of Rhipiphorus paradoxus. 395 



grown, and therefore not previously in a suitable condition for 

 the larva of the parasite to feed upon. 



The larva of RM])iphorus^ attached to that of the wasp 

 which I possess, is about one-third of the size of the larva of 

 its victim. In three instances Mr. Murray found a pupa of 

 the wasp and also that of RMpijjJiorus in the same cell, which 

 is considered conclusive against the idea of one feeding upon 

 the other ; and it is assumed that they must have been hatched 

 in the same cell, bred lovingly together, and have undergone 

 their metamorphoses in the same cell. 



I confess to the difficulty of satisfactorily accounting for 

 this ; but it is a well-known fact that parasites do, in some in- 

 stances, feed upon the larvse of insects without destroying 

 them ; this is of course in cases where the nourishment required 

 by the parasitic larva does not injure or destroy the vitality of 

 the larva preyed upon. StT/Iops is an instance of this kind ; 

 and I have bred a species of Tachina and a perfect example 

 of Saperda ^opulnea from the same cell. Other instances of 

 the kind might be readily adduced ; and it may be possible 

 that in the instances mentioned by Mr. Murray the larva of 

 Bliipijjihorus did not consume the whole of the wasp-larva, did 

 not, indeed, destroy its vitality : these pupae are described 

 as being stunted ; and such may be the explanation. Be 

 this as it may, from some cause or other, parasites (I do not 

 assert that all do so, but many species) vary in size most 

 astonishingly. No better instance of this can be mentioned 

 than that of the common ruby-tailed fly, Chrysis ignita : this 

 parasite I have myself reared from cells of Odynerus 'parietum 

 and 0. antilope ; I have also bred them from the nest of Vespa 

 vulgaris j and I have bred them from the cells of Osmia 

 hicornis. Osmia parietina has also a species of Chrysis para- 

 sitic upon it ; I bred it myself. Now, unless we conclude that 

 Chrysis is a general feeder, that at one time it is nourished 

 upon lepidopterous larvae stored up by Odynerus^ then that it 

 is fed by the social wasp V. riifa^ and lastly that it feeds in 

 the nests of Osmia upon pollen and honey, we must con- 

 sider it to be a carnivorous parasite, and that it feeds upon the 

 larvae of the insects whose nests it infests. 



Now, I repeat, I know of no parasite that differs more in 

 size than Chrysis ; and this must, I think, be attributable to 

 variation in the amount of sustenance they obtain : this would 

 certainly be very great in the instances I have enumerated of 

 the larvae of Vespta, Odynerus, and Osmia. I possess examples 

 of C. ignita varying in length from 3| to 7 lines. I may also 

 instance, as examples of parasites that differ greatly in size, 

 the genera Sitaris, Meloe, and Rhipiphorus. 



