AQUATIC IXSECTS IX NEW YORK STATE 345 



Hungary the eggs of S. c o 1 u m b a t c z e n s e midge bave 

 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 

 €r 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 According to the unpublished observations of Miss R. Phillips 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 

 silgae, as Nothix, Oladophora, 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 f inch) in length. 

 The body is somewhat cylindric in shape, enlarged at both 

 <>nds, 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 

 Hack, with paler incisures; others gray, yellow or dark green; 

 3n some the ventral surface is much lighter than the dorsal. 



