1921] Bequaert — Atherix hraunsi 3 



Beaver Oi-eek, Utah. The time was late afternoon and all the flies 

 were dead." Though^ in this last instance, no specimens were col- 

 lected, this observation most probably also refers to A. variegata. 



The gregarious habit of the western Atherix has also been ob- 

 served in Utah and Idaho by Aldrich, who gives an interesting 

 account of the manner in which certain California Indians collect 

 and prepare the masses of these flies for food.^ The American 

 Museum, of Natural History possesses additional specimens of 

 Aiherix variegata obtained by Dr. F, E. Lutz at Pagosa Springs, 

 Colorado (7,800 ft.), June 22 to 24, 1919, and on the Green Kiver, 

 Wyoming (6,100 ft.), July 2, 1920. 



It is indeed well worthy of notice that the same gregarious be- 

 havior of the adult flies has now been noted in one of the African 

 species, which I have named Atherix hraunsi, in honor of its dis- 

 coverer. There is thus reason to suppose that this curious and 

 thus-far mysterious habit will eventually be observed in many other, 

 if not all, members of the genus. In a recent letter, Dr. H. Brauns, 

 of Willowmore, describes the habits of A. hraunsi as follows: "This 

 fly is of peculiar interest. It is at home along the margin of 

 swiftly running brooks near Cape Town. One flnds females and 

 males of it on stones that emerge above the water (the female is 

 smaller and black), bunched together in masses as large as a man's 

 head; every moment pieces the size of a fist break away from the 

 mass and, as soon as they drop in the water, are greedily eaten by 

 the trout with which the streams' have been stocked." 



Atherix braunsi sp. nov. 



Male. Length 6 mm. Wing, length 7 mm., width 2.4 mm. 

 Head (Fig la) broadly elliptical, as wide as the thorax; one and 

 one-third times as wide as high when seen in front ; hemispherical 

 in profile. Inner orbits gradually divergent from the vertex to the 

 side-checks. Front very broad; at its narrowest part, the vertex, 

 about half the width of one eye; at the antennae nearly half the 

 width of the head. Face short, only half as long as the front, 

 obliquely receding below; the antennae inserted on the lower third 

 of the head. Epistoma with a deep dejiression below each of the 



^ Aldrich, J. M. Flies of the I.eptld genus Atherix used as food by Cali- 

 fornia Indians. Ent. News, 23, 1912. pp. 159-163. 



