264 ORDER DIPTERA 



The liead is yellowish-brown, nearly square, horny, and 

 marked as in the figure (Fig. 208). 



The tip of the abdomen is crowned with rows of hooks, 

 and on the up])er side of the abdomen is the set of breathing 

 organs, which have been mentioned heretofore. 



The larvaj are fovmd more particularly attached to sub- 

 merged logs, wholly or partly submerged stumps, brush, 

 bushes, and other like objects in the larger creeks and bayous 

 of the region to which they are common. 



B.-^*V ''l-'-rsf 



Fig. 211. — Sirnulium pecuantm: head of m.'ile ;it riglit ; head of female 

 at left — greatly enlarged. (From Annual Report of Department of -Xgri- 

 culture, 1886.) 



When fully grown the lar^•^e descend to near the bottom 

 of the stream, sometimes eight to ten feet, to make their 

 cocoons. 



The cocoon upon these leaves is conical, grayish or brown- 

 ish, semitransparent, and has its upper half cut square off, 

 more or less ragged, as if left unfinished. Its shape is irregu- 

 lar, the threads composing it very coarse, and the meshes 

 rather open and ordinarily filled with mud. They are not 

 always fastened separately, but frequently crowded together, 

 not forming, however, such coral-like aggregations as in some 

 of the Northern species. The larva in spinning does not 

 leave its foothold, but running in the centre of its work, uses 



