Deadly Tomato Horn Worm - And How To Find Them

“The worm appearing on it was an object of much terror, it being currently regarded as poisonous and importing a poisonous quality to the fruit if it should chance to crawl upon it.” -  The Illustrated Annual Register of Rural Affairs and Cultivator Almanac (1867) John J Thomas

Picture a large green caterpillar like creature with diagonal white stripes and a small red horn protruding from it. This caterpillar traveling, camouflaged, through a canopy of both ripe and unripe tomatoes of the highest quality. I’m talking prize winning tomatoes. Moving though the tomatoes, he becomes hungry and decides to snack on the first tomato he sees. After a few massive bites, the creature notices another tomato and decides that the one hanging a few feet away might taste better and begins to travel to his second meal. And on he goes, feasting throughout this tomato garden of eden.

The worm in question being the Tomato Horn Worm. No tomatoes or peppers are safe. And if left unchecked, he has the ability to consume all of the year’s harvest and ruin a gardener’s normally pleasant mood.

Historically many people thought these were poisonous. In fact, there was a great deal of time where people believed that tomatoes themselves were poisonous. I’ve seen stories where fear was spread because people were dying shortly after eating tomatoes. But it turned out it had more to do with the plates that the tomatoes were on, being lead, than the tomatoes themselves. The acidity of the tomatoes causing the lead to leach out and poison the person who was eating it. Like many stories, however, we have since found that tomatoes are not poisonous and neither are the horn worms that consume them.

Just the other day I ran into one of these villains and thought I’d share my experience as a warning to those who are growing any plants from the Nightshade family.

First off, this isn’t the first year I have had issue with Tomato Horn Worms. And I can still remember the first time I saw one. With all the colors on it and just the sheer size, you can’t help but think it is dangerous. As like me, my guess is you will run into signs of a horn worm before actually seeing the culprit himself. So what are these signs you might ask?

First, you will begin to notice your tomatoes with massive bites out of them. It will seem like a rabbit or some larger mammal has been helping themselves to your fruits.

If you notice damage on the tomatoes, search around for little brown pellets. This is their disposal of your fruits and it is alarmingly large for a caterpillar if you ask me. Granted, the Tomato Horn Worm I was fighting was about 3.5” long.

If both of the above have been identified, you can be sure that you have an intruder and should begin searching for him. I generally find them hiding in plain sight, as they blend in so well color wise. Check under leaves and along stems. They are generally lingering where most of the damage has been done.

Once you find the monster, simply put him in a cup of soap and water to dispose of him.

Now you may ask, “ how can i prevent them”? And my personal opinion on this one is to encourage beneficial insects (parasitic wasps) who will lay their eggs on the caterpillar and will devour him once hatched. This along with manual removal is best. I think the negative of insecticides outweigh the benefits in this case.

I am at a slight disadvantage in preventing this creature if I do not have the good insects in the garden yet because I do not till. If you till the soil after the season, it should uproot any buried caterpillar larvae and kill them. So for those of you that till, plus one point to you!

As of this moment, I have captured the current tomato destroyer, but will be keeping my eyes open for more hungry caterpillars. I hope you too, are now able to stop Tomato Horn Worms in their tracks.

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About the Author

Geoff has been growing plants and vegetables consistently for the last 6 years and actively experiments with, and writes about, all aspects of gardening.

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