377 
It is not the object of this note to enter into a description of the 
species of Hippelates mentioned above. The}' are carefully described 
by Loew in his "Centuria?," and the characteristic features of two 
species [H. flavvpes and E. plebejus) are well set out by the accompany- 
ing illustrations, which were drawn by Miss L. Sullivan, under super- 
vision of Mr. Coquiilett. It suffices to say here that in form of body, 
general appearance, and mode of locomotion the Hippelates resemble 
our common house fly, but they are much smaller than the latter, aver- 
aging not more than about 1.75 mm . in length. In spite of their small 
size they are, when alive, quite conspicuous hy the bright color of the 
legs and of a part of the abdomen, which, in the case of H. flavvpes and 
H. pusio. strongly contrast with the brilliantly black color of head and 
thorax. In H. plebejus almost the entire abdomen is yellow, but the 
forepart of the body is opaque and grayish. A peculiarity of Hippe- 
lates is the hardness of their bodies, and a slap with the hand which 
would be sufficient to crush any mosquito or house fly does not hurt 
them in the least. 
Notes on the habits. — The flies are strictly diurnal, and continue to be 
troublesome from early morning till near sunset, being most aggressive 
during the hot and sultry hours of the afternoon. They preferably 
frequent open and sunny places, while in the shade of dense forests 
their presence is not noticeable. They are equally troublesome in the 
open country away from human habitations and in the streets of small 
towns, but I do not recollect having seen them in any number on the 
streets of the larger cities. They enter the houses, but evidently do 
not feel at ease in the rooms, for they do not attack people, but con -le- 
gate on the panes of the windows if these happen to be closed. When 
Fig. 38. — Hippelates plebejus: much enlarged (original). 
