Abstract
Newly hatched nymphs of the German cockroach, Blattella germanica (L.) were reared in isolation and groups of two individuals until adult emergence. Growth was accelerated when the nymphs were reared in groups of two, but not accelerated when their antennae were amputated withoiut regard to being kept in isolation or in groups. The nymph reared in a pair with an antennectomized nymph did not show accelerated growth but showed almost the same growth pattern as the isolated one. These results suggest that the tactile stimuli transmitted through the antennae is responsible for the perception of the other individual. It seems likely that bristles distributed on the antennae play the important role dof receptor of tactile stimuli, and that touch and vibration of the antennae are considered to be the most certain communication method between two individuals.
