HYMENOPTERA 



959 



Fig. 1 194. — Early stage of nest of Vespa. 



envelope. By these additions the nest may become of large size by 

 the end of the season. 



Very small empty nests consisting of a single comb with but few 

 cells and enclosed in an envelope of only one or two layers of paper 

 are often found (Fig. 11 94). 

 Such a nest is evidence of a trag- 

 edy. A queen wasp, in the 

 spring, had started to found a 

 colony. It was necessary for her 

 to go back and forth in the fields 

 collecting material for her nest 

 and food for her larvae; and be- 

 fore a brood of workers were de- 

 veloped to relieve her of this 

 dangerous occupation she became 

 the prey of some bird and the de- 

 velopment of the colony was 

 wrecked. 



Two quite different types of 

 nests are made by different spe- 

 cies of these wasps, and these are 

 made in quite different situations. 

 One kind is built above ground; 

 these are attached to bushes or 

 trees, or beneath the eaves of 

 buildings; they are made of a 



grayish paper composed of fibers of weather-worn but not decayed 

 wood. This paper is comparatively strong, so that the envelope of 

 the nest is composed of sheets of paper of considerable size, a single 

 sheet often completely enveloping the nest. 



The other kind of nest is built in a hole in the ground, which is 

 enlarged by the wasps as they need more room for the expansion of 

 the nest. The paper of which these nests are made is brownish in 

 color and is made out of partially decayed wood; it is very fragile 

 and would not be suitable, therefore, for use in nests built in exposed 

 places. Even though the nest is built in a protected place, the use 

 of this fragile material necessitates a different style of architecture. 

 The enveloping layers of the nest, instead of being composed of sheets 

 of considerable size, are made up of small, overlapping, shell-like 

 portions, each firmly joined by its edges to the underlying parts. 



If a completed hornet's or yellow-jacket's nest be examined it 

 will be found that some of the later-built combs consist wholly or in 

 part of cells that are larger than those in the first-made combs ; the 

 smaller cells are those in which workers were developed; the larger 

 ones those in which the sexual forms were reared. 



It has been found that at least two species of this subfamily are 

 social parasites. In these species the worker caste has been lost, 

 there being only males and females. The female enters the nest of 

 another species of Vespa and lays her eggs, and her larvae are reared 



