As an aid to the beginner in making preliminary identification of his
specimens and also as an aid in arranging his collection, a short
descriptive synopsis of the orders of living insects is given below. In
this description are noted the most distinctive features of the common
insects occurring in Illinois. There are rare and obscure forms, seldom
met by the collector, that require a more technical key for their
identification; for these the collector will need to consult some of the
more nearly complete books listed on page 70. The collector will find,
however, that this synopsis will afford a beginning for his
classification of the common forms.
Various characters are used to identify an insect to family, genus, and
species. Among these characters are the antennae, wings (if present),
legs, and mouthparts. Frequently important for identification are such
minute details as hair or scales covering the body or wings and the
texture of these parts. In most cases good microscopic equipment is
necessary to see clearly the characters used in the diagnosis of
insects.