156 Journal New York Entomological Society. [Vol. xxvil. 



laria and Syncdra. This food they obtain by browsing on the stones 

 and vegetation over which they hastily scramble. At the end of the 

 third week the green algae (Edogonium, Cladophora, Ulothrix, Cylin- 

 drospermum, and bits of seed plants are added to the diet. 



At the end of the sixth week, the larva is about three-sixteenths 

 of an inch in length. It now possesses gills and a full armature of 

 spines on the legs, such as is shown for front and middle legs in 

 figures 5 and 7. The earlier condition of these same legs is shown 

 in figures 4 and 6 of the plate. The larvae now leave the quiet 

 eddies along the bank, and concentrate on the upper surface of the 

 current-swept boulders. There, with one edge of the front end of 

 their cases firmly cemented to the stones, they face the current. With 

 head thrust slightly forward, prothoracic legs extending straight 

 ahead, mesothoracic legs upward, and metathoracic legs at the sides 

 (figs. 1, 2), they wait for food. 



From a purely herbivorous diet obtained by active searching, they 

 now become mainly carnivorous, waiting in a most receptive attitude 

 for whatever may come within their powerful grasp. An examina- 

 tion of the stomach contents at this time reveals small quantities of 

 diatoms, slightly larger amounts of the algae and tissue of higher 

 plant and, by far the greatest in bulk, animal food such as May-fly 

 nymphs of the genus Heptagenia and Ephemerella, Hydrachnids, 

 Chironomid larva, small Crustacea, and even Brachycentras larvae. 

 Fig. 12 is a diagram of the alimentary tract of a larva collected the 

 latter part of September, when the predominance of animal food was 

 at its maximum. Compared with that of a younger larva five weeks 

 old (fig. 11), it shows the fore intestine enlarged and somewhat con- 

 stricted in the center. The mid intestine is shorter and narrower, 

 while the hind intestine is larger and relatively longer. 



The spinning glands are very well developed, even when the larva 

 leaves the egg mass. At the base of the labium the two glands join 

 into a common chitinized duct which forms the silk press. This 

 leads to an opening at the tip of the labium. 



In the laboratory, larval habits were best observed by using a 

 piece of thin glass tubing one-half inch in diameter. This was 

 heated and carefully flattened on the top to prevent aberration. In- 

 side the tube fine sand and small stones were attached to the bottom 

 by means of commercial glass cement. A cap of ordinary window 



