Nov., '03] ENTOMOLOGICAL NEWS. 29I 



A Dexiid Parasite of the Sow-Bug. 



By C. T. Brues. 



During the past summer while collecting insects near Woods 

 Hole, Massachusetts, I chanced upon a specimen of the sow- 

 bug Porcellio which had evidently been dead for some time. 

 On rolling over the log under which it was concealed in com- 

 pany with many living specimens of its ow^i species, the chiti- 

 nous remains were accidentally broken apart, disclosing within 

 its body the orange-colored puparium of a fly. 



This attracted my attention, and was brought home in hopes 

 of obtaining the adult fly. After some days the latter ap- 

 peared, a small, intensely black Dexiid. It proved to be a 

 member of the genus Melanophora Family Dexiidae, and agrees 

 very well with the description given by Schiner (Fauna Aus- 

 triaca, II) of Melanophora roralis Linn., a species common to 

 both Europe and North America. 



The larvae of another European species of this genus, heli- 

 civora, has been found by Goureau (Ann. Soc. Ent. France, 

 II, I, 77), in a snail {^Helix conspurcata^ , upon which it is evi- 

 dently parasitic. Shimer has described a species from Illinois 

 parasitic on the Chrysomelid beetle Diabrotica. From his 

 figure (Am. Nat. V, 219), it is probable, however, that the 

 fly is not a Melanophoi^a at all, since the first posterior cell is 

 open and not closed by a long petiole as in the other species of 

 the genus. 



The puparium of M. roralis is deep orange yellow in color, 

 with the anal respiratory tubercles blackened. It is quite 

 smooth and shining except at the posterior tip, and measures 

 5mm. in length, which is about the size of the adult fly. It 

 occupies almost all the available body space in the parasitized 

 Porcellio. 



The species of Porcellio from which my specimen was bred 

 is probably P. scaber Latr., and is extremely common at Woods 

 Hole under fallen logs. The fly is of general occurrence in 

 the same region, although never very common. 



Mr. J. Chester Bradley has entered Cornell University, and his ad- 

 dress is 325 Dryden Road, Ithaca, New York. 



