December, 1896.] 2().") 



SUEVIVAL OF ACRERONTIA ATROPOS AFTER BEINQ STRUCK BY 

 AN ICHNEUMON. 



BY THE EET. T. A. MARSHALL, M.A., F.E.S. 



Nothing is more certain in general than the death of any Lepi- 

 dopterous insect infested by an ichneumon : in some cases it perishes 

 while still a larva, in others the chrysalis is formed before death, but 

 as a rule, the imago is never produced. The following fact, however, 

 shows that under artificial circumstances a different result is possible. 



My friend the Rev. A. P. Morres, of Salisbury, has frequently 

 reared caterpillars of Acherontia Atropos found in a potato ground 

 near that city ; he generally forces them by artificial warmth, which 

 in no way interferes with their healthy development. One of these 

 caterpillars, bred under these conditions during the present year, at- 

 tained its full growth and went underground in the usual way, emerging 

 about six weeks afterwards as a perfect moth. On proceeding to stuff 

 the body, Mr. Morres was surprised to find in the inside a large para- 

 sitic maggot, which he has sent to me. It is upwards of 10 millimetres 

 in length, with a stout cylindrical body, at first of a greyish-pink, but 

 becoming, after exposure to the air, dull olive-green. A minute de- 

 scription of it would be useless, the species being unknown, and the 

 general appearance of these creatures having been often described. 

 Probably it belongs to one of the true Ichneumons of large size, which 

 are known to be solitary parasites, and are more likely than others to 

 select the SphingidcB as appropriate victims. 



Prom the caterpillar point of view, we have here only an instance 

 of tenacity of life under trying circumstances ; any further considera- 

 tions must be based upon theory, and Mr. Morres's supposition seems 

 to be the only one admissible. He remarks that the Atropos larva 

 when first brought to him was about two-thirds grown, and exhibited 

 a black speck on its body, whence he inferred that it had been attacked 

 by some parasite. In the normal course of things the death of the 

 Atropos larva after its change to a chrysalis, and the production of a 

 living ichneumon, would inevitably have taken place some time next 

 spring. But the development of the chrysalis having been artificially 

 hastened, the parasite had no time to cause its death, and the exhaustion 

 of vitar juices was not suflBcient to prevent the final metamorphosis. 

 Hence the phenomenon of a half-grown parasite being found in the 

 body of a perfect moth. 



The eventual death of the moth from the action of the parasite 



is probable, but not quite certain. It would seem to depeiul iqiou 



■/. 



