 threadlike or stylelike caudal filaments; mouthparts vestigial 6'. Abdomen without threadlike or stylelike caudal filaments; mouthparts nearly always well developed, mandibulate or haustellate	7 8
8(6'). Tarsi nearly always 5-segmented; mouthparts haustellate; hind wings reduced to halteres (flies) 8'. Tarsi 2- or 3-segmented; mouthparts variable; hind wings reduced or absent, not haltere-like	Diptera 9

___________________________________________________________ All images and information appearing on this website are intended for educational purposes only, and are the exclusive property of their respective owners. Website created by Nathan Woodbury