INSECTS AFFECTING MAN AND ANIMALS 399 



between the walls, under the hearthstones, or in other suitable 

 places. The small black ant, M. minimum, the pavement-ant, 

 Tetramorium ccespitum, of many eastern cities, and other 

 species which have their nests out of doors, frequently invade 

 houses and cause great annoyance by getting into all kinds 

 of food. As in the field so in the houses the Argentine ant is 

 by far the most important in regions where it occurs. Indeed 

 in places where this introduced species is well established the 

 other species disappear, for the intruder attacks and finally 

 overcomes, by sheer force of numbers, all other kinds of ants. 



Nearly all ants live in large colonies in a common nest, but 

 the Argentine ants build small nests or burrows anywhere 

 throughout the infested region. Not only are the Argentine 

 ants more numerous than other 

 species, but they are more per- 

 sistent in their search for food, 

 and methods that usually afford 

 protection from other ants are 

 of little or no avail against 

 this introduced marauder. 



The best way to get rid of FIG. 185. Argentine ant, In- 

 most ants is to find the nest and fjjjjj^ humilis - (Much en ' 

 treat it with carbon bisulphide, 



pouring a few ounces of the liquid in holes made in the 

 nest and immediately stopping up the holes so the gas will be 

 forced throughout the nest. Colonies of the house ants may 

 often be treated with gasoline or boiling water. Dilute car- 

 bolic acid injected into the crevices through which the ants 

 enter a room will sometimes drive them away. Oil of lemon 

 diluted with alcohol will serve the same purpose for some 

 species. When it is impossible to destroy the nests, many 

 of the ants may be trapped by putting out scraps of attrac- 

 tive food or sponges wet with sweet syrup. The persis- 

 tent use of such traps will usually give relief from the 

 pests if the baits are removed as soon as they are covered 

 with the ants. Powdered borax spread around the thres- 

 hold or other places where the ants enter will act as a re- 

 pellent. Wood or cloth that has been treated with a 



