3 66 



THE STUDY OF IXSECTS 



the adult is petiolate. These wasps provision their nests with caterpillars 

 and frequently with cankerworms. 



Fig. 6oq. — Eumenes fralernus and its nests. 



Ml 



M 



Fabre, who studied the habits of a European 



species of Eumenes observed what goes on within 



the nest by making a window in the side of it. The 



egg is suspended from the ceiling of the nest by a 



slender thread; 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 de- 

 scends to the mass of food. 



Monobia quadridens . — This species (Fig. 610) is 



common in most of the states east of the Mississippi. 



It is larger than the jug-builders, and the abdomen of 



the adult is sessile. Figure 61 1 represents a nest of this 



species, now in the Cornell University collection, which 



was made in a board in the side of a barn. The par- 

 titions are made of mud. 

 Each cell contained a pupa 

 when the nest was opened, 

 hence it was not evident 

 what the food of the larva? 

 had been; but several ob- 

 servers 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 was 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. 



Fig. 6io. — Monobia quadridens. 



Fig. 6ii. — Nest of 

 Monobia quadridens. 



THE SOCIAL VESPID WASPS 



Since these are the only wasps that are social they are commonly 

 referred to as the social wasps instead of by the more technical name. 



