34 WEEVIL-RESISTING ADAPTATIONS OF COTTON. 



may well be questioned whether these inner bractlets have remained 

 unusiiallv hiree in the Kekchi cotton because they have a definite 

 function or because of the greater size and activity of the adjacent 

 nectaries. 



A variety of cotton called Pachon. planted rather extensively in the 

 Retalhuleu district of western Guatemala, and likewise protected by 

 the keleps, is similar to the Kekchi cotton in many respects, including 

 the possession of these large stipular bracts subtending the inner 

 iiectaries, but with the addition that the bracts are fringed with long 

 hairs, as though to hold the nectar the better. This may also be the 

 function of the hairs which cover the nectaries of the Old World 

 cottons 



EFFICIENCY OF THE KELEP PROTECTION. 



The special development of the extrafloral nectaries in the Kekchi 

 cotton has been noted in former reports, it being the nectaries which 

 attract the keleps to the cotton plant. That the kelep preys upon boll 

 weevils and protects the cotton crop was learned last year, but it was 

 still possible to question the practical value of this form of defense. 

 Such doubts would not have survived an inspection of our recent 

 experiments in Guatemala. A small field of cotton just outside the 

 kelep area was attacked by the weevils in such numbers that not a 

 single normal boll developed on any of the United States Upland and 

 Sea Island varieties. In the field protected by the keleps the weevils 

 obtained no footing until the plants were well grown and an excellent 

 crop of full-sized bolls had been developed. 



To test the efficiency of the keleps as destroyers of boll weevils and 

 as protectors of cotton would be possible in Texas only by stocking a 

 large area with keleps — a difficult and expensive undertaking. No 

 small tract would give a fair indication, since the weevils from the 

 whole neighborhood would continue to come in, and, although they 

 might soon be captured, would be able to do vastly more damage than 

 would be possible if the whole region were stocked with keleps. 



In Guatemala, however, it was quite possible to contrast a protected 

 with an unprotected piece of cotton by the simple expedient of plant- 

 ing outside the area occupied by the keleps. A more striking result 

 could hardly be imagined. For several weeks, during which the two 

 plots were under continuous obserA'ation, the one remained almost 

 entirely free from weevils and weevil injuries and set an excellent 

 crop, while in the other scarcely a floAver opened or a boll developed. 

 The ver}' few exceptions Avere on the concealed drooping branches of 

 the natiAe Kekchi cotton. 



The weevils became, indeed, too numerous for their OAvn prosperity 

 and fed upon and destroyed the very young buds before -they Avere 

 old enough to breed lar\'a?. TAventy-five fallen squares collected and 



