Observations on the Response of Adults of the European Corn Borer to Light in Egg Laying

Abstract

In its active stages as adult and larva the European corn borer ( Pyrausta nubilalis Hubn.) is, for the most part, a lover of darkness. As dusk approaches during the periods of the year when the moths are in the field, they become active, fly, mate and deposit eggs during the hours of darkness and as dawn approaches they become inactive and rest or hide on the under side of leaves or in other protected places, remaining quiet during the day to resume activity when darkness approaches again. The larva, because of its habit of feeding in tunnels within the host plant throughout development, except in some instances during the first and second instar, is also negatively phototropic. Any migration of the larvae that may take place or any movement of larvaeoutside of the burrow that may occur, happens principally at night, and while large numbers of larvaemay be found moving about outside their burrows at favorable times during the hours of darkness, they are seldom seen in daylight. On hatching from the egg, however, the young larvaefrequently wander about on the plant, feed on the epidermis of the leaves or bore into the leaves or midribs of leaves and feed for a time before entering the main stalk of corn or other food plant. This is especially the case in the spring when the food plants are small and even the main stalks frequently being too delicate to accommodate the larvae. They soon seek shelter, however, and bore into the main stem or other parts of the plants that offer protection. In some instances during studies of migration, the young larvaehave been found to be less susceptible to light than older larvae, a condition that is undoubtedly comparable to the activity of the newly hatched larvaein the habit of surface feeding before burying themselves within the tissues of the food plant.