INFLUENCE OF WATER CURRENT ON CASE WEIGHT IN LARVAE OF THE CADDISFLY,GOERA CALCARATABANKS

Abstract

The larvae of certain Trichoptera are known to fashion into their cases structures to which a “ballast” function has been ascribed (Stuck, 1900; Buchner, 1905; Rousseau, 1921; Lloyd. 1921; Needham and Lloyd, 1937). Of forms living in the Ithaca, New York, region the cases ofStenophylax scabripennis, Halesus guttifer, Neophylax, andGoera calcarataare offered as examples. The term “ballast” has been used to imply a balancing as well as a weighting purpose depending upon the particular species under discussion. Rousseau (1921) in describing the general types of caddis cases says “…. in the absence of current, they (the cases) do not in general offer such adaptations as those which we find in the larvae living in moving water.