70 .NATURAL CONTROL OF TliK COTTON BOLL WEEVIL. 



In examination of about 11,000 fallen forms collected between 

 Auf^ist 10 and Au[];ust 31, 1905, 25 per cent were squares and 75 ])eiv 

 cent were small bolls. The proportion between these forms varies 

 greatly with the stage of gi'owth in each field. In the examination 

 of 62,593 fallen forms collected l)etween June 15 and October 15, 

 1906, 64 per cent were sciuares and 36 per cent bolls. Among 24,36.) 

 hanging forms examined in 1906, 28.6 per cent were squares and 71.4 

 per cent bolls. 



In a test of the effect of hand picking of infested fallen forms in 

 1905, it is probable that between 34,000 and 42,500 adult weevils 

 were thereby prevented from emerging upon an area of 8 acres. In 

 spite of this large destruction of weevils, the increased yield of seed 

 cotton upon the test area averaged only about 50 pounds per acre 

 as compared with a check area of similar size. This shows the tre- 

 mendous importance and effectiveness of natural control, which 

 frequently produces much greater increases in yield than 50 pounds 

 of seed cotton per acre. 



In the examination of 11,000 forms from Louisiana in 1906, only 

 44 per cent were found to contain a weevil stage. The balance of 

 56 per cent included many which had been injured by feeding of the 

 weevils. Among the bolls 30 per cent and among squares 60 per 

 cent contained some stage of a weevil. Probably few of the 

 remainder of the squares had escaped some form of weevil attack, 

 but a large proportion of the 70 per cent of bolls perished without 

 any injurv by the boll weevil. 



In examinations of forms collected in Texas in 1906 among more 

 than 14,000 dried, hanging bolls, hardly 25 per cent showed any 

 stage of the weevil; among over 20,000 fallen bolls only IS per cent 

 had any stage; among 5,600 hanging dried squares nearly 60 per 

 cent and among more than 36,000 fallen squares slightly over 60 

 per cent contained a weevil stage. Practically two-thirds of all 

 weevil stages found in Texas were in the fallen squares. 



The proportion among 100 weevil stages starting in each one of the 

 four classes of forms which may be reasonably expected to reach 

 maturity and emerge is as follows: Hanging dried bolls, 55; fallen 

 bolls, 50; hanging dried squares, 20; fallen squares, 10. 



Evidently we are indebted in a very large degree to the effectiveness 

 of natural control for the possibility of continuing cotton production. 

 Such cultural methods should be followed as shall exert the strongest 

 influence upon hastening the maturity and increasing the yield of 

 the crop. In addition to this, such cultural methods should be 

 followed as will promote the highest efficiency of the factors in this 

 natural control of the Mexican cotton boll weevil. 



