Insect Pests of Interest to Cotton Growers 



197 



importance as a cotton pest on account of the effectiveness of its 

 natural enemies, particularly a black wasp-like parasite. 



There are two forms of the adult, winged and wingless females. 

 Males are not known. The body of one of the full grown insects 

 is about a fifteenth of an inch long. The folded wings in the case 

 of the winged form extend approximately another fifteenth inch 



(DUt. 



^.. -Ob. 



Pig. 24 — The cotton aphis. 



beyond the end of the body. The migrating or winged adults 

 spread into the cotton fields from mallow and other weeds which 

 have remained infested throughout the wanter. Eggs are laid on 

 the young cotton plants soon after they come through the ground. 

 These soon hatch and the nymphs in the course of a few days de- 

 velop into wingless adults^ These are each capable of giving birth 

 to six to ten young per day. As these in turn become full grown 

 in less than a week and are ready to reproduce it is apparent that 

 no crop could long survive if such an increase were unchecked. 



Fortunately, wasp-like or hymenopterous parasites, principally 

 Aphidius tcstaceipes Cress, lady birds, principally Hippodamia conver- 

 gens Guerin., lace wing flies or chrysopas and predaceous flies 

 known as syrphus flies, are very effective as a rule in preventing 

 undue multiplication. Before the death of the parasitized aphis 

 occurs the body of the insect turns light brown in color and becomes 



