CESSATION OF WEEVIL INJURIES DURING DROUGHT. 9 



all of the first buds, no damage was being done in the middle of July, 

 nor were there evidences of any recent injuries by weevils. A care- 

 ful search over several different plats of cotton failed to find a sin- 

 gle bud, or " square," with a normal weevil puncture. Weevil larvae 

 could still be found in very small numbers in old squares on the 

 ground under the plants, but almost invariably dead or dying. Not 

 a single adult weevil was found. The only weevils that appeared 

 likely to survive were a few small larvae in some of the earlier bolls, 

 and these would not do further injury in that season, for the larvae 

 develop very slowly in the bolls and are not likely to emerge until the 

 bolls open at maturity. 



Careful examinations of the same plats had been made by Mr. S. H. 

 Hastings, superintendent of the San Antonio farm, in May and June, 

 when an unusually heavy infestation of weevils was found. Under 

 date of June 14, Mr. Hastings reported that nearly all the buds had 

 been destroyed by the weevils as fast as they were formed and that a 

 total failure of the crop was threatened. Had the weather continued 

 favorable for the weevils there was certainly no prospect that the 

 later buds could have fared any better than their predecessors, but 

 the advent of dry weather completely changed the situation and set 

 a definite limit to the activities of the weevils. Similar cases had 

 been observed in previous years when there seemed to be a lessening 

 of weevil injuries as the season advanced instead of the increase that 

 had been feared, but no such complete interruption of injuries by 

 weevils during the growing season of the cotton had been observed. 



The effects of heat and dryness upon the weevil larvae were doubt- 

 less intensified indirectly by the influence of the drought upon the 

 plants. Injured buds are dropped much more promptly in dry 

 weather, and in severe drought even the uninjured buds may fall off, 

 thus lessening still further the weevil's opportunities of propagation. 

 The result of the earlier falling of the infested buds is to expose the 

 larvae to adverse conditions at earlier stages in their development and 

 for longer periods of time. 



The effect of the prolonged drought in completely preventing the 

 continuation of the weevil injuries was not confined in the season 

 of 1909 to the vicinity of San Antonio. The same condition of 

 unusually heavy infestation appeared early in the season in the 

 experiments conducted at Waco, Tex., by Dr. D. A. Saunders, and 

 the same complete cessation of weevil injuries was observed with the 

 advance of drought. Careful examination of several fields of cotton 

 in the vicinity of Waco on August 18 and 19 by Dr. Saunders and 

 the writer showed that no injury was being done by the weevils, 

 though the insects remained active in more luxuriant fields on rich 

 bottom lands of the same district. 

 100712°— Bull. 220—11 2 



