4 THE SOLITARY WASPS. 



upon them. Before long many hundreds of neuters are busy 

 at work, no drones appearing until the summer is somewhat 

 advanced. While the warm weather lasts the nest continues to 

 increase in size and numbers, but in the first cool days of fall 

 the neuters and queens desert it, leaving the helpless drones and 

 undeveloped grubs to starve. The neuters, after leading a 

 wandering life for two or three weeks, perish with the first 

 frosts, the queens alone being left, and doubtless many of these 

 also die in the severe cold winter. 



* The solitary wasps differ from the social, in having only two 

 sexes. Each female makes a separate nest and provisions it 

 by her own labor; and in many cases a new nest is made for 

 each egg. There is no cooperation among them, although in 

 certain genera, as Pelopaeus and Bembex, a number of individu- 

 als build close together, forming a colony. The nests may be 

 made of mud and attached, for shelter, under leaves, rocks, or 

 eaves of buildings, or may be burrows hollowed out in the 

 ground, in trees or in the stems of plants. The adult wasp lives 

 upon fruit or nectar but the young grub or larva must have ani- 

 mal food, and here the parent wasp shows a rigid conservatism, 

 each species providing the sort of food that has been approved 

 by its family for generations, one taking flies, another bugs, and 

 another beetles, caterpillars, grasshoppers, crickets, locusts, spi- 

 ders, cockroaches, aphides or other creatures, as the case may be. 



The solitary wasps mate shortly after leaving the nest, in the 

 spring or summer. The males are irresponsible creatures, aiding 

 little, if at all, in the care of the family. When the egg-laying 

 time arrives the female secures her prey, which she either kills 

 or paralyzes, places it in the nest, lays the egg upon it, and then, 

 in most cases, closes the hole and takes no further interest in it, 

 going on to make new nests from day to day. In some genera 

 the female maintains a longer connection with her offspring, 

 not bringing all the provision at once but returning to feed the 

 larva as it grows, and only leaving the nest permanently when 

 the grub has spun its cocoon and become a pupa. 



The egg develops in from one to three days into a footless, 



