How to Protect Tomato Plants from Hornworms

Protect tomato plants from hornworms by inspecting plants daily, hand-picking visible caterpillars, encouraging beneficial wasps, and using organic sprays like Bt when needed.

  1. Spot the Striped Invaders Early. Check your tomato plants every morning and evening during growing season. Look for large green caterpillars with white diagonal stripes and a horn-like projection on their rear end. Also watch for dark green or black droppings on leaves and soil, which indicate hornworm presence even when you can't see the pest itself.
  2. Grab and Go. Remove hornworms by hand when you spot them. Wear gloves if preferred, though hornworms don't bite or sting. Drop them into a bucket of soapy water or relocate them far from your garden. Check both the top and underside of leaves, as hornworms blend in extremely well with foliage.
  3. Let Wasps Work for You. Plant flowers like dill, fennel, marigolds, and zinnias near your tomatoes to attract beneficial parasitic wasps. These tiny wasps lay eggs on hornworms, creating white cocoons that eventually kill the pest. If you find a hornworm covered in white rice-like cocoons, leave it alone - the wasps are doing your work for you.
  4. Hit Them Small with Organic Spray. Spray organic Bt solution on tomato foliage when hornworms are small and most vulnerable. Mix according to package directions and apply in early evening to avoid harming beneficial insects. Reapply after rain or every 7-10 days during peak hornworm season. Focus on the undersides of leaves where young caterpillars feed.
  5. Block Moths Before They Land. Cover young tomato plants with floating row covers until they begin flowering to prevent adult hornworm moths from laying eggs. Remove covers when plants start blooming so pollinators can access flowers. This method works best as prevention rather than treatment.
  6. Disrupt Their Underground Cycle. Remove plant debris, fallen tomatoes, and weeds around your tomato plants regularly. Clean up garden beds completely at season end and till soil to disrupt hornworm pupae overwintering underground. Rotate tomato plantings to different garden areas each year when possible.