68 THE SOLITARY WASPS. 



Bembecids cannot strictly be called solitary, and yet the extent 

 of their cooperation seems to be limited to the act of driving 

 intruders away from their nesting-grounds. Beyond this they 

 have no common cares nor duties. 



As to their relation to the larva, however, there seems to be 

 nothing transitional. Compared with the solitary wasps they 

 are at a great disadvantage, both as regards the burden of feed- 

 ing the young and the consequent low rate of increase, and in 

 their constant expocure to the attacks of parasites; and they are 

 very evidently in a less developed stage than the social wasps, 

 where all the workers join together in the labor of feeding the 

 young. 



It may be possible, then, that all wasps originally fed their 

 larvse from day to day as Betiibex now does, and that while the 

 instinct of paralyzing the prey and of storing the whole supply 

 of food once for all was working itself out among the solitary 

 wasps, the instincts connected with life in a true society, and of 

 joining together in the work of feeding the larvse, have, on the 

 other hand, developed into those of our wasp communities. 



If we look at the matter from this point of view we find 

 among the AmmopJiilae an instance which looks like a connect- 

 ing link between the habits of Benibex and those of the solitary- 

 species. A. iirnaria stores one caterpillar, lays an egg on it, 

 catches another and stores it as soon as she can and then closes 

 the nest. As a usual thing, no doubt, the nest is finally closed 

 before the egg is hatched, so that she never sees her larva. In 

 one of our instances, however, the capture of the second cater- 

 pillar was so much delayed that when it was brought in the 

 mother-wasp found a larva of a day old feasting on the one al- 

 ready provided.* 



We opened a number of the nests of spinolae but only suc- 

 ceeded in raising one of the larvae. Our notes on the subject 

 are as follows: 



*Something like this was suggested by Prof. Duncan in 1872 (See 

 Romanes', "Mental Evolution in Animals," p. 191). 



