OUTLINES OF ENTOMOLOGY. 



39 



and from the familiarity with which they enter our rooms, especially in 

 the autumn when the colonies are disbanding, scarcely any one can fail 

 to have more or less knowledge of their appearance and habits. 



[Fig. 16.] The few solitary species belonging 



to the group of "Double-wings" 

 differ more in habit than in struc- 

 ture from the social species. No 

 so-called "neuters" or workers 

 exist among them. Each mother 

 wasp builds her own series of 

 cells, stores each with the requi- 

 site amount of food, carefully 

 yel " places her egg on the side of the 

 cell, seals it up and leaves the larva to develop without any material 

 supervision or care. 



Among the most interesting of these is a small species, of a black 

 color, banded and ornamented with pale yellow, which has a great par- 

 tiality for building its mud cells (for these solitary species do not make 

 paper, but are all masons) in key-holes and crevices indoors. On one 

 occasion which came under my observation, one of these wasps took 

 possession of some spools of thread standing on the sill of an open 

 window, and built her cells in the spindle holes, as figured above. As 

 fast as one spool was filled another was supplied, and in the course of 

 three days nine spools, averaging three cells to a spool, had been com- 

 pleted. The food stored consisted of various small caterpillars, includ- 

 ing several larvae of the Codling moth, which had been stung with suf- 

 ficient severity to produce paralysis but not death. 



The cells were scarcely more than half an inch in depth, but into 

 this small space six or seven or more larvae would be crowded, packed 

 with a deftness that was impossible of imitation by human fingers. The 

 wasp larvae developed rapidly, the young wasps appearing in less than 

 two weeks. 



The Digging wasps (tribe FOSSORES) contain the largest and most 

 beautiful insects in the Order. (See Fig. 15.) Most of the species are 

 easily distinguished from the True wasps by their spiny legs, their 

 oval or roundish eyes, and especially by the wings not being folded in 

 repose. All the species are solitary in their habits, and as a matter of 

 course only males and perfect females are developed. A few of the 

 species bore holes in dry or decayed wood, or excavate the stems of 

 pithy plants, in which to construct their cells, while others, like the 

 Mud-dauber (Pelopwus), build a cluster of pipe-like cells plastered 

 against a beam in some shed or out-building. The great majority, how- 



