97 



note on the supposed larva op pimpla ocu- 

 latoria, f., figured in morley's 'british 

 ichneumons; vol. hi., 1908, and its location 



AMONG the DIPTERA. 



By J. E. Collin, F.E.S. 



Mr. Claude Morley has described and figured on p. 114 

 of his latest volume on British Ichneumons what he supposed 

 might be the larva of Pimpla oculatoria, F., found in an egg-bag 

 of Epeira diademata, taken from under the coping of a garden 

 wall in Ipswich ; this larva cast its skin soon after he found it, 

 but ultimately died. 



To Mr. Morley this was an " ichneumonidous larva of most 

 unusual form and colour;" still, the known fact of the asso- 

 ciation of P. oculatoria with spiders, and of its having been bred 

 from the egg-bag of this particular spider, naturally led him to 

 believe that the connection between the larva he found and the 

 ichneumon, though " unsatisfactory," was " extremely probably 

 correct." 



My attention was attracted to his figure by its great simi- 

 larity to the larvfe of some Diptera, while the fact that Mr. 

 Morley had found in another egg-bag of the same spider given 

 to him by the Rev. 0. Pickard-Cambridge one similar larva- 

 skin with "the very distinctive rostrum of the . . . described 

 larva," and in the same egg-bag were four cocoons of the 

 Pimpla, favoured the conclusion that this must be a Dipterous 

 larva with the Pimpla parasitic upon it. 



Mr. Morley generously allowed Dr. Sharp to examine the 

 larval skin, and he writes : " It is no doubt that of a Dipteron 

 of the family Stratiomyidge. From its appearance it may have 

 been parasitised ; it has, at any rate, not been naturally cast oft"." 

 It would therefore appear that there must be a species of 

 Stratiomyidae, living in the larval state upon the eggs of Epeira 

 diademata, though the present knowledge of the larval habits 

 of the family in no way supports the possibility of such an 

 occurrence. The only genus of Diptera in the neighbourhood 

 of the Stratiomyidae, said to have been bred from the cocoons of 

 spiders, is Acrocera (Cyrtidge), but the presence of Acrocera in 

 the middle of Ipswich would be somewhat remarkable. 



It remains for someone to clear up this interesting question 

 by rearing one of these larvae, which unfortunately Mr. Morley 

 failed to do. 



[That the attack upon the spiders' egg should be in the 

 form of hyperparasitism has never before been suggested, and 

 certainly did not occur to me when writing my article upon 

 the subject (Ichn. Brit. iii. 113-115), which is certainly worthy 

 of very close attention (cf. Grav. Ichn. Europ. iii. 154 ; Westw. 

 Mod. Class, ii. 143; Laboulbene, Ann. Soc. France, 1858, p. 800, 



ENTOM. — APRIL, 1909. I 



