Feeding Rhythms of Gypsy Moth Larvae: Effect of Food Quality During Outbreaks

At outbreak population levels, late—instar gypsy moth larvae abandon their strictly nocturnal feeding habit and eat intermittently throughout the day and night. In laboratory studies, an increased tendency to feed during the day was induced by rearing larvae either on leaves of heavily defoliated red oaks or on artificial diets that contained tannin. The well—documented but poorly understood shift in feeding rhythms has been viewed as an adaptation to enhance survival during outbreaks; it now appears to be mediated by defoliation—induced changes in leaf quality.