THE HYMENOPTERA 



359 



paper pulp and then molded into the desired form. In these cells she 



now places eggs and the young which hatch are fed upon insects partly 



chewed up, with perhaps the addition of some pollen. The young feed 



upon this until full-grown, then pupate in their cells. The adults which 



emerge are workers and they now begin to 



construct additional cells all in the same 



layer; feed the young and do the other work 



of the colony. Later in the season males and 



females are also produced and mate. Late 



fall stops further growth of the colony and all 



but the females die. 



Other insects of this family (Vespula, Fig. 

 380) use wood partially decayed, with which 

 to construct their nests, and an outside wrap- 

 ping is added. Here one layer of cells will not accommodate the colony 

 and several layers or tiers of cells surrounded by these wrappings are pro- 

 duced, leaving only one or two exit openings. Sometimes these nests are 

 placed in holes in the ground and the wasps locating in such places are 



FIG. 380. Social Wasp 



FIG. 381. Nest of a Hornet (Vespula maculata Kirby.), about one-eighth natural size. 



(Original.) 



often called " yellow-jackets." Other species construct their nests in 

 trees or bushes (Fig. 381), attaching them to a branch or branches. 

 There are several outside wrappings of gray papery wood pulp surround- 

 ing the tiers of cells within, of which there may be three or four, and the 

 exit opening is usually at or near the bottom of the nest. Insects making 

 nests of this kind in trees or under eaves, gable-ends of buildings or 



