NESTS AND NEST BUILDING. In their nest building ants differ from all other social hymen optera. The nests or combs of bees are divided into even compartments or cells, whose walls are made of wax, while those of social wasps are built of a papery pulp, derived from masticated weather-worn wood. In each cell one egg is laid and one individual is reared. The young of ants, on the other hand, are kept in heaps and moved about from one part of the nest to the other as conditions of temperature and moisture demand.
The nests are eomposed of a variable number of ehambers, of irregular shape, connected by gal leries. They are excavated in the ground, often under the shelter of a stone, or in rotting or liv ing trees, shrubs or herbs. Those chambers and galleries excavated in the earth extend a eonsid erable distance down to the region of constant moisture. Some of the satiba or saliva ants of
South America can cross wide rivers by tunneling under the river-beds. Not infrequently the nests are carried above the level of the ground by means of earth heaped up and often cemented to gether. Some ant-hills are, thatched by bits of herbage. In South America ant-hills often ex ceed the height of man. Some ants tunnel out homes in the trunks of trees, others burrow in the thorns or petioles of leaves. Certain ants make homes by bending leaves in circles. The adult ants cannot produce cement, so the larvae nearly ready for the cocoon stage are utilized. Some of the workers hold the bent edges of the leaves in place, while others bring up the hi rya', whose heads they dab back and forth over the edges of the leaves so as to bind them together with silk.