On the Chaetotaxy of Cacoxemis indagator Lw. 411 



aa. No longitudinal vein between the first and fourth longitu- 

 dinal veins; wing fig. 2; eyes contiguous (c/). 



Hammatorrhina Lw. — H. hella Lw-cf. — Ceylon. 



AA. Proboscis short; bind tibiae without spurs; ungues pulvilli- 

 form; wing fig. 8; eyes contiguous [or subcontiguous?] {cf). 

 Hapalothrix Lw. — H. luguhris Lw. cf — 



Europa. 



On the Chaetotaxy of Cacoxenus 

 indagator Lw. 



by C. R. Osten Sacken. 



Cacoxemis indagator is a little fly, between 3 and 4 mm. long., 

 which was first observed in Silesia by Dr. Scholz in sand-pits, fre- 

 quented by sand-burrowing bees; a little later Dr. Giraud (Verb. 

 Z. Bot. Ges. 1861, p. 489) bred it from the nests of Osmia emar- 

 ginata, found on old Avalls. The larva of the fly consumes the 

 provisions gathered by the bee, and thus reduces the progeny of its 

 host to starvation. Loew recognized a new genus in this fly, gave 

 it a well-chosen name {Cacoxenus = bad guest) and described it in 

 a Short paper (Wien. Ent. Mon. 1858, p. 213—222), a very niodel 

 of accuracy and completeness. The only point, in which the de- 

 scription is incomplete, is the enumeration of'the macrochaetae, 

 especially of those of the thorax. I shall attempt to fiU this deficiency 

 by applying to tliis fly my chaetotactic System, as described in the 

 Trans, of the Entom. Soc. of London 1884, p. 497—517. 



My specimens of C. indagator I find on the Windows of my 

 rooms in Heidelberg, three or four of them regularly every spring, 

 during the first half of May; they may be the guests of some mason- 

 bee nesting along the walls of the house.i) I have now about a 



i) Mr. Raddatz fonnd C. indagator in the same Situation; compare 

 his Dipt. Mecklenburgs, in the Archiv des Vereins für Naturwiss. in 

 Meclilenburg, 1873. 



