PINK BOL.LWORM OF COTTON IN MEXICO. 53 



large numbers of moths were emerging from material at the labora- 

 tory which had been taken from this same shed a few weeks before, 

 and it is certain that large numbers of moths were emerging in the 

 seed shed while the trap was in operation. Light traps have been 

 recommended as a means of control by several people. Gough {12), 

 Willcocks (7), Ballou {11), and others report catches of thousands of 

 moths per night in light traps. Ballou {11) found that most of the 

 moths came to the light in the hour following sunset. Some authors 

 found lights so attractive to the moths that they were used to deter- 

 mine the number of moths emerging from stored material, but in 

 Mexico we found that practically none came to the lights. Busck {8) 

 in Hawaii also found that the pink bollworm moths were not at- 

 tracted to lights. 



Attraction to Fruit. 



Cone-shaped traps of the type used for flies were baited with 

 oranges, bananas, apples, mangoes, guavas, and pineapples and were 

 repeatedly exposed among the cotton plants with absolutely negative 

 results. 



RECOMMENDATIONS FOR CONTROL. 



Too much can not be said and done in encouraging the destruction 

 of hibernating larvae. They are the source of infestation for the fol- 

 lowing year. If 9 per cent or less of the larvse are able to sur- 

 vive the natural mortality of winter and early spring in irrigated 

 fields, this small percentage, with the larvse surviving in the seed and 

 other places, produces an infestation the following year that causes 

 approximately 25 per cent gross loss to the Laguna crop. Every 

 hibernating larva killed during the winter or early spring before 

 oviposition begins means the cutting off of many thousand larvae by 

 the end of the season. The paramount necessity, then, is to re- 

 duce the survival of hibernating larvae to as low a figure as possible. 



Burning of Old Stalks and Bolls. 



Just as soon as possible the stalks should be cut and raked up in 

 piles. Old bolls, sticks, and trash of all descriptions to which larvae 

 may be attached should be carefully picked up and burned with the 

 the stalks, the main object being to burn everything in the field that 

 contains larvae or would be likely to afford protection for hibernating 

 larvae. If possible, the cutting and piling of the stalks should be done 

 while the plants are still green, in this way minimizing the labor and 

 increasing the effectiveness of the operation. Green stalks will 

 retain most of their bolls, which shatter when they are cut dry. Just 

 as soon as the piles lose their green color and become more or less 

 dry they should be burned. Better results can be gained by waiting 

 for this drying to take place rather than by burning the plants while 

 they are yet green. Ordinarily the old stalks are cut and burned in 



