The Bollworm or Corn Earworm. 13 



In rather extensive experiments an average return of $5.21 per 

 acre over the cost of poison and expense of application resulted. 

 Some of the fields were treated once and others received two appli- 

 cations. 



In sections where poisoning for the boll weevil ^ is practiced, ordi- 

 narily a high degree of control of the bollworm should result. In 

 sections where the boll weevil and bollworm are both frequently 

 bad an attempt should be made to follow the infestations in the fields 

 closely enough to make applications of the poison at the proper time 

 to check the ravages of both of these pests. 



On account of the sporadic occurrence of bollworms in great num- 

 bers in most regions it is rather difficult to foresee just when serious 

 injury is to occur, but it would no doubt be profitable to apply 

 poison each year in the portions of Texas and Oklahoma where boll- 

 worm damage is general and more severe. 



CORN AS A TRAP CROP TO PROTECT COTTON. 



Since the bollworm prefers corn to cotton or most other plants for 

 food it is possible to concentrate the larv£e on corn and keep them 

 from becoming so numerous on cotton. To effect such a result it is 

 important that corn be planted at such a time as to be in silk and 

 tassel about the 1st of August. If it matures too early it will act 

 only as a breeding place for bollworms, which will mature as the ears 

 harden and a short time later transform to moths which in turn will 

 deposit eggs over adjacent cotton fields. On the other hand, if the 

 plants are in an attractive state, the moths, which fly quite freely, 

 will assemble in the corn from considerable distances and deposit 

 most of their eggs on the corn plants. These eggs will hatch and 

 the young larvae, being so numerous, will destroy one another to 

 such an extent that usually not more than a few out of the many 

 hatching on the silk of each ear will reach maturity. 



One plan of planting the trap rows consists of leaving belts from 

 10 to 40 feet wide across the field at the time the cotton is planted 

 and about June 1 planting this space with Mexican June corn in rows 

 5 or 6 feet apart. About 10 days later a row of cowpeas may be 

 planted between the corn rows, thus leaving room for cultivation 

 and at the same time furnishing attractive places for the bollworm 

 moths, which will concentrate in the trap rows in great numbers. 

 While any variety of corn may be used, the Mexican June corn is 

 more desirable in the Southwest on account of its resistance to 

 drought. 



' The poisoning of tbe boll weevil is discussed in Bullettn 875 and Doiwirtment Circular 

 102 of the United States Department of Agriculture and in Farmers' Bulletin 1262. 



