56 The Classification of Insects 



D. Mandibles often rudimentary, when present bristle-like. 



E. Wings four (sometimes wanting), clothed with scales; body 

 covered thickly with scales or hairs; mouth, 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 halleres; 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 



