1908] GIRAULT — PECULIAR CASE OF PARASITISM m 



be a large hymenopterous (or dipterous?) larva, filling the body cavity, and to one 

 side, two dead females and a dead pupa of the Tritneptis, But from the appearance 

 of this dead larva, it did not seem to have been parasitized but dead from pathological 

 •causes, and the case may have been one of double parasitism. However, it tends 

 to throw doubt on the nature of the parasitism of the species in (juestion. It may 

 also be mentioned that the parasites were mainly found in the abdominal cavities 

 of the host pupae, a fact which also indicates hjq^erparasitism; no traces of other 

 parasites, however, coidd be found, and the evidence points to primary parasitism in 

 both cases. 



Howard (1897) mentions a case somewhat similar to the foregoing in speaking 

 of the common hyperparasite of- this host, DibracJujs boucheanus (Ratzeburg). 



Quoting: — "A singular and practically inexplicable instance was observed 

 December 16, 1896, where in a cocoon of the Orgyia a dead female chrysalis was 

 found in an advanced stage of development. The moth was apparently just ready 

 to emerge at the time of death. All of the scales on the body and legs were fully 

 formed and the wings were also fully developed. On breaking the body across, in 

 the interior of the abdomen were found two active living larvae, which were entirely 

 indistinguishable from the larva of this species. The specimen was put aside to 

 await developments, and the writer has at this time no explanatory comments to 

 make." (A footnote is then appended giving reference, among others, to T. A. 

 Marshall in Entomologist's Monthly Magazine, Dec, 1896, where an ichneumonid 

 larva is recorded as having been found alive in the body of an adult Acherontia atro- 

 pos). It seems to me that these cases can be explained by considering that the para- 

 site attacked the host late in its development and in smaller numbers than usual, 

 and at a time when its resistance was high or the parasite was unable to come to 

 maturity before the host had fully developed. It would then be found in the abdomen 

 of the adult, or if in sufficient numbers and early enough may overcome the host just 

 previous to the final ecdysis. This view is supported by the fact that we know of 

 cases of unusually late attack on the part of some parasites. Thus instead of attack- 

 ing the third grown or younger larva, it attacks the full-grown larva or even the pupa. 



In passing, attention should also be called to the fact that the female pupae only 

 were infested with these parasites. 



