588 
DIPT BRA. 
loss among mules, horses, cattle, sheep, hens, turkeys, pigs, dogs, and 
cats. Smoke or Kerosene are preventives. The larvae of all the known 
species appear to live in quickly running water, which explains the 
general absence of Simuliids from the plains. Larvae have, however, 
been observed in quite a slow stream near Igatpuri, while two adult flies 
have been taken during the hot weather at Pusa, though no larvae 
have been discovered in the rather sluggish river which is the only 
running water there. The nearest rapid stream is probably at least fifty 
miles away. The larvae are curiously adapted for their mode of life, 
having a sucker at the end of the body, wherewith to cling to stones, 
a foot-like process on the 1st thoracic segment, and large brush-like 
mouthparts, whose motion sweeps into the mouth the microscopic 
water-plants on which the creature feeds. The larva can spin threads 
which help to protect it from being carried away by the rushing water, 
and when full grown it spins a pocket-shaped cocoon which is stuck to 
stones and in which it pupates ; the pupa has two much-branched 
breathing filaments which project from the open front of the cocoon. 
(PI. LXI.) The fly emerges under water and floats to the surface, 
protected from getting wet by a bubble of air or gas entangled among the 
hairs on the legs and body. In the figure of the wing (PI. LXI, fig.l). 
it will be seen that the strengthening of the anterior veins at the 
expense of the posterior ones has been carried much further than in 
the Bibionids, the only well marked veins being the costa, subcosta, 
the 2-branched radius, and the basal part of the media connected with 
the radius by the anterior cross vein. Some other small flies, e.g., 
Phoridce, have a venation at first sight somewhat similar to this, 
but their antennae are quite different to those of SimMlium. (PI. 
LIX.) 
The eyes in this family contain both large and small facets (see Bibio - 
nidce ), and afford an easy means of distinguishing the sexes, since the 
male eyes touch while those of the female are separated. The flies are 
usually coloured with some combination of grey, black, and golden 
yellow. The Indian species have not been properly studied, only 
Simulium indioum , Bech (Ind. Mus. Notes), and S. indianum, Big., having 
been described, and when the species of the hill districts have been 
collected there is little doubt that they will be found to include a con¬ 
siderable number. 
