2 60 THE STUDY OF INSECTS. 



ness and the great reduction of the anal area (Fig. 305) ; 

 while the hind wings have a widely expanded anal area. 

 There is great variation within the family in the number of 

 anal veins in the hind wings, the number ranging from two 

 to four. The maximum number of anal veins in the Lepi- 

 doptera has generally been considered to be three ; but in 

 certain forms belonging to this family a fourth (vein X) is 

 quite well represented. 



Another remarkable feature of all tne forms that we 

 have studied is that in the female the bristles composing 

 the frenulum are consolidated as in the male. The females 

 also possess a frenulum hook ; but this is not so highly 

 specialized as that of the male. 



The adults fly very swiftly and during the hotter part of 

 the day. They frequent flowers, thus increasing their resem- 

 blance to bees or wasps. The larvae are borers, living within 

 the more solid parts of plants. Some species cause serious 

 injury to vegetation. Nearly one hundred and fifty species 

 have been found in this country. Doubtless many more 

 exist ; for the family has not been thoroughly studied as yet. 

 The following species have attracted much attention on 

 account of their serious ravages. 



The Peach-tree Borer, Sannina exitiosa (San-ni'na ex-it-i- 

 o'sa). This is the most important insect enemy of the 

 peach-tree. In some parts of the country it is difficult to 

 find a peach-tree that is not infested by it. The eggs are 

 laid on the bark of the tree near the ground. The larvae 

 bore downward in the bark of the trunk just below the sur- 

 face of the ground. Their burrows become filled by a 

 gummy secretion of the tree. As this oozes out in large 

 masses the presence of the borer is easily detected by it. 

 When full grown the larva comes to the surface of the 

 ground and makes a cocoon of borings fastened together 

 with silk. The perfect insects appear from May till October, 

 but most of them in the latter part of June and early in 

 July. There is a single generation each year. The adults 



1 -' 



