HYMENOPTERA. 66 1 



they would do well to change their spots, so that they can be 

 distinguished at a distance. 



o 



Social wasps build their nests in the ground, or attach 

 them to bushes and trees, or to the roofs or eaves of buildings. 

 The nests are made of paper composed of bits of wood con- 

 verted into a paste by the action of the jaws. Probably these 

 insects add a fluid excreted by the mouth to the fibres of 

 wood in order to make the paste, but of this we have no 

 definite knowledge. 



The species that build their nests above ground make a 

 grayish paper composed of fibres of weather-worn but not 

 decayed wood. This material is collected from stumps of 

 trees, fences, and the sides of unpainted buildings. This 

 paper is comparatively strong ; so that, in those cases where 

 the combs are enclosed in an envelope, the envelope is com, 

 posed of sheets of paper of considerable size, a single sheet 

 often completely enveloping a nest. 



But most of the species that build their nests in the 

 ground make their paper out of partially-decayed wood. 

 This paper is brownish in color and is very fragile; it would 

 not be suitable, therefore, for use in nests built in exposed 

 places. Even when the nest is built in a hole in the ground, 

 the use of this fragile material necessitates a different style 

 of architecture. The enveloping layers of the nest, instead 

 of being composed of sheets of considerable size, are made 

 up of small, overlapping, shell-like portions, each firmly 

 joined by its edges to the underlying parts. 



The social wasps are predaceous ; and they feed theii 

 young upon insects which they have masticated. These 

 wasps are also fond of sweets of flowers, the juices of fruits, 

 and of honey-dew. They collect the honey-dew from leaves 

 in the vicinity of Aphids without, so far as we know, render- 

 ing the Aphids any service in return. 



Except in California, only two genera of social wasps 

 occur in the United States. These are Polistes (Po-lis'tes) 

 and Vespa (Ves'pa). Each of these genera is represented 



