46 PAPERS ON THE COTTON BOLL WEEVIL, ETC. 



AN ENEMY OF THE COTTON LEAF-WORM AND BOLLWORM. 



This species has long been known as an important enem}' of the cot- 

 ton leaf -worm {ALcibmna argillacea Ilbn.), what is probably the first 

 notice of its good service in this connection having been published in 

 IS-iT. Since that time so many observers have reported it as attacking 

 the eggs, larv?e, and pupa? of the leaf- worm that there can be no doubt 

 of the substantial accuracy of the conclusion that it is one of the most 

 important predaceous enemies of that cotton pest. 



While less study has naturalh^ been given to the relationship of ants 

 to the cotton bollworm than to the leaf-worm, it has been shown 

 repeatedly that the species under consideration pre3^s upon both the 

 eggs and larv?e of the bollworm in much the same way as it does with 

 the leaf -worm. 



ITS WORK AS AN ENEMY OF THE COTTON BOLL WEEVIL. 



Considering the important place that these ants hold among the nat- 

 ural foes of the two cotton pests of most serious importance before 

 the advent of the Mexican cotton boll weevil, it is not at all surprizing 

 to find it filling a high place as an enemy of the weevil. For several 

 years it has been known that ants frequently attack the immature 

 stages of the weevil in both squares and bolls, but observations made 

 durino' the season of 1905 have shov/n that this native ant n>av be — at 

 least under favorable conditions — a more important factor in the 

 destruction of the weevil than has hitherto been supposed. 



During the experiment which was being made to test the effect of 

 direct sunshine in destro3nng immature stages of the weevil, 150 

 squares were selected, each of which was believed to contain some 

 stage of the insect. These squares Avere di^■ided into two lots of 75 

 squares each and placed upon the bare ground in an exposed spot in 

 the cotton plat at the laboratory in Dallas, Tex. One lot was left dr}^, 

 while the other was thoroly wetted to determine whether the mortality 

 would be as great in exposed squares which were kept moist. The 

 squares were placed on the ground at 4.30 p. m., September 5. The 

 following morning, while again wetting the lot which was to be kept 

 moist, numerous ants were noticed running around and over the 

 squares, tho no sign of a nest had been seen near that spot on the 

 previous evening. A hasty examination showed, in several squares, 

 holes (fig. 7, ^, (■) which in size and external appearance resembled weevil 

 emergence holes (fig. 7, a) so closely that at first they were mistaken for 

 them, and it was feared that the stages of the weevil in the squares were 

 too nearl}^ mature to serve as suitable material for the experiment 

 intended. A more careful examination, however, showed that the 

 weevils were not emerging, but that the holes in the squares were really 

 entrance holes made b}^ the ants to enable them to get at the immature 

 weevils within. As it was evident that nearly all of the squares had 

 been opened, the experiment intended was abandoned and a complete 

 examination made of all the squares. 



