Prey Size and Feeding Patterns in Dinocras cephalotes (Plecoptera)

Abstract
In laboratory experiments, nymphs of the predatory stonefly D. cephalotes (Curtis), supplied with large individuals of the prey Baetis rhodani (Pict.), emerged earlier than nymphs fed with small individuals of the mayfly. Early emergence, within certain limits, may be advantageous to the stonefly. The stonefly nymphs did not select prey of the most favorable size, probably because of their hunting technique. Small predators were able to kill large prey, but frequently left heavily sclerotized parts of large mayfly nymphs. During the last instar, feeding was initially low but increased to a maximum after a few days. Feeding therafter decreased slowly and almost ceased several days before emergence. A similar pattern, although not so expressed was noted in earlier instars. Generally, food intake was pulsed with maxima every 2.5-4 day.