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How to Rid Your Garden of Tomato Hornworms

Updated on June 13, 2017
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Caren White is a Master Gardener and longtime volunteer at Rutgers Gardens as well as an instructor at Home Gardeners School.

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When I was a child, I was not afraid of insects and snakes. It was not uncommon for me to capture specimens and bring them home with the intention of keeping them as pets. In an effort to keep me from bringing home tomato hornworms, my father told me not to touch them because they would sting me, pointing out the large stinger on the rear of their bodies. That stinger looked huge and terrified me. I gave tomato hornworms a wide berth after that.

Sphinx moth, also called a hummingbird moth
Sphinx moth, also called a hummingbird moth | Source

Know Your Enemy

The tomato hornworm is probably the largest caterpillar that you will find in your vegetable garden, measuring as large as 5 inches long. They are green with markings in white and black and sport a horn on the rear of their bodies. They do not sting, however.

Tomato hornworms are the larval stage of the sphinx moth, commonly referred to as the hummingbird moth because of its resemblance to hummingbirds both in body type and how they fly and sip nectar from flowers. The moths pupate in the soil over the winter, emerging in the spring to lay their eggs on your solanaceous plants, including tomatoes, eggplants, peppers and potatoes. They eggs hatch within 5 days and the resulting larvae, the tomato hornworms, then spend the next 4 to 6 weeks gorging themselves on the foliage of your solanaceous plants before they burrow into the soil and spend the winter inside of a cocoon. In warmer climates, the larvae will stay in the soil for 2 to 3 weeks creating the possibility of a second generation during the growing season.

Pick Your Own

Damage from the tomato hornworm is easy to spot, however finding the larvae themselves is a little more difficult because their coloring and markings act as an excellent camouflage. Look for their green droppings in the tops of the leaves. The hornworms will be on the bottoms of the leaves. Then you can simply pick them off the leaves (remember they don't sting despite the scary horn) and either squish them or if you are squeamish, drop them into a bucket of soapy water.

Companion Planting

You can prevent the moths from laying their eggs on your plants by interplanting dill or borage amongst your solanaceous crops. The moths don't like them, and will fly off to your neighbor's garden to lay their eggs.

Parasitized hornworm aka Dead Man Walking
Parasitized hornworm aka Dead Man Walking | Source

The Enemy of My Enemy Is My Friend

Beneficial insects are a big help in controlling pests in your garden. Attract them with flowers and herbs that have tiny blossoms. Brachnid wasps will reward you by laying their eggs on the tomato hornworms they find on your plants. Those eggs will hatch and the larvae will feed on the hornworm, killing it. If you see a tomato hornworm sporting what looks like grains of rice, leave him alone. The "rice" is actually the eggs of the brachnid wasp and that hornworm is a "dead man walking".

Till Twice

A deep tilling in the fall and then again in the spring will kill up to 90% of the pupating larvae in your garden. That means many fewer moths laying eggs in the spring.

© 2014 Caren White

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    • OldRoses profile image
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      Caren White 3 years ago from Franklin Park, NJ

      The moths are incredible. They're huge. Thank you for reading and commenting.

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      Jim 3 years ago from Kansas

      I have had them a few times, but not often. Nice information to know.

    • OldRoses profile image
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      Caren White 3 years ago from Franklin Park, NJ

      Silva, I hate the "squish" too! Did your granddaughters' pets make cocoons and turn into moths? I always loved watching caterpillars do that when I was a child. Thanks for reading and commenting.

    • Silva Hayes profile image

      Silva Hayes 3 years ago from Spicewood, Texas

      Lovely hub, very useful. One year we had many of these worms on our tomato plants. My two tender-hearted granddaughters thought the worms were adorable and wanted to keep them as pets. We picked them off and kept them in large plastic jars with holes in the lids and twigs for them to eat. I remember when I was a child, my mother would instruct me to pick them off and step on them and I just couldn't stand the "squish."

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      ElleBee 3 years ago

      I have the space for a compost bin, just not the need since I don't have enough plants. :) And I totally agree on worms in the kitchen!

