24 BEES AND WASPS [OH. 



of A.campestris, otherwise very similar, is interestingly 

 different. This latter species captures small cater- 

 pillars, of such size that two would not be an adequate 

 provision : she does not, however, complete the pro- 

 visioning at the time when she constructs the burrow, 

 but for several days returns bringing a few fresh 

 caterpillars for her growing young every morning. 

 The burrows of this species, unless they have but 

 recently been made, invariably contain several freshly 

 caught caterpillars, a few partly devoured, and the 

 empty skins of a few others : and I have repeatedly 

 observed A. campestris carry caterpillars into burrows 

 which, when opened up, were found to contain large 

 grubs that had evidently emerged from the egg- 

 several days before. Here then we find the beginning 

 of the idea of a more permanent nest, of attachment 

 to a particular spot, and of a more lasting maternal 

 solicitude. It is interesting also to note that fre- 

 quently a number of individuals of this species will 

 nest side by side in the same small patch of ground. 

 Such an association renders it conceivable that the 

 neighbours may help one another, but here direct 

 evidence is wanting and will be very difficult to 

 obtain. 



Another very common genus of Sphegid sand- 

 wasps, though small both in the number of species 

 and in the size of the individuals, is known as 

 OxyMns (the swift- darter). O. imiglumis is the 



