170 



APPLIED ENTOMOLOGY 



clusters on leaves, twigs or in other places. The eggs themselves vary 

 much in appearance, some being provided with circlets of spines, some 

 with long filaments and some being smooth but of unusual form or color. 

 They hatch into nymphs (Fig. 161) more or less closely resembling the 

 adult, which stage they reach by a series of molts, changing with each 

 molt. 



The Order Hemiptera may be characterized as: 



Insects which when adult nearly always have four wings, the front pair 

 in most cases partly horny, partly membranous: with a plate located between 

 the bases of the wings, usually triangular in outline, in some cases covering 

 more or less of the abdomen above: mouth parts for sucking, and attached to 

 the front end of the underside of the head. Metamorphosis incomplete. 



FIG. 161. Metamorphosis of the Squash Bug (Anasa tristis De G.) : adult and nymphs 

 of different ages, all twice natural size. (From Folsom.) 



Hemiptera occur under almost every conceivable condition of life. 

 Some live in water, coming to the surface only to obtain air: some are 

 found on the surface of the water and some are found on the ocean hun- 

 dreds of miles from land. Most of the group are terrestrial, however, and 

 in many cases are widely distributed. Probably fifteen thousand species 

 are already known but the group has been little studied as compared 

 with some of the more attractively colored and marked orders. Those 

 living in water are at least for the most part, feeders on insects and other 

 animals small enough for them to capture : those which live on the surface 

 are also predaceous, while of the land forms some consume other insects 

 but probably the larger number are plant feeders. The Hemiptera are 

 the true bugs, the general use of the term "bug" as applied to all insects 

 being incorrect. 



