Hornworms
Identification
Adult hornworms are large, nocturnal moths with brown/gray wings. Hornworm caterpillars are green with white stripes or Vs on the side of their body and a soft horn or spike protruding from their posterior.
Damage
Tobacco and tomato hornworms leave dark pellets of excrement behind. Damage is eaten leaves, often toward the top of the plants. The caterpillars feed at night and shelter in the foliage during the day.
Prevention
Plant lots of flowering herbs with tiny flowers near susceptible plants as these flowers attract tiny parasitic cotesia wasps that use hornworms as hosts for their young, eventually bringing death to the hornworm (more on using beneficial insects to control pests in a bit). This is a great way to prevent all of the pests discussed in this guide to vegetable garden pests.
Physical control
Inspect plants for hornworms on a regular basis and handpick, but do not destroy any hornworms that have the white, rice-like cocoons of parasitic wasps hanging from their backs.
Chemical control
Spray products are seldom necessary as handpicking is more successful. If necessary, Bacillus thuringiensis Kurstaki strain (Btk) and spinosad-based products can be effective. Check local regulations (or your local Extension Office where applicable) to identify which products can be used in home gardens in your area. Follow label instructions carefully for safe and effective insecticide application and to ensure that edible crops are safe to harvest. Test insecticide on a few plants before widespread application. Look for the most selective insecticide to minimize harm to beneficial insects- even some “selective” and "natural" insecticides can still negatively impact beneficial insects. Apply contact-based insecticides in the late evening and try to avoid spraying during blooming to minimize negative impacts on pollinators- in some cases the insecticide may need to be hosed off in the morning to avoid contact with pollinators. Do not spray spinosad on flowering plants.
Plants Affected
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