Note upon a Tachinid Parasite (Bucentes geniculates, T). G.). 233 



the head, touching things with it, but they were never seen to probe into 

 flowers, or, as far as could be judged, use it in feeding. Up till the evening 

 of 26th May both flies were lively and apparently well, but during the 

 following day one died, and on the succeeding morning the last one was 

 found also dead. 



Description of the Fly. 



As already noted the fly has been identified as Bucentes geniculatus, 

 De Geer, a member of the Family Tachinidae. This family is a very large 

 one, comprising an enormous number of species whose larvas live as parasites 

 upon other insects, chiefly caterpillars. 



The fly is blackish looking, rather smaller than an ordinary housefly 

 with numerous bristles on the body, particularly upon the abdomen, and with 

 large, pale squamae above the halteres. A distinctive generic character is 

 the long, slender filiform proboscis which is geniculated at the base and 

 at the middle. The free extremity is bent downward and directed back- 

 ward when not in use. In the act of extension, it is bent first downwards 

 and then upward and forward. The first and second joints of the antennae 

 are tawny in colour, and the arista bears very fine and extremely short 

 hairs. The legs are tawny with black tarsi. The wing characters are as 

 figured. The fly is very common, but the only account I have been able 

 to find regarding its habits is the reference given in Knuth's Handbook of 

 Flower Pollination, where it is reported as a visitor to numerous flowers. 

 As these include early and late flowering species (Viola lutea and Mentha 

 aquatica) the imaginal period probably extends through the whole summer. 

 The latter plant does not flower in this country until August. From the 

 character of its proboscis, the fly is likely to collect nectar from moderately 

 sized flowers with partially concealed nectar. Theobald mentions (Second 

 Report on Economic Zoology) having found a Tachinid in a cage in which 

 Tipulse were being reared, but from this indefinite reference one can only 

 regard the identity of the species as probable. 1 



The Larva.. 



The internal structure of the larva has not been examined. The largest 

 examples found measured 7 mm. in length, by If mm. at the broadest part 

 of the body. At each segment the body is encircled by four rows of 



1 The following records have since been found in Brauer und Bergenstamn : Die 

 Zweifliiger des Kaiserlichen Museums Zu Wien. Denk. Akad. Wiss. lxi. Bd., 1894, p. 537. 

 Siphona (Bucentes) geniculates (Fll. Bdi. Ins. p.) in Mamestra brassicce L. 

 Siphona (Bucentes) cristata (Beling. Verh. K. K. Zool. bot. G. 1886, 171) in Tipula 

 gigantea, Schrk. 



