THE CLASSIFICATION OF INSECTS 179 



fliers, and which have their antennae slender and thread-like 

 with the tip thickened so as to form a small spindle-shaped 

 club; the Hesperina, or skippers, which are also day fliers and 

 which have the antennas slender and with slightly expanded 

 or hooked tip; and the Heterocera, or moths, most of which 

 are night fliers, and which have their antennas variously formed, 

 either entirely thread-like or with some of the segments pro- 

 vided with many long hairs arranged so as to make the antennae 

 look like a flat brush. The Heterocera include by far the 

 greater number of species of Lepidoptera, and many of the 

 more obscurely colored ones are rarely seen. They vary in 

 size from the small clothes-moths and leaf-miners to the great 

 Cecropias and Lunas. Colored pictures of most of the more 

 common kinds of moths and butterflies can be found in nature 

 books, and the different species can readily be determined by 

 referring to these pictures. A number of the species with 

 injurious caterpillars are described in Chapters XXX to 

 XXXVII. 



Order Hymenoptera. The Hymenoptera are a large order, 

 which includes, besides the popularly known ants, bees and 

 wasps, many less familiar insects showing much variety in 

 appearance and habit, 7500 species being found in this coun- 

 try alone. Many of these are parasites, spending their larval 

 life within the bodies of other insects, feeding on their tissues 

 and finally destroying them. Because of the great importance 

 of these parasites in keeping noxious insects in check, and 

 because of the gifts from the honey-bee and the innocuous 

 character of most of the other members of the order, the 

 Hymenoptera may be looked on as the chief beneficial order of 

 insects. 



Few generalizations can be made that will apply to all 

 members of the order although there is no question concerning 

 the true relationship of all the kinds of insects included in it. 

 The name of the order is derived from the clear membranous 

 condition of the two pairs of wings (hymen, membrane, ptera, 

 wings). The front wings are larger than the hind ones and 

 all are provided with comparatively few branched veins. 

 The workers of all the ant species are wingless as are also the 



