72 H. C. EFFLATOUN. 



ERISTALINiE 



Antennae moderate in shape and length, drooping; arista 

 dorsal and always bare in the Egyptian sr>ecies. 



Wings with the radio-median cross-vein at, or after, the 

 middle of cell M2; Radius 4 + 5 with a deep sudden loop down- 

 wards at about the middle of cell R5; cell Rl either closed or 

 open. Legs usually simple, but the hind femora sometimes thicke- 

 ned and curved, with a dilatation just before the apex. 



Many of the members of this sub-family (especially the Euro- 

 pean and Exotic genera) seem to mimic bees and all may be known 

 by the peculiar loop irr the cubital vein. The metamorphoses of 

 many European species have been studied and nearly all approx- 

 : naie to the well known "rat-tailed" larva of Eri stalls tenax. 

 These live in liquid mud or filth and the long anal process can be 

 extended or diminished by the larva according to the varying 

 depth of the liquid in which it exists. I have found the larvae of 

 Eristalis in various stagnant ponds near Cairo in company with 

 the rather familiar and similar larva of Hirtea anubls (Stratio- 

 miidae). 



I have also watched the adults of E. tceniops and (eneus 

 hovering and resting over the edges of these ponds and in all 

 probability they were ovipositing. I have further found larvae of 

 Eristalis in a water tank containing macerated bones, at the 

 School of Medicine, in conjunction with Psychodid and Culicid 

 larva" and have watched the female of E. tceniops hovering over 

 this tank and ovipositing in the moist chinks and cracks of the 

 floating bones. 



The only representatives of this sub-family in Egypt belong 

 to the two great genera Eristalis and Helophilus which contain 

 most of the species and which are represented all over the world. 

 However the true Helophilus does not seem to be represented here 

 (nor apparently in North Africa) but those that do occur belong 

 mainlv to the Sub-Genus Mesembrius. 



