PINK BOLLWORM OF COTTON IN MEXICO. 



9 



As the female does not deposit eggs readily in captivity, diffi- 

 culty was experienced in determining exactly how many eggs 

 were deposited by a single female. In our experiment usually 

 from 5 to 20 moths were confined in one cage. Under these con- 

 ditions it was never known which moths had oviposited and 

 which had not, and while several hundred eggs were often obtained 

 from a cage, it is certain that the maximum number they were 

 capable of laying were never obtained. Often heavy, pregnant 

 females were found dead in the cage and apparently never had 

 deposited any eggs. Upon dissection of gravid females the ovaries 

 were found to contain from 75 to 125 well-developed eggs. Busck 

 (8) places the number at over a hundred and Willcocks (7) says that 

 while small individuals may produce only about 250 eggs, well- 

 developed individuals are capable of laying 400 to 500 eggs or more. 



Figure 



too 



90 



eo 



70 

 60 

 SO 



















































































































































































«//W. FETB. MUR. APR. ItiRY JUNE JULY M6. SEPT. OCT. HOI/. 



Incubation. 



All of our records were made under laboratory conditions. 

 3 shows that the dif- 

 ference between the 

 maximum and the 

 minimum, or the day 

 and night tempera- 

 tures, for each month 

 amounts only to from 

 6° to 8° F. 



The egg stage, even 

 under these rather 

 constant conditions, 

 varied from 3 to 12 

 days. The range for 

 the months of April, 



MaV September and FlG ' 3 - — Avera § e me an maximum and average mean minimum 

 „ / ' " „ ' temperatures for 1919 at Ciudad Lerdo, Durango, Mexico. 



October was from 7 



to 12 days, and for June, July, and August it was from 3 to 5 

 days, with an average of 4.6 days for the entire season, the average 

 being taken from 300 records based on thousands of eggs. 



Hatching. 



The actual hatching of the egg requires only a very short time. 

 The young larva can be seen moving inside the shell a short time 

 before it actually emerges. An opening is cut in the broad end of 

 the egg and the small larva wriggles out and crawls rapidly away 

 in search of food. 



The empty shell is white and soon becomes an almost unrecog- 

 nizable wrinkled object. It remains on the plant until it decays or 

 is carried away by the wind or other agencies. 

 11696°-21— Bull. 918 2 



