Nerve-winged Insects; Scorpion-flies; Caddis-flies 225 
Two species of Sialis occur in this country; they are called alder-flies, 
or orl-flies. The smoky orl-fly, Sialis injumata, widely distributed over 
this country, is a dusky brownish in¬ 
sect about J inch long, often seen, with 
wings closely folded, sitting on sedge- 
leaves near quiet waters. The larvae 
(Fig. 309), according to Needham, live 
in marshy places filled with aquatic 
plants, on the borders of streams and 
ponds. When full grown they are 
about an inch long, and keep up an 
undulating motion with the abdomen, 
the long tail being intermittently lashed 
.up and down. When full grown the 
larva crawls out of the water and at 
some little distance burrows into the 
moist soil for a few inches or even a 
foot or more. Here it forms an oval cell and pupates within it. Two or 
three weeks after the adult fly issues. 
Of Chauliodes, the fish-flies (Fig. 310), eight North American species 
are known. The adults are from ij to 2J inches long, and their wings 
expand from 2\ to 4 inches. The wings are grayish or brownish with whitish 
spots or bands, and the antennae are curiously feathered or pectinate. The 
Fig. 309.—Larva (at right) and pupa (at 
left) of an orl-fly, Sialis injumata. 
(After Needham; twice natural size.) 
Fig. 310.—The saw-horned fish-fly, Chauliodes serricornis, laying eggs. 
(After a photograph from life by Needham; natural size.) 
larvae live in wet places at the edge of water or in water close to the surface. 
According to Needham they are perhaps oftenest found clinging to the under 
side of floating longs or crawling beneath the loosened bark. They are 
predaceous, feeding upon other aquatic insects. When ready to transform 
they excavate a cell above the level of the water under a stone or log or layer 
