101 



ring. Larvae with three pairs of jointed legs, and a distinct head 

 with biting mouth-parts. Pupa inactive, but a1)le to creep out of 

 the water, or to swim rapidly to the surface when ready to yield 

 the winged adult. 



LarvfB of this group usiially construct movable or fixed cases 

 with openings at the ends. These cases are sometimes of 

 peculiar shape, and oftener attract attention than tlie winged in- 

 sects. They may be cylindrical, cone shaped, spiral, like a flat- 

 tened ink bottle, etc., and generally have bits of vegetation, or 

 sand, fastened over the outer surface. The adults are small, ob- 

 scurely-colored insects, which usually take no food, and after de- 

 positing their eggs soon die. The eggs, enclosed in a gelatinous 

 material, are placed on aquatic plants, the females, it is thought, 

 sometimes descending into the water for this purpose. The larva; 

 feed on vegetable matter, such as dead leaves, stems, and wood, but 

 sometimes devour also small insects and crustaceans. Those I have ex- 

 amined are abundant in small streams in Central Illinois, and make 

 large cylindrical cases, to the outside of which are fastened longitudi- 

 nally, numerous small sticks. The alimentary canal of this lar^a 

 has always been found filled with decayed woody vegetable mat- 

 ter. The pupae are formed in the cases which are, if movable, 

 fastened down by the larva previous to pupation. 



Trichoptera, larva (1). 



The common case-fly larva at Quincy was a somewhat unusual 

 one as to habits. Most of our species creep slowly about on veg- 

 etation or on the bottom. This one is a free-swimming larva and 

 one or two were always taken when the surface net was drawn 

 over the deepest water of Quincy Bay. It was captured on one occa- 

 sion in the swift current of the river in a net drawn after the steamer 

 "Hannibal Eagle". The case is trumpet-shaped, gradually decreas- 

 ing in caliber from the larger end (which has a diameter of about 

 .07 inch) to the smaller extremity, where the diameter is about .03 

 inch. The outside of the case has scattered bits of dead vegeta- 

 ble matter fastened over it, and numerous minute particles of sand. 

 Fastened to one side, sometimes to two sides, is a long rootlet or 

 twig of a weed that may project at one or both extremities some 

 distance beyond the case. The larva is plain white, with the head 

 mottled with yellow and deep brown. Along the sides are at- 

 tached fleshy respiratory filaments. The usual tubercles and hooks 

 for adhering to the case are present. It swims by striking the 

 water with the very long and heavily fringed hind legs, these 

 being projected beyond the large opening for this purpose. 



Trichoptera, larva (2). 



A second larva lives in a short, conical case about .25 inch long, 

 with a diameter of .125 inch at the larger and of .06 inch at the 

 smaller end. The outer surface is thickly covered with bits of 

 dead vegetation, but lacks the long pieces which seem never to be 

 absent from the other cases. The larva also is short and stout, 



