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Bug Watch: Tomato and Tobacco Hornworms

A Tobacco Hornworm (Manduca sexta)

  • Red Horn
  • Black margins to white stripes

Tobacco hornworm - black margins to white strips with a red horn

Tomato Hornworm (Manduca quinquemaculata)

  • Blue Horn
  • Green margins to white stripes
Tomato horn worm - white stripes, green caterpillar, blue horn

Hornworms: a garden pest

Both tobacco and tomato hornworms are garden pests for members of the Solanaceae family, which includes tomatoes and tobacco. They will voraciously eat the leaves and the fruit of these plants and can become a major problem if left unchecked. My personal experience with these guys is a credit to nature and affirmation to my no-spray mentality (which has sometimes led to major crop loss while I let nature address the imbalance). In this case nature responded swiftly and effectively and I’ve never had a hornworm problem.

The first hornworm I found in my new garden, I fed to the ducks. I was pretty amazed they would eat something so big and with a red horn to boot. The second hornworm I found, just days later, I left the caterpillar to it’s demise and a few had tiny white rice-like pods growing from it’s back. These were the egg sacks of a parasitic wasp (most likely a Braconid wasp).

Tomato Hornworm being paracitized by braconid wasp

I left the caterpillar to it’s demise and a few weeks later I found the mummified remains. To this day I have never found more than a couple of hornworms and I always leave them be, as food for the wasps.

Tabacco Hornworm decimated by the parasitic braconid wasp

Hornworm Solutions

I realize that not everyone will have the luck I stumbled upon, and that horn worms can devastate a garden crop.

  • Identification and removal by hand is an effective control. These guys are big and fairly easy to see. If they persist with evasive camouflage, I have read that a UV light at night will cause them to show up as a different color to the leaves, making handpicking quick and easy.
  • Companion planting with marigolds is said to be an effective solution. I have always planted marigolds with my tomatoes and perhaps this could be another reason why I haven’t had major issues with this pest.
  • Lacewings, Yellow Jackets and Ladybugs will eat the eggs and young caterpillars, so continue to encourage these beneficial insects into your garden.

Here is a pretty awesome video to tell the difference between the Tomato Hornworm and the Tobacco Hornworm

Want to share your garden wisdom? Comment below and we’ll grow wise together!

 Written by Chris Smith

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