ARTICULATA. 175 



similarly before they have attained their perfect state. Sometimes Aphides 

 are kept prisoners by the ants ; and we have observed a nnmber of one of 

 the species which infests the roots of grass, in their natural position upon 

 th^ roots beneath a stone occupied as an ants' nest. 



In the genus Polyergus the mouth is not adapted for building; and as the 

 economy of the nest must be carried on, they make predatory excursions to 

 the nests of two otlier species of ant, and take their young workers in the 

 pupa state. These assume their perfect state in the domicile of their captors, 

 and become the slaves of their community, all the labor of building, col- 

 lecting food, and taking care of the young, falling to them. 



St. Fargeau thinks that Polyergus exhibits the "perfection of instinct," 

 being capable of laboring, but preferring idleness ; but Iluber asserts that 

 they have no talent except that of war, and on placing S(Mne of them in a 

 glass with their pup?e, they began to die from want, until an individual of 

 Formica fK sen was introduced, which preserved the remainder. In Europe, 

 .a true working Formica makes slaves of two other species, although it 

 assists in the work ; and in the United States the large yellow ant makes 

 slaves of the black ones, both being true Forin'icce^ and both working. (See 

 Westwood's Introduction, ii. 232.) 



The habits of the driver ants of West Africa (which are the neuters of 

 the genus Dorylus) are carefully detailed in the Proceed. Acad. Nat. Sci., 

 iv. 196. They are very fierce, have no permanent abode, and live tem[K> 

 rarily in crevices. They travel at night or in cloudy weather, and if 

 overtaken by the sun they protect themselves by an arch of earth made 

 adhesive by a fluid from the mouth. Without this they would die, the direct 

 rays of the sun killing them in two minutes. It being necessary to protect 

 the young in migrating, an arch is made of the bodies of the soldiers, which 

 interlock their jaws and feet for the purpose of forming it. They move in 

 great armies, and when they enter a honse, rats, lizards, etc., and even 

 man, take their departure. They destroy large serpents, and domestic 

 animals confined in stables. Dogs and asses are afraid to leap over their 

 line when on a march. 



Fam. 16. EumenidiB. In this family the sexes appear in their ordinary 

 condition, and the species do not live in society. They resemble wasps, and 

 construct mud cells in which the egg is placed with insects, larva?, or 

 spiders, the aperture being then closed, 



Fam. 17. Yespidm {2)1. 79, figs. 20-22). This includes the wasps, which, 

 in some points of their economy approach the bees, and like these, there are 

 males, females, and workers. Many of the species are black or dark 

 colored, varied with white and yellow. They are widely distributed, espe- 

 cially in warm regions, and they live in societies during the summer, 

 building nests of hexagonal cells, made of a paper-like material, and often 

 inclosed in a globular covering of the same material, as in the case of the 

 horjiets. They feed upon insects, fruit, honey, and other materials ; and the 

 large American hornet, Ves_pa maculata., often comes about houses to catch 

 flies. The larvae are fed by the adults, and when they are ready to assume 

 the pupa state they inclose themselves by spinning a convex cap over the 



379 



