LARGE INVOLUCRES OF KEKCHI COTTON. 39 



genera Solenopsis and Tapinoma. a There was no indication, how- 

 ever, that these afforded any protection against the weevils, although 

 they might, perhaps, act as watchmen and scare weevils away when 

 they happened to be present on buds or bolls where weevils had 

 alighted, like other small ants which have been reported as attacking 

 the boll weevil. The keleps belong in an entirely distinct category 

 in being able to sting and carry off the weevils and make regular use 

 of them as food. Instead of being of service to the cotton these 

 small ants at Rabinal were a distinct injury; the Solenopsis was 

 taking care of plant lice, 6 which often infested the cotton to a 

 decidedly harmful extent. It continues and supplements the work 

 of the boll weevils in stunting and distorting the plants. When the 

 aphids are very numerous, the leaves are badly curled and growth is 

 greatly impeded. 



LARGE INVOLUCRES OF KEKCHI COTTON. 



The Kekchi cotton has the bracts of the involucre much larger in 

 proportion to the contained bud than the Rabinal cotton or than any 

 of our Upland varieties. The possession of larger bracts constitutes 

 a distinct weevil-resisting adaptation, since it permits the involucre, 

 to be more effectively closed and the protection to be continued for a 

 longer time. Sooner or later, of course, the bracts must be separated 

 by the growing bud. The larger the bracts the longer the bud can 

 continue to grow before spreading the bracts apart. (PI. IX, fig. 1.) 



Prof. H. Pittier, who had charge of the Secanquim experiment in 

 the latter part of the season, was especially impressed with the pro- 

 tective utility of the larger bracts of the Kekchi cotton, as shown by 

 the following summary of his observations: 



The large size of the bracts in proportion to the floral bud is a very important 

 protective feature. In the Kekchi cotton the amplitude of these bracts is such 

 as to completely inclose the bud at all times before the anthesis, and even in 

 cases when they happen to be slightly separated the occlusion is maintained by 

 the long hairs which fringe them on all sides. The length of these hairs con- 

 stitutes a serious obstacle to the progress of the weevils, whose tarsi can not 

 obtain a firm hold on the solid surface. I have seen them drop to the ground 

 after many awkward attempts to gain access to the squares, while on the other 

 hand the keleps did not seem to be impeded at all by the bristles. 



« The material was not sufficient for a conclusive determination of the species. 

 Doctor Ashmead says : " You have two distinct species of ants here. One, No. 

 I, belongs to the family Myrinicidae and is apparently the worker of Solenopsis 

 picea Emery ; the other, No. 2, belongs to the family Dolichoderida? and is 

 apparently the worker of Topinoma ramulorum Emery. I am sorry you did 

 not have the different sexes, so that I could make positive of the species. In 

 Solenopsis, as you probably know, there are four or five different forms, and it 

 is not easy to identify from a single form." 



» These have been identified by Mr. Theodore Pergande as Aphis gossypii, a 

 species well known in the United States. 



