1920.] 



149 



I 



A larva of a third species, jllaseocJutra valida Lcc, has been seen to 

 gnaw its way into the i)upariiiin of a Syrphid fly, Copesfylum margi- 

 natum* In each of these cases the host is Dipterous, but Wadsworth 

 (op. cit., p. 15) cites an instance in which there is strong presumptive 

 evidence that yet another species, Aleochara lata, was bred from a Hy- 

 menopterous host : the beetles were found (in Canada) in a breeding- jar 

 containing cocoons of sawflies, but, as parasitism was not then suspected, 

 it was not ascertained whether they had actually emerged from the 

 cocoons. 



In the only one of these species whose life-history has been com- 

 pletely studied — namely, A. hilineata — the larva is a true parasite, since 

 it is essential for its development that it should enter some kind of 

 Dipterous puparium. Tlie eggs are deposited in the soil, and the young- 

 larva gnaAvs its way into a puparium, and remains during its develop- 

 ment in the space between the puparium and the cuticle of the enclosed 

 nymph of the fly, on which latter it feeds. In its second and third 

 stages the larva of the beetle differe widely from the active first-stage 

 larva, and in its swollen shape, weaker cuticle, changed form of antennae 

 and mouth-parts, and absence of tarsal claws and anal cerci the older 

 larva presents features characteristic of a real parasite. 



Beeedii^& of Aleochara algahum. — The puparia of Orifr/ma 

 hictuosum Meigen, two of which were found by Mr. Lyle each to con- 

 tain a specimen of this beetle, were collected by him at Osmington 

 Mills, Dorset, on September 22nd, 1912, at the foot of the cliff, lying 

 on clayey mud among pebbles and covered by a shallow layer of seaweed. 



On September 12th and 13th, 1919, at Durlston Bay, Swanage 

 (Dorset), I collected a large number of puparia of Phycodromidae in 

 the hope of breeding the parasite from them. These daj^s were very 

 hot, and many Phycodromids and other flies were flying over the rocks 

 and the thick beds of decaying seaweed. From time to time, when I 

 lifted a big stone, great numbers of Phycodromids would come buzzing 

 out from beneath, and some of them looked as though newly emerged 

 from their puparia. Deep down — sometimes nearly a foot deep — under 

 the seaweed, among large stones and decaying weed, were masses o!:' the 

 puparia, frequently stuck fast together in groups or in neat little bundles 

 of about six to ten. Most of these puparia were empty, the flies having 

 already emerged ; but I succeeded in collecting a considerable munber 

 from which the flies were not yet emerged, though these latter i)U[)aria 

 were more often found singly and not in the Inmdles, a state of things- 



* D. W. Coquillct," Atidther p^irasitic Kovp-b.'.'tlc." lusci't Life. iii. IS91. I'p. .118-9. 



