LIMNOPHILID&. 
ASTENOPHYLAX ARGUS. 
Hasitat.—In most of the slow-moving, alder-bordered 
streams of the uplands the species is uncommon, but in Michigan 
Stream to the South, and Argus and Spherium Streams to the 
East, they occur in the greatest abundance. In Michigan Stream 
their numbers are astonishing for a species of such size. Many 
hundreds of individuals live on a single rod of the small creek’s 
bottom, and scores of pupz can often be found clinging to a 
single root or stick. 
Hasits.—As might be expected under the uniform conditions 
of the spring-fed upland streams, the larve alter their habits but 
little during the changing seasons. In winter, as in summer, they 
crawl actively over the bottom, feeding and carrying on their 
usual activities. In both seasons the stomachs are equally gorged. 
By the middle of April the larve have ceased their activities 
and have gathered and attached to their cases bulky, heavy mate- 
rial, large pebbles, chunks of bark, the large species of Spheriide, 
Spherium simile, or twigs, sometimes inhabited by the wood-bor- 
ing Trichoptera of the genus Ganonema. ‘These heavy cases are 
attached firmly by their cephalic ends to submerged logs, roots, or 
other solid supports. At this time the sieve-nets are spun. In 
Astenophylax argus the sieves are located within the tube a short 
distance from its caudal and cephalic ends. The mesh varies in 
size and form, but is roughly hexagonal. 
Foop oF THE Larvai—The food of the larva throughout the 
year consists of dead bark and wood rasped from submerged 
twigs and logs. Specimens collected in February contained the 
same kind of food as specimens collected in mid-summer, and 
at both seasons the alimentary tracts were equally gorged. 
Periop oF Emercinc.—The time of emerging is confined to 
the first two weeks of June. 
DEscRIPTION OF THE Larva.—Length of the mature larva is 
50 mm. Its breadth at the third thoracic segment is 6 mm. 
Head.—The head, except the mandibles, which are black, is 
brown, with inconspicuous darker markings, which vary some- 
what in intensity in different individuals, but maintain the same 
general pattern for the species; the color-pattern and distribution 
57 
