RELATIONS WITH OTHER ARTHROPODA. 69 



tion of tlie plants by the "cotton louse," Aplns gassy pii Glov., 

 throughout the entire growing season. 



Were the jaws of the Argentme ant powerful enough to pierce the 

 cotton squares so that they could remove the boll-weevil larvae, and 

 were they so inclined, they might be of substantial service in destroy- 

 ing this pest. However, repeated experiments made by the aenior 

 author proved conclusively that the ants would not do this. The 

 following experiment will serve as an illustration of those carried out: 



On July 10, 1908, three weevil-infested squares were placed on the 

 food table of an Argentine-ant colony in the insectary at Baton Rouge. 

 The workers crawled over them constantly for three hours, but made 

 no attempt to bite into them and evidently did not suspect the pres- 

 ence of food inside of them. Afterwards the weevil larvae were re- 

 moved from the squares and placed, alive and uninjured, on the food 

 table. The ants attacked them, hesitatingly at first and then with 

 avidity, and in the course of a minute one large weevil larva was 

 dragged an mch across the food table, vertically another incli, and 

 into the vestibule of the nest. Another lot of weevil-infested squares 

 was placed on a board inside the insectary where the ants had been 

 securing other food for several days. The squares were left here for 

 five hours, during which time the ants crawled over them constantly, 

 but made no effort to open them. The ends of the squares were then 

 broken off so that the ants could enter them if they chose. None 

 entered. Presently some of the weevil larvae wriggled themselves 

 completely out of the squares and they were then attacked by the ants 

 and dragged away. 



These and similar experiments lead one to the conclusion that the 

 Argentine ant will never be of material value as an enemy of the boll 

 weevil. In fact, in this respect it can not hope to approacli in effi- 

 ciency tliie common native fire ant, Solenopsis gcminata Fab. 



BENEFICIAL ASPECTS OP THE ANT's ACTIVITIES. 



In some few cases the predatory habits of the ant take on a bene- 

 ficial aspect. In the summer of 1908 Mr. R. C. Treherne was associ- 

 ated with us in the investigation of the sorghum midge (Diplosis) 

 Contarinia sorghicola Coq. In the course of his work Mr. Treherne 

 placed heads of sorghum, milo maize, etc., in cages for the purpose of 

 rearing the adult midges. In a very short time he found that the 

 Argentine ants were invading the cages and were carrying away the 

 adult midges almost as fast as they emerged. (See fig. 10, from draw- 

 ing by Mr. Treherne.) To continue the observations it was necessary 

 to isolate the cages over trays of water or oil. For the purpose of 

 more closely observing the capture of the midges by the ants, about 

 200 of the former were placed inside a large glass bell jar. The jar was 

 raised a trifle at its lower edge by the insertion of a match. In the 



