258 SYSTEMATIC ZOOLOGY. 



Almost all the Hemiptera, when adult, have four wings, 

 though there are a number of wingless forms. These 

 wings are built upon two distinct patterns, and this serves 

 as a means of subdividing the Hemiptera into two groups. 

 In the one (HETEROPTERA) the basal half of the anterior 

 pair of wings is thickened while the rest is membranous, 

 and the wings themselves are held in an overlapping man- 

 ner upon the back when at rest. This condition is familiar 

 in the squash-bug. In the other group (HOMOPTERA) 

 there is no such thickening of the basal portion of the first 

 pair of wings, and these organs, when at rest, are placed 

 upon the sides of the abdomen. 



While most of the bugs are injurious to human interests, 

 there are some which are a benefit to man, since they feed 

 on injurious insects; and still others, like the cochineal- 

 and lac-bugs, produce substances of value to man. 



Of the HETEROPTERA some are aquatic, and of these 

 the water-skaters, gliding over the surface of still water, 

 are familiar to all. Others live most of their lives beneath 

 the surface, and some of the larger of these water bugs, 

 especially those called 'electric-light bugs,' can kill small 

 fish, sticking the beak into them and sucking their blood. 



Of the terrestrial forms none is more widely known than 

 the bedbug, a form which is famed for its attacks on man. 

 It is one of the bugs which never develop wings. From 

 the pecuniary standpoint the cinch-bug is more important, 

 since it attacks fields of grain, doing sometimes millions of 

 dollars of damage in a single year. The young attack first 

 the roots and underground stems, and later the stems them- 

 selves, killing them before they have had time to ripen the 

 grain. 



The squash-bug, which does such damage to pumpkin- 

 and squash-vines, is another form of Heteropteran, as are 



