138 



it seems that the wasp-grub entirely disappears, any portions held in the 

 mouth of the Rhipiphorus merely meaning that the latter has not quite finished 

 its meal ; even the head and jaws of the wasp appear to be swallowed. The 

 larva of Rhipiphorus, as it becomes full-fed, evacuates an insignificant amount 

 in the form of a few small reddish pellets. 



I can see no difference between the silken dome over a normal wasp-grub 

 and that over a Bhijpypkorus. I mention this not to show that Rhipiphorus 

 does not spin it, which is sufficiently clear, but to show that it is not interfered 

 with by the proceedings of Rhipiphorus, and that the wasp-larva is able to 

 spin it as usual, although it is attacked before it has begun to spin. Neverthe- 

 less, although the silk is the same, as soon as the Rhipiphorus-\&x\& has grown 

 at all, the cell is easily detected. It looks decidedly whiter than the sur- 

 rounding cells, from the larva or immature pupa of Rhipiphorus shiniDg 

 through. The larva of Rhipiphorus is much whiter than that of the wasp ; and 

 the pupa is quite white, whilst that of the wasp has two large brown or black 

 eyes. As the time of emergence approaches, the Rhipiphorus-ceW looks blackish 

 or reddish as compared with the greenish tint given to the silk by the shining 

 through of the black and yellow face of the wasp. 



Ragged holes may frequently be observed in the silken dome covering the 

 Rhipiphorus-cells. These are not to be found over those that are still small, 

 but over full-grown larvee and pupre ; they may frequently also be seen over 

 healthy wasp-pupre. They are evidently made by perfect wasps, who investi- 

 gate everything that appears unusual in the cells, with the apparent object of 

 removing a dead larva ; at any rate, the presence of a living Rhipipihorus-laxva, 

 seems to satisfy them as well as one of their own pupa?. 



The wasp-grubs and pupa? always face towards the centre of the comb, 

 those of Rhipiphorus, as follows from its mode of devouring its victim, always 

 face in the opposite direction ; they look to the outer angle of the cell, rarely 

 to the one next it on either side. The perfect Rhipiphori emerge about two 

 days after the wasps of the same row. 



I do not know the time required by Rhipipihorus to go through these 

 changes ; it is something more than that required by the wasp from spinning- 

 up to emergence ; but what this is I do not know. That this is much less in 

 the nest naturally than in the captive comb is almost certain, as the tem- 

 perature of the nest is, no doubt, very high. In captivity it is twelve or fourteen 

 days. Even this period is quite compatible with a larva of Rhipiphorus of about 

 five millims. growing in two days large enough to fill up the top of the cell, as 

 we see it does before it is full grown ; and this was doubtless what Mr. Stone 

 saw, as the Rl^nphorus-l&rva becomes a pupa at about the middle of the 

 period of twelve or fourteen days mentioned above. 



In connexion with this very rapid development of Rhipiphorus, the follow- 

 ing fact is very interesting. Many larva?, when about to assume the pupa- 

 state, present obvious indications of the eyes of the imago beneath the skin of 

 the second or even of the third segment. This, we have just seen, occurs in 



