AQUATIC INSECTS IN THE ADIRONDACKS 543 



shores of a pond at Galesburg 111. black with these flies about the begin- 

 ning of June. 



Several adults were taken on both Little Clear and Big Clear creeks, 

 during the latter half of June. Larvae were obtained in small numbers 

 from Little Clear creek on the hatchery grounds. No attempt was made 

 to rear them. I have reared the species in Ithaca N. Y. in 1897. Larvae 

 obtained here agree entirely with others from Ithaca and from Galesburg 

 111. 



The larvae live in trashy places filled with aquatic plants in the borders 

 of streams and ponds. They clamber through fallen vegetation with 

 great agility, and push their way readily through sediment fallen on the 

 bottom. In an aquarium, and probably outside, the abdomen maintains 

 an undulating motion, the long tail being intermittently lashed up and 

 down. This causes a swirl in the water, which is doubtless useful in bring- 

 ing a fresh supply of water into contact with the lateral filaments. 



The larvae, when fully grown, transform in moist soil at some little 

 distance from the edge of the water. At a. depth of several inches or a 

 foot or more, depending on the character of the soil, an oval cell is 

 formed in which the larva curls itself up, and without making a cocoon 

 becomes a pupa. Two or three weeks after the making of the pupal cell 

 the adult fly emerges. 



Excellent available accounts of European species of Sialis are: 



Pictet, F. J. M6moire sur le genre Sialis Latreille, etc. Ann. sci. nat. (2) 



1836. 5: 69-80, 1 colored pi. (life history) 

 Nunney, W. H. Development of the alder fly. Science gossip, n. s. 1895 



2 : 257-58. 

 Miall, L. C. The alder fly. Natural history of aquatic insects, p. 273-8, 1895. 



Larva (PI. 29, fig. 3) Measures in length 22 mm, including a 

 tail 4 mm long ; width 2.3 mm. Head and thorax of equal width, 

 abdomen very slowly tapering. 



Color yellowish, darker on the abdomen; a middorsal line of brown 

 extending from the middle of the head to the base of the abdomen, in- 

 terrupted on the middle of the prothorax ; an arrow-shaped mark on the 

 frons, and a brown line extending obHquely inward from the hind angles 

 of the head. Sides of thorax mottled with yellow and brown. Abdomen 

 brownish or purplish with paler sutures and a pair of submedian, dorsal 

 ( )-marks on the middle abdominal segments. 



Head depressed, subquadrangular, with rounded angles, and pro- 

 jecting mouth parts; prothorax subquadrangular, as large as the head, 

 and about as large as the two succeeding segments of the thorax taken 

 together. 



Abdominal segments 4-7 of about equal length, 3, 2 and i, succes- 

 sively, each a little shorter; segment 9 a little shorter than 8; 10 drawn 

 out into the tapering, lashlike filament 4 mm long; the filament marked 

 with black at two thirds its length and laterally fringed with yellowish 



