Two Techniques for Monitoring Feeding of Large Larval Lepidoptera, with Notes on Feeding Rhythms of Late-instar Gypsy Moths (Lepidoptera: Lymantriidae)1

Abstract

An inexpensive, totally mechanical device was used for monitoring feeding of late-instar larvae of the gypsy moth, Lymantria dispar (L.). A two-lever system transmits feeding motions from a freely suspended piece of artificial diet to a pen nib that writes on a rotating hygrothermograph drum. This device is suitable for monitoring feeding when a fine-grained description of feeding behavior is unnecessary. When larvae were placed into monitors and exposed to 16:8 (L:D) photoperiod, feeding occurred primarily during scotophase. Under continuous scotophase, rhythmicity of feeding was reduced but detectable throughout a 3-day test; under continuous light, feeding became essentially arrhythmic within 24 h. To monitor feeding on foliage, the electronic feeding detector of Kogan (1973) was adapted to the gypsy moth.