Experiments on predation and substratum choice by larvae of the muscid fly, Limnophora riparia

Larvae of the muscid fly Limnophora riparia live in lake outlets and prey on other invertebrates living there. In experiments, we demonstrated that larvae prefer moss as a substratum, though they will bury themselves in any suitable material to avoid light. The substratum is used to anchor Limnophora larvae as they attack their prey. When given a choice of prey they preferred chironomid and black fly larvae to oligochaetes and psyehodid larvae. Larvae of the black fly Simulium noelleri were used in laboratory experiments to test the interaction of predator and prey. Limnophora larvae attacked black fly larvae of all sizes, but preferred small larvae, the body contents of which were often removed completely. Increasing prey or predator density did not affect this latter preference, though an increase in predator density, or a decrease in prey density, did cause the predator to take prey of medium size as well as small prey. Limnophora larvae showed the same size preference when attacking dead (freshly‐killed) prey and they preferred to attack larvae rather than pupae when both were available. They did not attack black fly eggs.