FIELD BOOK OF PONDS AND STREAMS 



Fig. 184. — Smoky alderfly, Sialis infiimata: I, 

 larva; 2, adult. 



They are active in the day time, especially in bright sun- 

 shine, usually laying their eggs at midday. These are deposit- 

 ed in fiat masses of 200-500 and there are usually several 

 masses within an area of a few inches on some leaf, board 

 or stone which overhangs rapid water, so that the lar\'ae fall 

 into the current as soon as they hatch. The eggs are C3'lin- 

 drical, dark brown, and at the end of each there is a little 

 club-shaped projection visible with a hand-lens. The eggs 

 are placed slightly slantwise to the surface with the little 

 projection pointing upward. 



The larvas (Fig. 184) live in the sandy or muddy bottoms 

 of the streams or ponds, often buried several inches below the 

 bottom surface where they are hidden from their relatives 

 and greatest enemies, the Corydalis larvae. They are brown, 

 and heavy skinned; when fullgrown they are about an inch 

 long. Each of the first seven segments of the abdomen bears 

 a pair of five-jointed, tracheal gills which are fringed with 



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