68 THE SOLITARY WASPS. 



Bembecids cannot strictlj be called solitary, and yet tlie extent 

 of their cooperation seems to be limited to tlie act of dri^dng 

 intruders away from their nesting-grounds. Beyond this tbey 

 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 exposure 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 Bemhex now does, and that while the 

 instinct of paralyzing the prey and of storing the whole supply 

 of food once for all w^as 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 Ave look at the matter from this point of view we find 

 among the Ammophilae an instance which looks like a connect- 

 ing link between the habits of Bemhex 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 pro\dded.* 



We opened a number of the nests of sp'uiolac but only suc- 

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

 are as follows: 



^Something like this Avas sug-gested by Prof. Duncan in 1S72 (See 

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



