What Kind Of Worms Eat Tomato Plants? (These Ruin Gardens!)


There is nothing more frustrating than seeing worms on your tomato plants after you careful cultivation of your garden.  Unfortunately, there are many different types of worms that feed on tomato plants.

So, what kind of worms eat tomato plants?  Tomato hornworms, armyworms, cutworms, and loopers are all different types of worms that eat tomato plants.  They may feed on the leaves, stems, flowers, and fruit of the tomato plant.

Let’s talk about the different types of worms that eat tomato plants and the life cycle of these worms.  This will give us some hints on how to prevent or destroy them in the future.

What Kind of Worms Eat Tomato Plants?

The “worms” on your tomato plants are actually caterpillars, or the larval stage of moths.  These larvae are often brown or green, and will feed on the leaves and other parts of your tomato plants.

The green worms can blend in easily with the leaves on your tomato plants, giving them excellent camouflage.  This means and you may lose an entire plant’s worth of leaves in one night if there are enough worms feeding!

There are some differences between the types of worms that you will see on your tomato plants, so let’s make the distinctions.

Types Of Worms That Eat Tomato Plants

Here are a few of the types of worms that eat tomato plants, along with a description of their appearance and activities.

Hornworm

There are two distinct varieties of tomato hornworms: tomato hornworms and tobacco hornworms.  Both are bright green worms with long horns coming out of the back side.  Both can feed on tomatoes, tobacco, and other nightshade plants such as peppers, eggplants, and potatoes.

Tomato hornworms have chevron stripes and a black horn on the back of the body.  They are the larvae of the five-spotted hawkmoth.  For more information, check out this article on the five-spotted hawkmoth on Wikipedia.

You can also read this article on tomato hornworms from the University of Minnesota Extension.

tomato hornworm
Hornworms can do lots of damage to tomato leaves in a short time!

On the other hand, tobacco hornworms have diagonal stripes and a red horn on the back of the body.  They are the larvae of the Carolina sphinx moth (also called the tobacco hawk moth).  For more information, check out this article on the Carolina sphinx moth on Wikipedia.

In the spring, the moths of both species lay eggs on the bottom side of leaves, such as those on tomato plants.  Later in the spring, the eggs hatch and larvae emerge.

The larvae then feed on leaves, eating the flesh and leaving the veins behind.  If they survive the growing season, they spend the winter in the soil in cocoons.

Finally, moths emerge from the cocoons to lay eggs on the leaves of new plants, thus repeating the cycle.

Wasps will often parasitize hornworms by laying eggs on their backs.  When the wasp eggs hatch, they eat the hornworm from the inside out, and grow into mature wasps.

Armyworm

There are many types of armyworms, which are the larval stage of armyworm moths.  Armyworms cause destruction to a variety of crops, including tomatoes.  Armyworm larvae will sometimes practice cannibalism, eating other worms of the same species.

Usually, armyworm outbreaks occur in early summer, with most damage done in late summer.  Fall armyworms are brown or gray, and males have a white spot on each wing.  Females lay eggs on the undersides of leaves, much like hornworms.

southern armyworm larva
This is the larva of a southern armyworm.

They exist in North America and South America, and recently invaded Africa.  For more information, check out this article from Wikipedia on armyworms.

southern armyworm
The larva pictured above will mature into the southern armyworm moth shown here.

You can also read this article on armyworms from the University of Illinois Extension.

Cutworm

Cutworms are the larvae of moths such as the turnip moth or large yellow underwing.  They can be green, brown, gray, or yellow.

cutworm eggs
Cutworms start off as eggs, shown here.

A cutworm will crawl along in your garden until it finds a plant to attack.  They will chew on leaves, buds, and stems.

The most damaging attack is at the stem of the plant.  The cutworm will chew around the stem and eventually cut down the plant, causing it to fall over.

cutworm
Cutworms eggs hatch into a cutworm larva, shown here. They often curl up when disturbed.

Some cutworms feed on a plant once they have cut it down, but others move on to attack additional plants.  You may know this from experience if they have ever seen an entire row of plants cut down in one night.

Cutworm moths will lay their eggs in organic material in soil, such as compost or mulch.  For more information, check out this article on cutworms from Wikipedia.

You can also read this article on cutworms from the University of Minnesota Extension.

If you want to find ways to deal with the problem of cutworms, check out my article on how to get rid of cutworms.

Looper

The cabbage looper is a caterpillar of the owlet moth.  It favors cruciferous vegetables such as broccoli and cabbage, but it can also affect beans, celery, lettuce, spinach, and tomatoes.  The larva arches its back into a loop as it crawls, giving it the name of looper.

cabbage looper
The cabbage looper prefers broccoli, cauliflower, and cabbage, but it will eat tomatoes as well.

The moths usually lay their eggs on the underside of leaves, often on higher and larger leaves on the plant.  A single moth can lay one thousand or more eggs in a day.  For more information, check out this article on the cabbage looper from Wikipedia.

You can also read this article on the cabbage looper from the University of Massachusetts at Amherst.

