Descriptions of British Diptera. 213 



in a point ; style three-jointed, first joint short and indistinct, second 

 dilated, and having a pointed appendage at the apex turned down- 

 wards, third longer and tapering to a point (Fig. 2) ; proboscis hori- 



zontal and directed forwards ; labrum slender and rigid : the tongue 

 rather longer and likewise very slender ; labrum slenderest in the 

 middle, and terminating in two lobes (Fig. 4:) palpi very small, trun- 

 cated and pilose : head very large, the crown transparent and with- 

 out ocelli : forehead wide in both sexes : abdomen usually much 

 narrowed at the base, and curved downwards at the hinder extre- 

 mity ; the fourth segment in the male provided with a curved horny 

 appendage on the underside : legs rather long and robust; the thighs 

 slightly compressed before the apex : wings scarcely reaching to the 

 apex of the abdomen, laid horizontally along the body when at rest, 

 the first posterior cell closed and pediculated ; the anal one elongat- 

 ed. (Fig. 6) 



The insects of this genus have a very peculiar aspect, arising from 

 the great size of the head, narrow base of the abdomen, and the in- 

 curvation of its extremity, which renders them little likely to be 

 confounded with other tribes even by the most inexperienced ob- 

 server. Their prevailing colour, which is black with marks and 

 bands of yellow, gives them at first sight something of the appear- 

 ance of wasps or small ichneumons. They are autumnal insects, 

 seldom appearing in force before August, and the more common 

 kinds continue to frequent the common ragwort and other late 

 flowering plants till the end of October. Notwithstanding the for- 

 midable appearance of the long exserted proboscis, their habits are 

 quite innocuous, the whole of their sustenance being derived from 

 the juices of flowers. Baumhauer was the first to discover that the 

 larvae are parasitical, and that they live in the bodies of humble 

 bees. Latreille has witnessed the species named rufipes issue in 

 its adult state from the body of a bee by the incisures of the ab- 

 domen, and similar observations have been made by other naturalists. 

 Upwards of twenty difi'erent kinds are known, only eight of which 

 appear to inhabit Britain. 



VOL. II. NO. 9. p 



