348 AFFECTION OF INSECTS FOR THEIR YOUNG. 



ceiving the hole, took up the spider and dragged it in 

 after it. 



In the two instances above given, one dead caterpillar 

 or spider only was deposited in each hole. But an in- 

 sect described by Reaumur under the name of the ma- 

 son-wasp {Epipojie spinipes), very common in some parts 

 of England, after having excavated a burrow, with an 

 ingenuity to which on a future occasion I shall draw 

 your attention, places along with its egg as food for , the 

 future young, about twelve little green grubs without 

 feet, which it has carefully selected full grown and con- 

 veyed without injuring them. You will inquire, Why 

 this difference of procedure? With regard to the choice 

 of a number of small grubs rather than of one large ca- 

 terpillar, what I have said in a former letter on the sub- 

 ject of different species of this tribe being appointed to 

 prey upon and thus keep within due limits the larvae of 

 different kinds of insects, will be a sufficient answer. Buf 

 one circumstance creditable to the talents of the mason- 

 wasp as a skilful purveyor should not be omitted, namely, 

 that the number of grubs laid up is not always the same, 

 but is exactly proportioned to their size, eleven or twelve 

 being stored when they are small, but only eight or nine 

 when larger. With respect however to the caution of 

 the wasp in selecting full grown grubs and conveying 

 them uninjured to her hole, a satisfactory explanation 

 may be given. If those that are but partly grown were 

 chosen, they would die in a short time for want of food, 

 and putrefying would destx'oy the inclosed egg, or the 

 young one which springs from it. But when larvae of 

 any kind have attained their full size, and are about to 

 pass into the pupa state, they can exist for a long period 



