133 



MECHANICAL DESTBTTCTION. 



Various types of machines for collecting cotton boll weevils from 

 plants have been devised during the past few years. Some of these 

 have been tried for collectings the cotton bollworm (see PI. XXIV, 

 fig. 2). In one case it was determined by a series of counts that about 

 10 per cent of the bollworms were collected b}^ the machine in passing 

 over the plants. It is considered possible that machines of this char- 

 acter ma}^ be so perfected as to render their use profitable in collecting 

 bollworms. 



METHODS OF BOLLWORM CONTROL ON CORN, TOMATOES, AND 



TOBACCO. 



It must be acknowledged that thus far no satisfactory method of 

 controlling the bollworm on sweet and field corn has been discovered. 

 In those States where the insects hibernate in corn fields fall or winter 

 plowing would be especially valuable in destroying the pupse in the 

 soil. Indeed, this practice is about all that may be recommended. 

 During the present investigation tests have been made of several plans 

 which have been recommended as of possible value. The plan to 

 crush larvae in the roasting ears, by hand or otherwise, does not, 

 apparently, take account of the often numerous smaller larvas to be 

 found in the ear and which largely escape the effects of pressure fatal 

 to the larger individuals. 



Tests by Messrs. Bishopp and Jones of various substances placed 

 on corn silks and ears, as black pepper, tar, sulphur, tobacco, crude 

 petroleum, pennyroyal, creolin, pyrethrum, etc., as repellents to the 

 moth in egg laying on these parts, gave negative results. While 

 some substances apparently prevented the moths from ovipositing, 

 their effect was to kill the portions. treated. 



The first brood of larvae infesting ''buds" of corn in the spring 

 could in many instances be profitably sought for and destroyed by 

 children, or plow hands in the course of their work, thus greatly 

 lessening the numbers of the insects in succeeding generations. This 

 practice uniformly followed by the farmers of a neighborhood should 

 serve in the course of a year to so reduce the numbers of the bollworm 

 that its injuries would be of little importance. Such a plan would be 

 perfectly practicable in lessening injury to cotton, and its value would 

 be in proportion to the extent of its adoption by the planters of a 

 neighborhood. 



No experiments in the control of the bollworm on tomatoes were 

 undertaken during the present investigation. While there are but 

 few data as to the deposition of eggs by the bollworm on tomato 

 plants, it is certain that these are placed quite as promiscuously over 

 the leaves, stems, etc. , as was found to be true in the case of cotton 



