216 ELEMENTARY ZOOLOGY 



her own young". The nest is usually a short vertical or 

 inclined burrow in the ground, with the bottom enlarged 

 to form a cell or chamber. In this chamber a single egg 

 is laid, and some insects or spiders, captured and so stung 

 by the wasps as to be paralyzed but not killed, are put in 

 for food. The nest is then closed up by the female, 

 and the larva hatching from the egg feeds on the enclosed 

 helpless insects until full grown, when it pupates in the cell 

 and the issuing adult gnaws and pushes its way out of the 

 ground. Each species of wasp has habits peculiar to itself, 

 making always the same kind of nest, and providing 

 always the same kind of food. Some of these wasps make 

 their nests in twigs of various plants, especially those with 

 pithy centres in the stems. For interesting accounts of 

 the habits of several digger wasps see Peckham's 4< The 

 Solitary Wasps." 



The solitary bees, of which there are similarly many 

 kinds, are like the solitary \vasps in general habit, only 

 they provision the nest with a mixture of pollen and nectar 

 got from flowers instead of with stung insects. Some- 

 times many individuals of a single species of solitary bee 

 will make their nests near together and thus form a sort 

 of community in which, however, each member has its 

 own nest and rears its own young. In the case of certain 

 small mining bees of the genus Halictus, a step farther 

 toward true communal life is taken by the common build- 

 ing and use by several females of a single vertical tunnel 

 or burrow from which each female makes an individual 

 lateral tunnel, at the end of which is a brood-chamber. 

 Perhaps half a dozen females will thus live together, each 

 independent except for the common use of the vertical 

 tunnel and exit. 



The bumblebees (J^ombus sp.) are truly communal in 

 habit. All the eggs are laid by a queen or fertile female, 

 which is the only member of the colony to live through 



