ARTICULATA. 175 
similarly before they have attained their perfect state. Sometimes Aphides 
are kept prisoners by the ants; and we have observed a number of one of 
the species which infests the roots of grass, in their natural position upon 
the 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 other 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 Huber asserts that 
they have no talent except that of war, and on placing some of them in a 
glass with their pupe, they began to die from want, until an individual of 
Formica fusca was introduced, which preserved the remainder. In Europe, 
a true working /ormica 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 Formice, and both working. (See 
Westwood’s Introduction, 11. 2382.) 
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 tempo- 
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 protéct 
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 house, rats, lizards, &c., 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. Humenide. 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, larvae, or 
spiders, the aperture being then closed. 
Fam. 17. Vespide (pl. 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 
hornets. They feed upon insects, fruit, honey, and other materials; and the 
large American hornet, Vespa maculata, often comes about houses to catch 
flies. The larvee 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 
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