REPRESSION. 149 



weevils by burial. It is thus clear that as a means of controlling 

 the weevil during the growing season the burial of squares is imprac- 

 ticable. There is a time, however, when the burial of the squares 

 can be carried on to excellent advantage. This is in the fall when 

 the maximum infestation has been reached. Under these conditions 

 it makes no difference to the planter whether the lateral roots of the 

 cotton plant are cut or not. The fruit already set on the plants will 

 develop in either case, and any additional fruit inevitably will be 

 destroyed by the insects. Consequently the planter may destroy 

 many of the weevils which would mature in a short time to feed, 

 multiply, and enter hibernation, to emerge and damage the crop of 

 the succeeding season. In this way deep fall cultivation is a pre- 

 liminary step that should be practiced in connection with the destruc- 

 tion of the plants. It should precede that process and should by 

 no means be depended upon to take the place of it. After the plants 

 have been uprooted and brought into windrows previous to burning 

 it is advisable to plow the fields to a depth of at least 2 inches. This 

 will result in the burial of many squares which were on the ground 

 at the time of the uprooting or which fell during the process. The 

 experiments show that the effectiveness of burial either before or 

 after the uprooting of the plants will increase greatly if rains occur 

 after the work is done. Likewise it is evident that the destruction 

 of the weevils will be much greater in heavy soils than in lighter 

 formations. In the Mississippi-Yazoo Delta the general nature of 

 the soils is more or less heavy. This and the heavy precipitation in 

 that region indicate a means of destroying the weevil that is especially 

 important on account of the scarcity of direct means available. 



INSECTICIDES. 1 



From the very beginning of the work on the boll weevil much atten- 

 tion has boon given to testing the more promising insecticides. As 

 one result of the offer of a $50,000 prize by the State of Texas for an 

 efficient remedy for the boll weevil, large numbers of supposed reme- 

 dies have been proposed. Doubtless the inventors have been per- 

 fectly sincere in their faith in the efficiency of these compounds. As 

 was fully anticipated by the entomologists when the reward was 

 offered, the commission charged with awarding the money was 

 deluged with applications therefor, the claims in a large majority of 

 cases being based upon some concoction supposed by the inventor to 

 possess marvelous insecticidal properties. In comparatively few 

 cases had the new product been tested in any way. Often samples 

 were sent with the request that tests be made. Many of these inven- 

 tions found their way to the various laboratories of this investigation, 

 where it has been the uniform policy to give every thing of this kind 

 a fair test and report the results to the originator. Tests were made 

 in the field upon weevils confined by cages. This work has required a 

 great deal of time, and the results have failed to indicate a single new 

 compound having real value. Many of the substances tried had 

 absolutely no effect on either plant or insect life, while others were 

 equally fatal to both wherever they came in contact with them. The 

 primary difficulty with all such insecticides lies in the fact that, 



1 The first two paragraphs under this heading have been modified from Bull. 51, Bureau of Ento- 

 mology, p. 156. 



