A rhythm underlying feeding behaviour in a highly polyphagous caterpillar

Behavioural mechanisms of food mixing were studied in the polyphagous cater pillar Grammia geneura (Strecker) (Lepidoptera, Arctiidae) in arenas with d ifferent plant foods. Combinations of food plants, including single and mul tiple plant species were used. Behavioural observations on individuals of s imilar age were undertaken for 4 h. Foraging and feeding behaviour were mon itored in detail. It was found that feeding was generally initiated during short intervals that represented the peaks of an endogenous activity rhythm . Feeding was not initiated on all peaks but at times that represented mult iples of the oscillatory period. The oscillation fitted to each individual varied between 10 and 13 min. The possible significance of the oscillation is discussed.