INSECTS INJURIOUS TO COTTON 



229 



Only a few of these survive, but they are very capable ancestors. In 

 early March they lay eggs upon volunteer cotton when it is only 

 an inch or two high. The eggs are laid singly, usually upon the 

 under surface of the leaves near the top of the plant, and about 

 500 are laid by each female. The egg is of a flattened convex 

 shape, bluish-green in color, and with prominent ridges converging 

 to the apex. In midsummer the eggs hatch in three or four days, 

 but in spring and autumn a much longer time is required. The 

 young larvae are a pale yellow color, but soon assume a greenish 

 tinge, and are marked with dark spots which become more dis- 

 tinct after the first moult, when they become marked like the full- 

 grown caterpillars, being 

 more or less striped with 

 black. During the early 

 season the greenish cater- 

 pillars predominate, but 

 later the black stripes 

 become heavier and the 

 darker forms prevail. 

 The appetites of these 

 caterpillars are only too 

 well known to the cotton- 

 grower. At first they are 

 content with eating only 

 the under surfaces of the 

 leaves, occasionally pierc- FIG. 193. Cotton-worm egg parasite (Pentar- 

 ing through. Then the *!*">.' ... *ult .female, greatly 



leaves commence to look 



ragged, and when they 



become scarce the tender twigs and buds are attacked. When 



they are excessively abundant the larvae develop cannibalistic 



tendencies, like the boll worms, and often feed upon the weaker 



caterpillars. The larvae become full grown in from one to three 



weeks, during which time they moult some five times. 



When mature the caterpillar crawls into a folded leaf, which is 

 often so eaten away that the pupa hangs exposed, and there 

 spins around it a thin silken cocoon and transforms to the pupa, 

 in which state the insect remains dormant for from one to four 

 weeks, when it emerges as an adult moth. 



enlarged; 6, ovipositor; c, female antenna; 

 d, male antenna. (From Fourth Kept. U. S. 

 Entom. Comm.) 



