reversal is not an accident, but the normal procedure of every wasp-grub : — first, 

 that though I have found a number of grubs so reversed at this stage, I find 

 none so at further advanced stages, as would be the case were it an accident ; 

 and, secondly, although in the case of Vtspa vulgaris the silken dome and lining 

 extends with any strength only for about a quarter of an inch down the cell, 

 it extends almost to its base in a slighter form ; and in the case of Vcspa 

 Nomriica, I find a strong silken lining quite to the base of the cell. "Within 

 this silk lined cell, which is in fact a cocoon, the wasp grub completes its 

 transformation, and emerges by biting a hole in the silken dome, or cover. As 

 each tier of comb is begun at the centre, so the wasps emerge first in the 

 centre, then the next row and so on. As soon as the wasp has emerged the 

 workers remove from the cell the cast skins of the pupa, and of the larva in as- 

 suming the pupa state, but they do cot interfere with the black deposit at the 

 base of the cell. They also remove the remains of the silken dome, and cut 

 down the walls of the cell, probably to facilitate the laying of another egg 

 and the feeding of the young grub when hatched. In this way several wasps 

 are successively reared in the same cell. 



I have already remarked that the wasp-grub has little more than its own 

 bulk of food : this remark is equally applicable to both solitary and social bees 

 and wasps. In the case, for example, of Meyachile, the larva eats its store 

 of pollen-bread, evacuates a few brown-black pellets (less in quantity than the 

 black deposit of the wasp), spins a very thick and strong silken cocoon, and, after 

 a rest of about ten months, completes its transformations, and emerges a bee 

 of about the size of the original mass of pollen. Air-cavities within and a 

 thick coating of hair, of course, aid in giving the appearance of no bulk having 

 been lost. 



So much for the history of the wasp grub, to return to Rhipiphorus. I 

 succeeded on August 4, 1870, in obtaining a nest of Vcspa vuhjaris that was 

 well tenanted by Rhipiphorus paradoxic, and easily ascertained that the larva 

 of Rhipiphorus eats that of the wasp after the latter has spun up, and that the 

 Rliipiphorus completes its transformations only a day or two after the surround- 

 ing wasps. I examined this nest with some care within a few hours after it 

 was taken, and, though I observed many small larvse, I failed to find any eggs. 

 I was very fortunate in obtaining, a few days afterwards, two small nests which 

 contained abundance of Rhipiphori, for the purpose of searching for the egg. 

 My observations will, perhaps, be more intelligible if I throw them into the 

 form of a life-history of the beetle ; and this arrangement will show more 

 clearly what points require further elucidation. 



Rhipiphorus, then, doubtless lays her eggs somewhere, but where I am 

 unable to tell. I first take up the history with the young larval Rhipiphorus 

 at large in the wasps' nest, in a form not unlike that of the young larva of Mcloii. 

 It was in examining the first nest that I met with a solitary specimen of the 

 larva in this stage. I examined it under the microscope, but neither figured it 

 nor wrote a description of it at the time. Though it will be obvious, as I pro- 



