DIPTEROUS PARASITES. 1913 



the determination of the parasite ; while one may, with much probabiHty, 

 assume that a fly bred in America from Vanessa atalanta is Exorista 

 futihs, yet it may be quite another species, and E. futihs may, with 

 much probability, be also parasitic upon some other butterfly or moth. 

 Phorocera concinnata Meigen has been found parasitic upon fi\c species 

 of Vanessidi and two species of Pieridi. So, also, Exorista vulgaris 

 Fallen has been bred from Pieris rapae, Cinclidia athalia, Procrustes 

 coriarius and Plusia gamma. 



Two species of flies belonging to very different families have been sent 

 me as having been bred from butterflj- larvae. One of these, a species of 

 Phora (89: 16), may have been parasitic upon the living larva, but, more 

 frequently, the larvae of these flies are found in decaying animal or vegeta- 

 ble matter. I cannot recognize the species among those hitherto described, 

 and the preservation of the specimen will not warrant its description as 

 new. The other, Syneches pusillus Loew, I was surprised to find, 

 among the specimens sent by Mr. Scudder, bearing the label "Lye. neg- 

 lecta larva," with tlie chirograpliy apparently that of Mr. W. H. Edwards. 

 That there miglit be no error, however, I sent the specimen to that gen- 

 tleman, who assured me that the label was his, and, furthermore, though 

 he could not recall the specimen, that there could be no possibility of 

 doubt in the labelling of the si)ecimen, as indeed no one could susjiect from 

 Mr. Edwards's known reputation. The fact is one of much interest, as I 

 cannot learn that any species of this family (Empidae) has hitherto been 

 known to be parasitic in the larval state, though the members are pre-emi- 

 nently predaceous in the adult stage. So far as I am aware, the known 

 species of this genus are confined to Europe (Pterospilus), Africa, and 

 America. A possible, if not probable, explanation of the parasitism in 

 the present case is, that the larva had entered the buttei-fly caterpillar 

 or chrysalis after hatching. The larvae of Emjiidae, so far as known, 

 live in decaying wood, humus, etc. 



The larvae of Tachinidae wiU be recognized by their headless, maggot- 

 like appearance. They are thick, cylindrical, flattened below, the seg- 

 ments distinctly separated, with transverse and side swellings, either naked, 

 or girdled with thin, short spines; the antennae are thick, wart-like, and 

 the mouth has two, slightly curved, projecting booklets. The puparium, 

 formed by the larval skin, is elongate ellipsoidal in shape, of a deep brown 

 or reddish brown color, with the ends obtusely rounded, the segmentation 

 only feebly indicated, moderately smooth, without projections, save the 

 two obtuse stigmatic tubercles at the hind end. The flies, it is needless 

 to say, are cyclorrhaphous, that is, they escape from the pupigerous lar- 

 val envelope through a chcular opening made by bursting off the anterior 

 segments. 



In addition to the species described below, there were sent me by Mr. 



