AQUATIC INSECTS IN NEW YORK STATB 345 
Hungary the eggs of S. columbatczense midge have 
also been studied. When first laid, they are enveloped in a 
yellowish white slime, which becomes darker, till, finally, it 
becomes black just before the emerging of the larva; the egg 
stage lasting about a week. For further notes on the eggs of 
Simulium see New York State Museum bulletin 47, 1901, page 
408. 
Larva. The larval stage of the known species lasts about 
four weeks in the summer, though longer in the cold weather. 
It is in this stage that it hibernates. Swift flowing water is 
essential to its life; if removed to quiet water, it dies within a 
day, and usually in a few hours. Fastened to the rock, twig 
or leaf by the anal end of the body, it assumes a more or less 
erect position and moves its head occasionally with a circling 
motion. It is able to move about on the surface of the rock 
or sides of the vessel in which it may be placed. Its manner 
of progression resembles that of the larva of a geometer moth, 
though not so rapid. Attaching itself by means of its thoracic 
proleg, it draws up its body in a loop, then, attaching itself by 
means of its caudal sucker, it releases the hold of its proleg. 
According to the unpublished observations of Miss R. Phillips 
(of the class of 1890, Cornell University), the larva feeds on 
algae, as Nothix, Cladophora, Vaucheria, on diatoms and parts 
of phanerogamous plants. Sand also has been found in the 
digestive canal. | 
Structure of the larva. The full grown larva of even the 
largest species does not exceed 15mm (about 2 inch) in length. 
The body is somewhat cylindric in shape, enlarged at both 
ends, attenuated in the middle, the posterior half much stouter 
than the anterior part, and almost club-shaped [pl.34, fig.9]. 
Besides the head there are 12 poorly defined segments, the first 
two of which consolidate shortly before pupation. The color of 
the larva varies with the species, and perhaps also, to some 
extent, with the nature of its food. Some are a deep shining 
‘black, with paler incisures; others gray, yellow or dark green; 
iin some the ventral surface is much lighter than the dorsal, 
