The adjustment of the specific

Anonyme, « British Insects and Butterflies, may and june », The Illustrated London Almanach for 1860, Londres, 1860.

The aquatic larvae of the phryganeae being called bankbait. The caddis-worm make for themselves curious habitations, which snaillike they drag about with them as they crawl along the sandy bottom of streams or rivers. These habitations are tubular, so as to fit the body of the larva ; and each species has its own selection un the choice of materials. Some glue particles of wood together, intermixed with gravel, and thus make a rough case ; some use portions of the slender stems of rushes, and form a fluted cylinder; some agglutinate grains and sand together, and form a smooth and sightly domicile; others avail themselves of fragments of river-shells, intermixed with smakk pebbles, making a fanciful grotto-like tenement smothly lined with silk. In clear shallow water these larvae may be observed with the head and thorax protuded crawling about the quest of food. We have seen numbers surround a crushed snail, purposely thrown in amongst them, and commence with cagerness to devour it. These caddis-worms are very careful as to the adjustment of the specific gravity of their case; it must not incumber them, but it must be submerged. Often therefore, any alterations made, and with that precision which is the result of unerring instinct.