24 NATURAL CONTROL OF THE COTTON BOLL WEEVIL. 



The native ants concerned in the control of the weevil are princi- 

 pally of the genus Solenopsis and varieties of the specie- geminata 

 (fig. 2). 



The principal points in the characterization of this species are as 

 follows: There are two distinct nodes or scales in the slender petiole 

 of the abdomen. All forms but the male have a sting (PI. II, fig. 2). 

 The antennae (PI. II, fig. 3) are ten-segmented; the club is. formed 

 of the last two segments, of which the terminal one is the longer. 

 Maxillary and labial palpi have each two segments. The clypeus 

 has two longitudinal ridges and the sting is very large. The color 

 varies, but the workers usually seen are of a dark reddish brown, 

 the color of the abdomen being often considerably darker than that 

 of the head and thorax. Length of workers from 2 to 3 mm. 



These ants form nests near the surface of the ground. All stages 

 of development and forms of adults may be found in these nests 



practically throughout the summer season. 

 The individuals which are most active, if 

 not in fact those which are alone concerned 

 in the attack upon the weevil, are the 

 smaller w orkers which are commonly to be 

 seen outside of the nests. In Plate II, 

 figures 5 and 6, are shown some of the 

 immature stages of this species. The 

 queen larvse are very much larger than 

 the worker forms as is shown in the illus- 

 tration. The pupae are naked, and as they 

 approach maturity the color gradually 

 changes from a translucent white to a dark 

 brown. The active worker form is shown 



Fig. 2.— Solenopsis geminata, ant ene- in Plate II, figures 1 and 4. 



^n^err Hinat en ' arged This species shows a tendency to nest 



within the shade formed by the plants, and 

 is to some extent out of the reach of ordinary cultivation by being 

 close to the middle of the rows. The breaking up of a nest, however, 

 does not seem to drive them away or to interfere seriously with their 

 activities. In Plate III, figure 2, are shown cotton squares which 

 have been entered by these ants and in which weevil stages have 

 been destroyed. A comparison of the external resemblance of these 

 entrance holes with the exit holes made by weevils is shown in Plate 

 III, figures 1 and 2. 



Since, in external appearance, the emergence holes made by adult 

 weevils in escaping from squares resemble very closely the entrance 

 holes made by the Solenopsis ants in obtaining access to the weevil 

 stages in a square, it seems advisable to add a brief explanation of 

 the manner in which these two classes of squares may be positively 

 separated. In all cases the final determination as to the class in 

 which a square belongs rests upon an examination of the interior. As 



