120 THE CANADIAN ENTOMOLOGIST. 



Larval habits. — Within its case, with openings less than }/2 

 mm. in diameter, the larva, fig. 1, measuring three mm. in breadth 

 at its 5th abdominal segment, is held a prisoner, unable to move 

 from place to place or to escape. In the stream we were never 

 able to detect any activity on the part of the larvae, nor to see any 

 part of its protruding from its case. In the laboratory, however, 

 though the larvae remained concealed within their cases during the 

 day, they fed actively at night, protruding the long thorax and first 

 four abdominal segments from one opening of the case, swinging 

 them slowly from side to side while scraping the rqck with their 

 mandibles; then withdrawing into the case, only to appear and 

 repeat the procedure from the other end. 



When at rest in the case, the long neck-like thorax and ab- 

 dominal segments are looped back, reaching to about the caudal 

 extreme of the abdomen. 



Larval Food. — The stomachs examined contained the algae, 

 mostly diatoms, which form the ooze on the rocks where the larvae 

 live — Meridion, Gomphonema, Synedra, etc., and a few unde- 

 terminable fragments of Chlorophyceae. 



Pupal Habits. — In preparation for pupation the larva plugs 

 the openings of its case with thick, unperforated, silk, and between 

 itself and the rock spins a thin loose maze of silken threads. The 

 first pupaj appeared about the first of May, and by the 12th of 

 May almost all had pupated, though a few prepupa still remained. 

 On May 21st two adults emerged in captivity. When emerging 

 the pupa cuts a jagged, irregular hole in the top, near one end, of 

 the case through which it escapes. 



Description of Larva and Pupa. 



Larva. — Length 5 mm. Breadth of 3rd thoracic segment 3^ 

 mm., 5th and 6th abdominal segments 3 mm. each. Colour of 

 fleshy portions in life, brilliant bluish green, except the two swollen 

 segments, which are duller. The colour is apparently due to fat 

 within the body, which shows through the body-wall in irregular 

 masses, giving an uneven coloration when viewed through the 

 microscope. 



Head. — Heavily chitinized and uniformly dark brown, except 

 the labium and maxilla^ and an ill-defined ring around each eye, 

 which are lighter. The frons, as an area, shows rather distinctly 



