16 BULLETIN 918, U. S. DEPARTMENT OF AGRICULTURE. 



sisting of full-fed worms and the younger the winter-feeding brood, 

 which were not full-fed at the time of hibernation and continue 

 developing slowly till about March. In a later publication (12) 

 weighings of resting larvae were made from January to July and it was 

 found that the weight constantly fell from February to July. He 

 concludes that "the fall in weight does not necessarily demand the 

 explanation that the larvae were fasting, but taken along with the 

 known fact that many hibernating or aestivating larvae do not feed, it 

 lends considerable weight to the probability of the larvae not feeding 

 during their resting period." 



A very small proportion of the larvae have not completed their 

 growth when the cotton is picked, and these continue feeding for a 

 while before making their resting cocoon. In some bolls examined 

 November 26, 1918, there was an average of 6.64 fourth-instars and 

 0.03 third-instars per boll. After the resting cocoon is once spun 

 no feeding takes place. If larvae are removed from the seeds in 

 which they are resting, other seed will sometimes be hollowed out, 

 but the contents are thrown to the outside and no actual feeding 

 takes place. It sometimes happens that frost does not come in the 

 Laguna till January or February, and it is probable that feeding 

 continues longer than usual in such years. 



Duration of the Resting Stage. 



Larvae are capable of passing long periods of time in this quies- 

 cent stage. Gough (5) found in seeds of Indian cotton which had 

 been imported to Egypt larvae which were over 2 years old. Busck 

 (8) in Hawaii compressed cotton seed into small bales and found 

 live larvae in them for 18 months. Willcocks (7) stored a large 

 number of bolls picked in November, 1913, in an outdoor cage, and 

 moths continued emerging till August 28, 1915, a period of nearly 

 2 years. There were 4.4 per cent of the larvae in double seed col- 

 lected in November, 1918, still alive on November 20, 1919, when 

 work at the station was discontinued. 



Pupation of Resting Larvae. 



When the resting stage has been passed in the lint, single seed, or 

 in any place where the larva is curled up in a small, compact cocoon, 

 it is necessary to leave this cocoon and prepare more ample quarters 

 for pupation. In such cases a lighter, more elongate cocoon is usu- 

 ally spun among the fiber or seed, but in some instances in stored 

 seed pupae are formed without any protection whatever. 



When the resting stage has been passed in the double seed the con- 

 struction of the cocoon between the two seeds makes it elongate 

 enough for the larva to pupate successfully and pupation usually 

 takes place in situ. In such cases the emergence hole for the moth 



