946 AN INTRODUCTION TO ENTOMOLOGY 



first, as a household pest, entering and overrunning dwelhngs; and 

 second, as an orchard pest. Its injuries in orchards are due to the 

 fact that it protects aphids and coccids in order to secure the honey- 

 dew that they excrete. The ants drive away the insect enemies of 

 the aphids and coccids, which as a result multiply to an abnormal 

 extent. It has been found that this ant can be exterminated in 

 houses and orchards by the use of an arsenical poisoned syrup. 

 Detailed directions for the preparation and use of this syrup are given 

 in bulletins published by the U. S. Department of Agriculture. 



Subfamily FORMICINiE 



The Typical Ants 



This subfamily is characterized by the form of the anal orifice, 

 which is rotnid, terminal, and surrounded by a fringe of hairs. The 



pedicel of the abdomen consists 

 of a single segment and there is 

 no constriction between the first 

 and second segments of the gaster 

 (Fig. 1 1 80). The following are 

 some of our more common species. 

 The carpenter ant, Campo- 

 notus herculeanus pennsylvdnicus. 

 Fig. 1 180.— A formicid ant. —This is one of the largest of our 



common ants. It is the large 

 black species that builds its nests in the timbers of buildings, in logs 

 and in the trunks of trees. Frequently it builds in the dead interior 

 of a living tree, excavating a complicated series of chambers. 



The mound-building ant, Formica exsectoides.- — This species is the 

 builder of our largest ant-hills; these are often one meter in height 

 and two meters across, and sometimes they are much larger than this. 

 New colonies are often formed by fission, a portion of the colony 

 emigrating and founding a new colony with one or more queens. In 

 this way many colonies are often established in a limited area. The 

 head and thorax of this ant are rust-red, while the legs and abdomen 

 are blackish brown. 



The blood-red slave-maker, Formica sangtmiea. — More than a 

 century ago Pierre Huber called attention to the fact that this species 

 which is common in both Europe and America, keeps in its nests 

 the workers of other species of Formica, which aid in performing the 

 labors of the colony. The relations of the two species thus associated 

 have been commonly regarded as that of slaveholders and slaves. 

 The slaveholders obtain their slaves by making periodical forays on 

 the colonies of the common black Formica fusca, and of other species 

 of Formica, and bringing to their own nest the worker larvas and 

 pupas. Some of these are eaten, but others are reared, and these 

 knowing no other home take their place as active members of the 

 colony. 



