184 



Bulletin 87 



found in excessive abundance in Arizona cotton fields, the insects 

 had first attacked the ground cherry and turned their attention to 

 the cotton plants only after they had completely stripped the weeds. 

 The salt marsh caterpillar is one of those commonly known as 

 "woolly bears." The hairs are black and red. The general appear- 

 ance of the caterpillar and moths is well shown in the illustration. 



THE COTTON LEAF PERFORATOR 



A very conspicuous type of insect injury to cotton plants is pro- 

 duced by the larvae of a tiny moth which has a wing expanse of 



Fig. 11 — The cotton leaf perforator: 1, adult. 2, pupa skin attached to cocoon. 

 3, cocoon of leaf perforator. 4, cocoon of salt marsh caterpillar. 



only about a third of an inch. The larvae during the first stages 

 are so small tliat they live inside the leaf tissue where they pro- 

 duce a serpentine mine. W'hen nearly full grown they eat their 

 way to the surface of the leaf and during the last stage feed on the 

 surface of the leaves in which they make small perforations. On 

 account of this injury, which suggests the eft'ect of small shot from 

 a shotgun, the common name "cotton leaf perforator" (Buccnlatrix 

 thnrherieUa Busck) has been suggested. During the period when 

 the larva is living on the surface of the leaf it molts once. This 



