University of Illinois Extension
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Hornworm - Tomato


They overwinter as pupa in the soil and become more active in July. The adult is a large moth, which lay pale green eggs on the underside of the leaves. The larvae are green with eight white stripes and have a horn on their tail end. The larvae feed on both leaves and fruits. Tomato hornworm are heavy feeders and 1-2 worms can defoliate a five-foot tomato plant in less than three days. The larva drops off the plant after completing the feeding and pupates in the soil.


Predatory bugs and parasitic wasps do attack the larvae (Look for white cocoons on the body of the hornworm - do NOT kill the parasitized hornworm as that also reduces the number of future predators on the hornworm.), and helps keep hornworm populations under control. For none parasitized larva, physically remove the larva from the leaves, and farmers should also monitor the moth using blacklight trap and spray with insecticides recommended in your state.