1914] Biology of Net-Spinning Trichoptera 261 
These writers believe that the imago probably lays her eggs 
in loose, web-like masses which are doubtless a conglomeration 
of old nets and that the young larve live together in them for a 
long time. 
Plectrocnemia. 
Miall (1895) gives a description of a Plectrocnemia net 
written by Mr. T. H. Taylor. ‘‘Plectrocnemia finds its home 
in streams where the water flows swiftly over a stony bed. Ifa 
stone be lifted out, the under side is often found to be covered 
with patches of mud from which brown larve emerge and begin 
to crawl over the surface. The muddy particles are evidently 
held together by some binding substance, and the whole forms 
the retreat of the Caddis-worms, corresponding to the cases of 
Phryganea. When a larva is placed in a vessel of clear water, 
it at once begins to explore its new quarters, and eventually 
selects a site for its dwelling. This is made of silken threads 
secreted by the large silk glands, and when completed the 
structure consists of a tube considerably longer and broader 
than its occupant and open at both ends. It is supported and 
strengthened by a meshwork of silken threads, which spread 
out for a considerable distance, and are attached to the sur- 
rounding objects. 
From time to time the larva turns round in its case and 
even leaves it for a short space. Generally, however, it re- 
mains quiet inside, apparently on the alert for prey. If a. 
Chironomus or other small aquatic larva approaches, it is 
almost certain to get entangled in the network of silken threads. 
At once the Caddis-worm in its retreat perceives the presence 
of a possible victim. The long hairs which cover the body are 
possibly tactile, and receive slight disturbances of the silken 
network. The Plectrocnemia then proceeds warily to de- 
termine the cause of the disturbance. Should the Chironomus 
be entangled near the middle of the tube, the Caddis-worm does 
not hesitate to bite its way through the side, and its jaws very 
soon quiet the struggles of the prey. 
There is some resemblance between the snare of the Plec- 
trocnemia and the web of a spider, but the Plectrocnemia is 
effectually concealed by the mud which clings to its retreat.”’ 
The net of Plectrocnemia conspersa Curt. is described by 
Wesenberg-Lund (1911). The larve—at least from April until 
