56 
The Classification of Insects 
D. Mandibles ojten rudimentary, when present bristle-like. 
E. Wings four (sometimes wanting ), clothed with scales; body 
covered thickly with scales or hairs; mouthy when developed, a 
slender sucking proboscis, closely coiled under head. 
(Moths and butterflies.) Lepidoptera. 
EE. Wings two {or wanting), naked or with scattered hairs; hind 
wings in winged forms represented by halteres; body either 
naked or with scattering hairs; mouth a soft or horny beak, not 
coiled under head. 
F. Prothorax poorly developed, scarcely visible from dorsal 
side .;. (Flies.) Diptera. 
FF. Prothorax well developed, distinctly visible from dorsal 
side; wings never present.(Fleas.) Siphonaptera. 
DD. Mandibles well developed, fitted for biting; wings four {sometimes 
two or none), naked or with scattered hairs. 
(Ichneumon-flies, gall-flies, wasps, bees, and ants.) Hymenoptera. 
After one has classified an insect in its proper order there remains, first, 
the determination of the family (each order being composed of from one 
to many families), then of the genus (each family comprising one to many 
genera), and finally of the particular species of the genus (each genus includ¬ 
ing one to many species). This ultimate classification to species, however, 
will be possible to the amateur in comparatively few cases. There are so 
many species of insects (about 300,000 are known) that it would require 
many shelves of books to contain the descriptions of them all. As a matter 
of fact, in only a few orders have the descriptions of the species been brought 
together in manuals available for general students. For the most part the 
descriptions are scattered in scientific journals printed in various languages 
and wholly inaccessible to the amateur. There are less than 1000 different 
species of birds in North America; there are more than 10,000 known 
species of beetles. Now when one recalls the size of the systematic man¬ 
uals of North American birds, and realizes that ten such volumes would 
include only the insects of one order, it is apparent that complete manuals 
of North American insects are out of the question. Except in the case of 
the most familiar, wide-spread, and readily recognizable insect species we 
must content ourselves with learning the genus, or the family, or with the 
more obscure, slightly marked* and difficult members of certain large groups, 
as the beetles and moths, simply the order of our insect specimens. 
When one has determined the order of an insect by means of the above 
key he should turn to the account of this particular order in the book (see 
index for page) and find the keys and aids to the further classification of 
the specimen which the author has thought could be used by the general 
student. Comparison with the figures and brief descriptions of particular 
species which are given in each order may enable the amateur to identify 
the exact species of some of his specimens. But the specific determination 
