81 



number of caterpillars was taken to the laboratory, where they could 

 be watched and the general facts of their life history determined. All 

 the larvae spun up within five days after being taken from the field. 

 The average length of the pupal stage was about two weeks, varying 

 only a few days in any case. As the moths were found to be depositing 

 eggs it was thought best to follow the life history of the following 

 generation. 



The eggs with which these studies were started were brought from 

 the field on August 21. The}' formed a compact group nearly an inch 

 across, being placed closel}' side by side upon the under surface of the 

 cotton leaf. The number of eggs deposited in a group varied, some 

 having been found numbering between 900 and 1,000. 



J . — • "s. 



Fig. 19.—Estk/mrne acrxa: a, male moth; h, lialf-grown larva; ^, mature larva, lateral view; d, head 

 of same, front view; e, egg mass— all slightly enlarged except d, more enlarged (from Chittenden) . 



EGG. 



The eggs were nearly round, about two-thirds of a millimeter in 

 diameter, and, when first deposited, of a pale yellow color. The surface 

 of each was slightly granular in appearance. As the embryo became 

 nearly developed the color of the egg changed to a dull blue, with a 

 black spot near the middle of the top. Hatching occurred in four or 

 five days. The percentage failing to hatch was very small and no para- 

 sites were developed in this lot of eggs. 



LARVA. 



As they left the eggs the larva? were about 2.3™™ long. Their color 

 was a uniform dark brown, and the length of the hairs was nearly 

 equal to that of their l)odies. 

 22104— No. 44—04 6 



