HYMENOPTERA 



367 



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 temperate regions the colonies exist for only one season; the 

 males and the workers die in the autumn; the females hibernate and 

 each starts a new colony in the spring. At first the female 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 de- 

 veloped; after they appear they carry on the labors of the colony, ex- 

 panding the nest and procuring the food for the larvas; the only function 

 of the queen then is to produce the eggs. In the later part of the season 

 males and females are developed. 



The social wasps are predacious, and they feed their larva? upon in- 

 sects which they have malaxated. The wasps are also fond of the sweets 

 of flowers, the juices of fruits, and of honey-dew. 



In the temperate regions the multiplication of colonies is brought 

 about by the production of many males and females in the nest in the 

 later part of the season; these pair, the females hibernate, and each 

 female founds a new colony in the spring. But in the Tropics certain 

 species form large perennial colonies, which from time to time give off 

 swarms, in a way quite similar to the well-known swarming of the honey- 

 bee. 



The Social Polistes. — The wasps 

 of the genus Polistes and their nests 

 are very familiar objects. The nests 

 consist each of a single horizontal 

 comb suspended by a peduncle, and 

 the comb is not enclosed in an enve- 

 lope (Fig. 612). These nests are often 

 built under the eaves of buildings, in 

 garrets, and in shedsand barns; they are FlG - 612. — Nest of Polistes. 



also often made under flat stones infields, and sometimes attached to bushes. 



. The nests are made of a grayish paper-like 

 material, composed of fibers of weather- worn 

 wood, which the wasps collect from the sides 

 of unpainted buildings, fences, and other 

 places, and convert into a paste by the action 

 of the jaws and the addition of some fluid, 

 probably an oral secretion. The nests of 

 Polistes are usually comparatively small ; but 

 some have been found in Texas that measured 

 more than a foot in diameter. 

 In this genus the abdomen 

 is long and spindle-shaped (Fig. 613). 



Several of the species are known to store small quan- 

 tities of honey in their combs. 



These wasps are often infested by stylopids. 

 The Social Hornets and Yellow-jackets. — This subfamily 

 includes those wasps that are commonly known as hornets . 

 and the yellow-jackets. With these insects the body is 

 comparatively short and rather stout (Fig. 614); the abdomen is at- 



Fig. 613. — Polistes. 