    • OldRoses profile image
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      Caren White 3 years ago from Franklin Park, NJ

      Have you considered vermicomposting (worms)? It's popular in New York City because everyone lives in apartments and vermicomposters are kept indoors. Personally, I am grossed out by the thought of worms in my kitchen, but apparently there are quite a few people who are not as squeamish as I am.

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      ElleBee 3 years ago

      I don't compost since I have no "Real" garden, just container tomatoes, so they got half a banana peel each when they were potted. Definitely looking forward to my own house with a nice yard, big garden, and a compost bin in the future.

    • OldRoses profile image
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      Caren White 3 years ago from Franklin Park, NJ

      I LOVE banana peels for adding potassium to the soil! I'm always torn over whether I should place them directly into the garden or into my compost to enrich it. I don't understand why people spend so much money on chemical fertilizers when there are so many free alternatives like eggshells and banana peels. Throwing them in the garbage adds to the landfill problem. I live in NJ, a tiny state with a large population and a large landfill problem. Why not use your waste to enrich your soil instead? Sorry, I tend to rant a lot on this subject.

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      ElleBee 3 years ago

      Ah, it must have been for the slugs then. Not sure exactly what it was we had on our tomatoes, but we kept getting something! And yes, when I plant my tomatoes I now put crushed eggshells for calcium as well as a banana peel for potassium in the soil at planting.

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      Caren White 3 years ago from Franklin Park, NJ

      Elle, using a car to kill tomato hornworms has got to be the best way to kill hornworms that I have ever heard! Thanks so much for sharing that. Eggshells probably wouldn't be effective on them because they hatch from eggs that are laid directly on the plants. Spreading crushed eggshells around your plants works great to kill slugs and snails. And putting them in the hole before you plant your tomatoes, provides calcium and prevents blossom end rot. Thanks for reading and commenting.

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      ElleBee 3 years ago

      Yuck! Happy I didn't have them this year. Once when I was a child we got terrible ones that simply wouldn't die, we ended up putting them in a coffee can which was then both run over by the car and burned. My mom used to bury crushed up egg shells around the base of the plants to keep worms away - not sure how well it works, but I still put some in when I plant every year.

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      Caren White 3 years ago from Franklin Park, NJ

      Rochelle, I love both those methods! Feeding them to the chickens is a great way to recycle/reuse. I love throwing weeds into my composter because I am taking something I don't want/need (weeds) and making it into something I do want/need (compost). Feeding tomato hornworms to your chickens is the same thing - pests into food. Thanks for reading and commenting.

    • Rochelle Frank profile image

      Rochelle Frank 3 years ago from California Gold Country

      I don't like to squish them, they make such a disgusting squish. I remember my mom taking her garden shears, opening the blades wide, placing the blades on each side of the worm, then looking away when she snipped the worm in half.

      My favorite way to dispose of them is to break off the twig they are on and throw it into the chicken yard. The hens will fight over it, but when they are finished they are licking their lips and there's not a trace of the pest left.

    • OldRoses profile image
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      Caren White 3 years ago from Franklin Park, NJ

      You're welcome, Dolores! They are pretty scary to look at. Thanks for reading and commenting.

    • Dolores Monet profile image

      Dolores Monet 3 years ago from East Coast, United States

      I've seen these monsters once or twice, and being a baby, usually scream and run away. But when you look close, they are kind of pretty. Thanks for the advice!

    • OldRoses profile image
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      Caren White 3 years ago from Franklin Park, NJ

      Kaili you are so right! We need to be vigilant. Thanks for reading and voting.

    • Kaili Bisson profile image

      Kaili Bisson 3 years ago from Canada

      Nasty looking things. So many pests after our precious flowers and veggies this year. Voted up!

    • OldRoses profile image
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      Caren White 3 years ago from Franklin Park, NJ

      Flourish, they don't sting. They are just very scary looking. Thanks for reading and commenting.

    • FlourishAnyway profile image

      FlourishAnyway 3 years ago from USA

      Yuck! I have seen these but did not know they had a stinger. Definitely staying away. I don't have them on the few tomatoes I grow.