12 



BULLETIN 723, U. S. DEPARTMENT OF AGRICULTURE. 



The eggs are laid singly or in small groups on the green bolls or 

 in the flowers. Generally the eggs are to be found near the points of 

 the green bolls in the sutures marking the locks. As many as 4 

 eggs may be found in this situation and altogether as many as 20 

 eggs have been found on a single boll. It is estimated that a female 

 will deposit in the neighborhood of 100 eggs. These hatch in from 

 4 to 12 days. 



The larva, immediately on hatching, bores its way into the boll. 

 The infested bolls sometimes become recognizable by a reddish or 

 blackened discoloration which follows attack. Mr. Busck finds, 



however, that the only conclusive ex- 

 terior evidence of infestation is tlie 

 eggshell at the entrance hole or the 

 larva itself within the boll. 



The food of the larva is the seed 

 within the boll. It devours one and 

 generally proceeds to the next above. 

 Ordinarily a single larva does not 

 make its way outside of the lock 

 which it first invades, but occasion- 

 ally the adjoining lock may be en- 

 tered. It is to be noted that the 

 larva restricts itself to the interior 

 of the boll and never makes its way 

 to the outside for the purpose of 

 reaching another boll. When the 

 larva reaches full growth it often 

 protects itself by webbing two seeds 

 together, the attachment being made 

 to openings brought into contact by 

 the insect. These " double seeds " are characteristic of the work of 

 the insect. Usually they are not destroyed in the process of ginning, 

 and they furnish the best means of determining quickly whether any 

 lot of seeds is infested. 



During the summer the larva stage occupies from 20 to 30 days. 

 Later in the season this stage may be more or less indefinitely pro- 

 longed. Gough (G), in Egypt, found that larvae would remain in a 

 quiescent condition for over two years. Mr. Busck caused infested 

 seeds to be placed in small bales of cotton in Honolulu. Examina- 

 tions made up to 18 months after the time of baling continued to 

 reveal the presence of live larvae. It is thus evident that the larva 

 stage may be prolonged over at least two growing seasons. It is this 

 feature in the life history of the pest which has facilitated its car- 

 riage to many remote quarters of the earth. 



^iG. 9. — Pink bollworm on carpel of 

 cotton boll, which shows also typical 

 hole made by worm while travel- 

 ing from one lock to the next. 



