DIPTEROUS HOSTS OF STILPNID ICHNEUMONS. 33 



DIPTEROUS HOSTS OF STILPNID ICHNEUMONS. 

 By Claude Morley, F.Z.S., &c. 



My article upon the ubiquitous Atractodes tenehricosus, Grav. 

 {vestalu, Hal.), in * Ichn. Brit.,' ii, 1907, p. 247 — wherein read 

 " mandibles " for " cheeks "at 1, 17 — concludes with the assertion 

 that " I can find no record of its parasitism " ; and I am now 

 satisfied that none had been published up to that time. Con- 

 sequently, it is very satisfactory to put on record later discoveries 

 respecting this Ichneumonid's economy, and the latest of these 

 is so definite an example that I hasten to publish it. 



Two puparia, bearmg a stout horn on either side above the 

 anus and another bifurcate nearly to its base below it, were 

 shaken by Mr. J. W. Carter from the moes of a mountain stream 

 while searching for the Staphylinid beetle, Lestiva luctiiosa, on 

 May 20th, 1918, at Malham, near Settle, in West Yorkshire. A 

 week later there emerged from one of these puparia the common 

 Anthomyid fly, Melanochila {Calliophrys) riparia, Fin., 5 , and 

 from the other similar puparium the equally common Stilpnid 

 ichneumon, Atractodes tenebncosnx, Grav., ? , which is thus 

 conclusively proved to destroy M. riparia after the latter has 

 pupated. 



This parasite probably attacks numerous species of Anthomyid 

 Diptera, for I have examined a pair that alone were bred, the 

 $ ut the end of March and the <y on May 2nd. 1914, from 506 

 puparia of Chortophila brassicce, Bouche, by Mr. J. T. Wadsworth, 

 and recorded bv him in the • Annals of Applied Biology,' ii, 

 p. 159, July, 1915. 



These definite observations go to show that the position of 

 the Stilpnides (whereof Atractodes forms part) is at length 

 correctly settled near Phygadeuon, since at least some species 

 of the latter genus are known to equally prey upon Diptera. 

 In 1907 there were no more than Brischke's record of Stilpuns 

 gagates from Anthoinyia radiciiin (' Schr. Nat. Ges. Dantzig,' 

 1882, p. 178), and Thomson's of Exolytm' incertus, " Utiackt ur 

 en %/'jj/i?VZ-puppa " (' Opusc. Eutom.,' x, 1884, p. 1021) pointing 

 in this direction ; while on the other hand the former author 

 himself thought he had bred other species of the same tribe 

 from sawflies, and there are (' Entomologist,' 1881, p. 139, and 

 1882, p. 223) records from Lepidoptera. These may now safely 

 be accounted errors along with the rearing of Stilpuns depla- 

 natus, exhibited at a meeting of the South London Entora. Soc. 

 on March 24th, 1887, " bred from the larva-case of a species of 

 Psyche found on a fence in a garden at Peckham." If further 

 proof of Dipterous hosts were requisite, it is supplied by a ^ 

 and two ? $ of Atractodes bicolor, Grav., which were sent me, 

 raised, too late for inclusion in his paper on " Observations on 



