972 



AN INTRODUCTION TO ENTOMOLOGY 



when the larva hatches it at first makes use of the egg-shell as its 



habitation and stretches down to feed on the 



caterpillar below it; if disturbed it retreats up 



its support. Later when the larva has increased "^ '" 



in size and strength it descends to the mass of 



food. 



Monohia quddridens. — This species (Fig. 1187) 

 is common in most of the states east of the Missis- 

 sippi. It is larger than the jug-builders, and the 

 abdomen of the adult is sessile. Figure 1 1 88 repre- 

 sents a nest of this species, now in the Cornell 

 University collection, which was made in a board 

 in the side of a barn. The partitions are made of 

 mud. Each cell contained a pupa when the nest 

 was opened, hence it was not evident what the 

 food of the larvce had been ; but several observers 

 state that this species stores its nests with large 

 cutworms; and it is doubted that this species is a 

 carpenter-wasp. It seems probable that the nest 

 figured here w^as made in a deserted burrow of the 

 large carpenter-bee, Xylocopa virginica. It differs 

 from a nest of this bee only in that the partitions 

 are made of mud. 



THE SOCIAL WASPS 



Since the social Diploptera are the only wasps 

 that are social they are commonly referred to as 

 the social wasps instead of the more technical 

 name. 



As with the ants the colonies of social wasps 

 consist of three castes, the female or queen, the 

 workers, and during the later part of the season, 

 the males. The workers are females in which the 

 reproductive organs are imperfectly developed. 

 In the genus Belonogaster a worker caste is be- 

 lieved to be lacking. In Polistes it is very difficult 

 to make a distinction between females and work- 

 ers, for they can apparently all become fertile. 



In the temperate regions the colonies exist 

 for only one season; the males and the workers 

 die in the autirmn ; the females hibernate and each 

 starts a new colony in the spring. At first the fe- 

 male performs the functions of both worker and 

 queen, starting the building of the nest and laying 

 the eggs. In the early part of the season only 

 workers are developed; after they appear they 

 carry on the labors of the colony, expanding the 

 nest and procuring the food for the larv£e; the only function of the 



Fig. II.S8 — Xest of 

 Motiobia quadri- 

 dens. 



