SOCIAL INsEers. A great many insects lead solitary lives. Others, either as larva- or as adults, are gregarious. and in gregarious feeding and gregarious life we have the beginning of social communities. :Many lepidopterous or eaterpillars, feed together in great masses, like the army worm (q.v.) of the United States, and more especially the larva of certain silk-spinning moths, like the European processionary moth (Cncthocumpa processionca), and less marked ly the American tent caterpillar and fall web•orm (qq.v.). These tents or webs for community feeding arc carried to a higher de gl ce of perfection in the European tincine moths of the genus Hyponomeuta, and still more perfectly in the community nests of a tropical butterfly (Encheira sociulis). A number of moths make communal cocoons, but nearly all of these are tropical. The beginning of a true communal life is seen with the ambrosia beetles (q.v.) of the family Scolytithe. These are beetles which make galleries under the bark of trees, apparently cultivating a fungus which they use as food, preparing a bed for its cultivation; they also carefully remove excrement from the fungus gardens and practically bury their dead. The most perfect, socialism, however, occurs among the bees, wasps, and ants of the order Hymenop tera, and among the termites or so-called 'white ants' of the order Isoptera. Not all bees are social. A large group is composed of solitary bees. Among the social bees a more or less primi tive social life is found with the bumblebees. Here there is a communal existence. Nests are made, cells are constructed for the young, the young are fed by the adults, and there is a sepa ration into three castes, viz. females, males, and drones. There is also the beginning of a separa tion of the drones into two castes, the larger ones in general attending to the mending of the cover ing of the nests and to the ripening of the honey, while the smaller ones for the most part do the inside housework, such as the wax-repairing and the nursing of the young. The community life of the hive or honey bee is much more compli cated than that of the bumblebee, hut the work ers seem to be more uniform in their duties. The stingless tropical bees of the genera Trigona and :11elipona form very large communities. some of
them even exceeding in size those of the honey bee, hut the social life is practically the same. See BEE.
The wasps are also both social and solitary. The social species belong for the most part to the genera Vespa and Polistes. Their communities are much like those of the social bees. They are, however, not so perfect and not so persistent as those of the true honey-bee or the ants. but re semble more nearly those of the bumblebee. The comniunities of the bumblebees and the wasps are annual. Those of the honey-bee and the ants, as well as of the termites, last for a number of years. Among the wasps is a form known as worker, just as with the social bees, and the workers here, as in the other cases, are undevel oped females. Here also, as with the social bees. these undeveloped females or workers may lay eggs which invariably produce males or drones. Most of the social wasps make paper cells and nests, using for this purpose a wood-pulp com posed of fragments of wood moistened with saliva. and macerated in the mouth. The eermomy of the social wasps is not perfectly understood, doubtless owing to the difficulty of studying them, due to the irritability of the insects and to their poisonous stinging. The size of the communities varies at the season when they are largest. from a few individuals to many hundreds, as ninny as 1200 cells being found in a single nest. On the approach of winter the males and workers perish and the fertile females crawl into such protected situations as crevices of walls and in the bark of trees, and there pass the winter in the dor mant state. At the opening of npring each sur viving female founds a new colony. At first she performs the duties of both queen and worker. A small nest is made, eggs are laid in it. and when the lame hatch they are fed and cared for by the queen until they arc mature. This first generation is composed entirely of worker.. They relieve the queen of the duties which belong to them, and from this time forth her only duty is to lay eggs. The workers arc engaged in the enlargement of the nest, in the construction of new cells, and in the care of the young.