THE INSECT IVOKLJ). 405 



In the social wasps we find a step towards the organization 

 found in a beehive, sometimes well and sometimes very poorly 

 marked ; but in all cases, besides typical males and females, there 

 is a worker caste, which, as in the ants and bees, is composed of 

 sexually undeveloped females. Briefly stated, the history of 

 these wasps is about as follows : Males and females appear in 

 fall ; the females are impregnated and live through the winter in 

 such shelter as they are able to find ; in the spring, with the ap- 

 proach of warm weather and the opening of the flowers, the 

 females revive, and at once begin reproducing their kind. They 

 start a small nest of only a few cells, and lay eggs in them as soon 

 as they are well started. In a few days the larvae hatch; the 

 female increases the size of the cells and adds to them, and to her 

 other duties is now added the care of the newly hatched young, 

 which must be fed and tended daily. In three or four weeks the 

 first larvae become full-grown, and the cells are then capped by 

 the mother. In this closed cavity the change to the pupa takes 

 place, and in due time an adult appears. This adult is a worker, 

 or undeveloped female, and at once begins to help the original 

 mother in the work of attending to the brood and increasing the 

 size of the nest. Until midsummer, at least, workers only are 

 produced ; but then, when the brood of workers is sufficient to 

 relieve the stem mother of all necessity for labor, eggs are laid 

 that produce sexually complete forms, — males and females, — which 

 generally issue during the first days of September. The old 

 female now dies, and when cold weather sets in the workers 

 and males also succumb, leaving only the impregnated new 

 females to live through the inclement season. Of course there 

 are many modifications of this general life history, and some colo- 

 nies become very much larger than others. In some instances 

 the cells seem to be used over and over again, and no more are 

 manufactured than is necessary to accommodate the brood. In 

 other instances it seems as if the cells are used only once, and 

 new ones are built for each individual larva. The locality in 

 which the nests are built also varies, although the general char- 

 acter of the comb, or cell, is nearly always the same. As a home, 

 some species, like the " yellow-jackets," select a little cavity un- 

 derground ; some, like the giant Vespa crabro, a hollow tree ; 

 some a favorable spot among the branches. Others build un- 



