82 



The newly hatched larva? were placed upon fresh, tender cotton leaves 

 and began at once to feed, eating- only part way through, so as to leave 

 intact the epidermis on one surface of the leaf. As a rule they chose 

 the under side, probably in part for protection and in part because of 

 the more tender tissue on that side. The length of the body during 

 the hrst larval stage increased to about 10 mm and the color became 

 yellowish brown. 



In the second stage of the larva the coloration appeared more 

 clearly. The subdorsal tubercles became black and prominent. There 

 was an interrupted white dorsal stripe and lateral stripes of a tawny 

 yellow color. The hairs were long and black. As the second molt 

 was approached the subdorsal dark stripe became lighter in color and 

 the black tubercles standing therein appeared more prominent. The 

 length of the second stage varied between four and seven days, and 

 during this time the length of the body increased to about 15 mm . 

 Feeding was almost entirely confined to one surface of the leaf 

 throughout this stage. This habit of feeding only upon one surface 

 of the leaves easily explains the failure to poison the caterpillar which 

 was at first reported. 



At the beginning of the third stage the color of the larva? appeared 

 markedly darker than in the second. The subdorsal stripes, especially, 

 were very dark, though the color was somewhat variable as it is in 

 all stages. During this instar the larva? began to consume the entire 

 leaf tissue, that is, they ate clear through instead of leaving the epi- 

 dermis upon one side. Midribs and heavy veins alone were left. The 

 length of the stage varied between six and ten days. The length of 

 the larva's body increased to more than 30 mm . 



The fourth and fifth stages showed little change in general appear- 

 ance. All the specimens bred were dark, while many found in the 

 field were much lighter, and some which seemed to belong to the same 

 species were of a bright, uniform yellow color. The length of the 

 fourth stage varied between five and nine days and the average length 

 of body became about 45 mm . The duration of the fifth stage varied 

 between eight and twelve days and the length of the body averaged 

 about 55 mm . 



The entire time of the larval stage was found to vary between the 

 extremes of twenty-four and thirty-seven days from the hatching of 

 the egg to the spinning up of the larva. The mean average tempera- 

 ture for this period was about S2.S C F., or almost -±0 C of effective 

 temperature. 



PUPA. 



Pupation took place in about two days after spinning. The cocoons 

 averaged about 30 mm in length by 10 to 12 mm in breadth. The length 

 of the pupal stage, or from the spinning of cocoon to the emergence 



