In our Himalayan streams

S. L. Hora, «Animal Life in torrential Stream», Journal of the Bombay Natural History Society, Madras, The Diocesan Press, vol. 32, parts 1 & 2, 1928, p. 118-119

The larvae of the Trichopterae or the so-called caddis-worms are found in all sort of inland waters. They build a shelter for themselves and drag it along wherever they go.

The case or shelter is held fast by the two very powerful, hooked claws at the hinder end. Several of them are found in rapid waters where they have devised several interesting ways to withstand the rush of water. Some  fasten theircases to rocks in swift currents by means of their salivary secretion in such a way that a stream-line form is presented to the current and the animal lives with the open end of the case up-stream. The case itself is greatly flattened on the under surface to come in close contact with the support.

Some weave a sort of a conical web on the rocks or on water plants growing in swift currents and themselves sitcomfortable in its pointed portion and wait for any booty  that the current may bring into their web. I have observed certain others that live on the under side of rocks in swift water forming a barricade of small stones and spinning a web over it with a hole for the animal to come out through.

Most remarkable among these worms are those in which thecase has taken a limpet-like form and the animal in thus enabled to cling fast in very rapid waters.

They occur in swift streams chiefly on the underside of stones and are know to be especially abundant in the rapids of Niagara, but are by no means uncommon in our Himalayan streams from Darjeeling to the Kangra valley and in the Khasi Hills.