The influence of substrate on the functional response of Plectrocnemia conspersa (Curtis) larvae (Trichoptera:...

1. Experiments were carried out on the effects of substrate type on the functional response of Plectrocnemia conspersa Curtis for two of its naturally occurring prey species. 2. For both prey species predation rate is depressed on substrates which correspond to those favoured by the prey in the field. 3. The difference between predation rate on simple and on certain more complex substrates is due to the provision of refuges for prey on the latter types. 4. Differences in predation rate on the two prey species are due to their different behaviour when caught in the predators net. 5. The influence of substrate on the functional response of P. conspersa is discussed in the context of the stability of predator-prey interactions and the availability of prey to predators.