The Bulletin. 



15 



this beak the insect punctures the stem or tissue of the leaf and 

 sucks out the sap. The young lice are much like the grown ones in 

 appearance, and are represented at b and c in the figure. 



During cool, wet seasons the lice multiply rapidly and become 

 quite destructive, causing the infested plants to become stunted and 

 distorted. The insect also attacks melons, cucumbers, and no doubt 

 a number of species of weeds. In hot, dry seasons 'a number of other 

 insects, which feed upon the lice, become abundant and check them. 

 The lice are, . therefore, more abundant in cool seasons, not so much 

 because such a season is more beneficial to them, but because a cool 

 season is very unfavorable to the enemies which prey on the lice. 

 The grown lice may be either winged or wingless, as shown in 

 Fig. 5. 



Natural Enemies. — As already indicated there are a number of 

 other insects which prey on the Leaf-louse. Probably the most im- 

 portant of these are certain very small black four-winged flies (hardly 

 as large as the gnats which often get into the eyes of persons) which 

 sting the lice .and lay their eggs in the bodies of the lice. These 

 are known as parasites. In warm weather these parasites are very 

 active and may be found running about on the leaves in search 

 of suitable victims. If the farmer will notice closely he may often 

 find a considerable number of dead lice on the leaves which are dry 

 and brown and bloated in appearance. These have been killed by the 

 growth of the young parasite within their bodies. These parasites 

 are wholly unknown to, and unappreciated by, the average cotton 

 farmer, yet it is largely on account of their activity that the lice dis- 

 appear when hot weather comes on in early summer. 



Frequently the farmer will notice on the louse-infested cotton 

 a yellowish beetle with black spots. These beetles are about a fourth 

 of an inch long, and crawl about among the louse-infested leaves. 

 These are known as Lady-beetles, and the one most frequently found 

 on lousy cotton is the Convergent Lady-beetle (Hippodamia con- 

 vergent) shown in Fig. 6. 



a v 



Fig. 6. — Convergent Lady-beetle. An important enemy of the Cotton Leaf- 

 louse. Adult beetle at a, the young or larva at c, and the pupa at 6. 



(After Chittenden, Bur. Ent., U. S. Dept. Agr.) 



