57 



numbers in their nests. For some time, though this insect was 

 found in hirge numbers in the pupa and perfect state, the larva 

 could not be found and the method of attack on the unfortunate 

 embryo wasp who happened to occupy the same compartment as 

 the assailant was unknown. On the 19th of August, l8Gi, Mr. 

 S. Stone was fortunate enough to discover one in a nest of V. 

 Vulgaris, and on proceeding to open the cell containing it he 

 found the parasite firmly attached to a full-grown larva of a 

 wasp; the mouth of the former buried in the body of the latter 

 just below the head, its neck bent over that of its victim, whose 

 body appeared to be tightly compressed by that of its destroyer, 

 showing the latter to be possessed of a considerable amount of 

 muscular power. It was of minute size when discovei'ed, and 

 appeared to have only very recently fastened upon the body of its 

 victim; but so rapid was its growth, and so voracious was its 

 appetite, that, in the course of the following -18 hours, it obtained 

 its full size, having consumed every particle of its prey with the 

 exception of the skin and mandibles, which from observations 

 made it appears these creatures retain in their grasp even after 

 they have passed into the pupa state. They appear to scarcely 

 cease eating, except now and then for a minute or so, from the 

 time they first begin to feed till they have become full-grown. 



In another nest, taken out on the 2nd September, was found 

 on opening some closed up cells appropriated to queens, one 

 larvae and one pupa which differed in nothing that could be 

 discovered from those of Rhipiphorus found in the cells of 

 workers except that they were something like double the size, in 

 fact, about as much larger as the larvae and pupae of Queen wasps 

 are larger than those of workers. 



It appears, like some of our butterflies, such e.g. as C. 

 Edusa and V. Antiopa, to disappear altogether during some 

 seasons and then to reappear in more or less considerable numbers. 



In the year 1859 Rhipiphorus was found in Cokethorpe 

 Park, Oxfordshire, but, though diligent search was made for it 

 in the following years, not a single specimen was discovered there 

 till the year 18G-1, when those I have described were found. 

 What had become of them during the intervening summers is a 

 question more easily asked than answered. Like many other 

 insects, P. Machaon and P. Actaeon, for example, these parasites 