What Part Of The Tomato Plant Do Worms Eat?

As mentioned above, some worms will eat all parts of a tomato plant, including leaves, stems, flowers, and fruit.  A severe infestation of worms on a tomato plant can lead to defoliation (loss of most or all leaves) in a single night!

tomato plants
Worms will eat the leaves of tomato plants, but they may also go for the stems, flowers, and fruit as well.

Cutworms can destroy an entire plant, or multiple plants, without eating much of anything.  Some of them will chew around the stem at the base of a plant and continue on to another plant after knocking one down.

Some worms also attack other plants in the nightshade family, such as peppers, eggplant, and potatoes.  For this reason, it is a good idea to plant your tomatoes, peppers, eggplants, and potatoes in different parts of the garden.

jalapeno pepper plant
Watch out – many worms will attack your pepper plants as well!

It may not stop worms from moving around, but it will at least make things a little more difficult for them.  The more time they have to spend out in the open crawling between plants, the more time birds and other predators have to pick them off!

How To Get Rid Of Tomato Worms

Luckily, there are lots of ways to get rid of tomato worms.  Some involve a little more work than others, and some involve welcoming guests to your garden to help you with the problem.

Sprinkle Your Plants With Diatomaceous Earth

Diatomaceous earth is a white powder that is often sold at garden centers.  It is harmless to humans to handle, but if you looked at it under a microscope, it would look “sharp”, and indeed it is.

When insects crawl over diatomaceous earth or come into contact with it, the sharp pieces cut holes in their bodies.  They will then die of their injuries or due to dehydration.

diatomaceous earth
Diatomaceous earth is sharp enough to cut bugs open on contact.

Just remember that diatomaceous earth does not discriminate – it will also kill good insects.   If you decide to use it on your plants, you may end up hurting bees or other pollinators.  However, if you already hand pollinate due to a lack of bees, you may not mind using it.

When using diatomaceous earth, wear a mask to avoid breathing it in, since it can irritate your lungs just like any other fine powder.

Spray Your Plants With Neem Oil

Neem oil has a harsh odor and kills or repels common garden pests like aphids, snails, flies, and of course, worms.  The idea is to either kill the worms or to make the taste of the plant so unappealing that they will leave in search of greener pastures and tastier food.

As with diatomaceous earth, be sure to wear a mask to avoid breathing it in.  Also, wash it off if you get it on your hands, and avoid spraying plants that are already fruiting.

Order Some Ladybugs

Ladybugs are a beneficial insect in your garden.  In addition to eating pests like aphids, ladybugs will also eat the eggs or young larva (worms) of moths.

ladybug
Ladybugs will eat the eggs and small larva of some moth species.

You can order them online and release them into your garden, or just let them do their thing if they already exist in your yard.

Let The Wasps Be

If you have wasps in your yard or around your house, you might want to think twice before spraying them or calling pest control.  Wasps will often parasitize worms with their eggs, laying dozens on a single moth larva.

When the eggs hatch, they will eat the worm from the inside out, breeding more wasps to help take care of other worms.

wasp
Wasps will parasitize many worms with their eggs.

Make Birds Feel Welcome In Your Yard

Some birds also love to eat worms, so making a hospitable environment for birds can help to take care of worms.  Put in a birdbath and some birdhouses, and hopefully soon you will get some new residents that will help take care of insect pests.

cardinal
Make the birds feel welcome and they might help to get rid of the worms in your garden!

Some birds may also eat from your plants, especially berries.  However, the tradeoff may be worthwhile if you have a severe worm infestation on your hands.

Till The Soil Before Planting

Many species of moths spend the winter in the soil, in a compost pile, or in mulch.  If you till your soil or stir up your compost pile, you are likely to disturb the life cycle of the moths by damaging them in their winter hibernation state.

front tine tiller
Tilling your soil before planting can disturb and kill moths in the spring.

Just be careful about tilling the soil if you have lots of earthworms, which are beneficial to your garden and will be disturbed by tilling. For more information, check out my article on the cost of rototilling.

Practice Crop Rotation

Using crop rotation is one way to prevent infestations of worms in your garden.  Since many worms often attack many members of the nightshade family, it helps to avoid planting any nightshade plants in the same place year after year.

Instead, rotate your crops in alternating two, three, or four year patterns.

Pick Worms Off Of Your Tomato Plants By Hand

As a last resort, you can go out and pick worms off of your tomato plants by hand to stop them from feeding.  You may have to do this at night, since some worms, such as the cutworm, feed nocturnally.  You can put the worms in soapy water or crush them to kill them.

Conclusion

By now, you know some of the more common worms that may be attacking your tomato plants.  You also have an idea of how to fight or prevent them in the future.

I hope you found this article helpful – if so, please share it with someone who can use the information.  If you have any questions or advice about worms, caterpillars, or moths in the garden, please leave a comment below.

jonathon.david.madore

Hi, I'm Jon. Let's solve your gardening problems, spend more time growing, and get the best harvest every year!

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