1. Egg-batch distribution in the Cinnabar Moth is related to plant size. The number of eggs per batch, however, is independent of size and other characteristics of the plant. 2. The adult behaviour of laying eggs in larger batches and the behaviour of young larvae to live gregariously leads to a higher survival. 3. The dispersal behaviour of larvae may have a positive influence on larval and pupal survival, and on adult fecundity, since the negative influences of high density, starvation and sub-optimal food are avoided. 4. Suggestions are given about the mechanism that underlies dispersal behaviour. 5. Dispersal is discussed in relation tot the aposomatic characteristics of the larvae.