398 AN ECONOMIC ENTOMOLOGY. 



strikes them with such horror that they abandon not only their 

 nest but the house itself. I have myself used this method on 

 two occasions, and have recommended it frequently to others ; 

 in every case with the best results. 



To this family belong the so-called "agricultural ants" of 

 Texas and tlie Southwest, some species also occurring in Florida 

 and other |)arts of the Southern United States. These build im- 

 mense underground nests, and keep on the surface a cleared 

 space varying in diameter according to the size of the colony. 

 They cultivate grasses on these plots, of the seeds of which they 

 are especially ft)nd, and which they store in their galleries. Their 

 food, in fact, consists mainly of seeds of various descriptions, 

 and these they gather from whatever {)lants there may be in the 

 vicinity. The insects are very abundant in some localities and 

 are great nuisances in cultivated fields, not so much from what 

 they actually destroy by eating, but from the fact that they tol- 

 erate nothing in their vicinity excei)t what suits them. They 

 have no particular use for corn or cotton, and ruthlessly cut 

 down every stalk that encroaches on their domain. The only 

 substance that has been employed against them with any degree 

 of success is bisulphide of carbon, and this should be used in 

 quantities depending upon the size of the nest. In these cases 

 the vapor should be exploded in order to produce the best re- 

 sults. The nests extend for so long a distance underground that 

 the insects will not be reached otherwise, and when the material 

 has entirely evaporated, the galleries are again useful to them. 

 On the other hand, the explosion shatters the entire nest, and 

 the insects that escape in remote galleries are not likely to start 

 again on the same soil, unless the queen also has escaped. It 

 has been already indicated that such a nest is a complicated or- 

 ganization. It contains not only its owners with all their races 

 and castes, but frequently also slaves, — other species of ants that 

 have been conquered and stolen while in the larval or pupal 

 state, and which now perform all or a great portion of the manual 

 labor of the colonies. It often contains also not only plant-lice, 

 but coccids, which are cared for in the same way, and occasion- 

 ally other species of Homoptera, such as tree-hoppers. We 

 find, in addition, numerous species of insects that seem to take 

 the part of guests. Some of these are scavengers, and they evi- 



