Where Does Tomato Hornworm Come From? And How To Get Rid Of Them!

When you see a hornworm on a tomato, do you ever stop to think about where it came from? How did they get into your garden, and why are they eating your perfectly good tomato plants? Do hornworms emerge from the soil, or do they develop from giant moths’ eggs? Read on and find out where do tomato hornworms come from and ho to control and prevent them!

where do tomato hornworms come from

Tomato Hornworms are the caterpillar of the large Sphynx moth (sometimes called hummingbird moth).

Well,  you are not alone! Gardeners around the world struggle to find answers to these questions. But don’t worry; we have got you covered!

Tomato hornworms hatch from the eggs of a beautiful moth known as the sphinx moth (Manduca quinquemaculata). Almost immediately after hatching, the tiny larvae begin eating their host plant in order to continue their development. 

When they reach the end of their life cycle, they detach from the plant, crawl into the ground, and transform into their adult form, the sphinx moth. When the pupation stage is over, stunning sphinx moths reemerge and search for ripe tomato plants on which to lay their eggs, and the cycle starts again.

Keep reading to learn more about these nasty garden pests and how to get rid of them.    

What Are Hornworms? How To Identify Them

Tomato hornworms are the caterpillars of sphinx moths, which are also known as hummingbird moths. If you let them go unchecked, they will cause serious damage to your tomatoes

What Are Hornworms? How To Identify Them

If you’ve ever grown tomatoes, you’ve probably encountered these green caterpillar pests.

Tomato hornworms can be found in both the United States and Canada. They are able to blend in pretty well with the green foliage, and their constant feeding leaves the fruit and leaves with spots and evidence of being bitten. 

And contrary to what their name might imply, these ravenous feeders also gorge on eggplant, potatoes, tobacco, peppers, and other vegetables.

Related: How To Get Rid Of Tomato Worms For Good? The Ultimate Guide

Can You Identify A Tomato Hornworm When You See One?

Hornworms can take on two distinct roles or physical manifestations. The caterpillar stage of the tomato hornworm is more common and is well-known among gardeners. 

On the other hand, Tomato worms can change their outward appearance and take on an entirely new form as they age; specifically, they morph into enormous moths. 

It is essential to recognize these moths because they lay eggs that eventually hatch and give birth to hornworms. However, do not worry!

If you keep the following identifying points in mind, you will be able to recognize tomato hornworms in either of their two forms.

Tomato Hornworm As A Caterpillar 

Tomato hornworms, while in the stage of the caterpillar, can appear in various colors. Take, for example, the colors yellow, white, green, and red. 

Also, these caterpillars have been known to reach lengths of up to 12.7 centimeters (five inches), which can be startling at first glance. 

Furthermore, tomato hornworms are easily identifiable by their lack of markings and their light colors, such as yellow or white, during the early stages of their life cycle. 

On the other hand, a completely mature tomato hornworm will typically be green or red in color, with eight V-shaped patterns on each side of its body.

Tomato Hornworm In Moth Form

When the tomato hornworm has completed its life cycle, it transforms into a giant moth that is brownish-gray in color and speckled all over. They have a pattern of yellow spots along the sides of their abdomen, and their front wings are somewhat narrow. 

On the other hand, the back wings are considerably larger, measuring between 4 and 5 inches across. You can also see distinct streaks of contrasting dark and light colors on their back.

Life Cycle Of Tomato Hornworms

When a tomato hornworm caterpillar reaches its adult stage, it stops feeding on plants and begins digging a hole in the soil so that it can transform into a pupa. Once they dig a hole, they enter pupation, and the adult moths of the tomato hornworm will then emerge from their pupal stage in the soil of your garden in the following spring.

where do tomato hornworms come from

A tomato hornworm caterpillar can go from an egg to a fully developed adult in only three to four weeks.

After mating, the female moths deposit their eggs, which are round, smooth, and light green, on the underside and upper side of the leaf surfaces. When these eggs hatch, the young tomato hornworms will take around three to four weeks to mature into their full size. The final step is for them to drop back into the ground and pupate there.

After around two weeks have passed during the same season, the second generation of moths will emerge from the pupae. That is why you will observe two generations of tomato hornworms every year, and if you do nothing to stop them, they will destroy your tomato crops.

Related: What Is Eating Holes in Your Tomatoes? | Causes and Solutions

How To Identify Tomato Hornworm Damage

Caterpillars like these are hard to spot before serious damage has been done because of how well they blend in with their surroundings. However, if you are lucky, tomato hornworms can frequently be found eating on the upper leaves of the plants. 

Identify the damage

Midsummer is when hornworm damage begins and lasts throughout the growing season.

Tomato hornworms that are more mature will feed on tomato fruits in addition to the leaves of the tomato plant. Therefore, if you find that your tomato plant has scars on the surface of the fruit, blooms that have been munched on, or leaves that have considerable damage, it is quite likely that your tomato plant is infested with tomato hornworms. 

Tomato hornworms can also be identified by the presence of black and green dots on the leaves of the plant. As tomato hornworms feed, they release either black or dark green droppings. These droppings are quite easy to spot, and as a result, they serve as an excellent indicator of a hornworm infestation.

How To Get Rid Of Tomato Hornworms?

Using only natural and organic remedies, tomato hornworms can be exterminated in a short amount of time. The following are some options for you to consider.

How To Get Rid Of Tomato Hornworms?

If you have the time, patience, or a small garden, handpicking is an excellent control method for hornworms.

Handpicking & Drowning

Tomato hornworms can be controlled in several ways, one of the most basic and effective of which is to handpick them and drown them in soapy water in a bucket. 

These bugs do not exhibit any sign of biting behavior. So, simply picking them up with your bare hands and placing them in a pail of soapy water should be enough to end them.

Insecticidal Soap Spray

Another quick and inexpensive solution! However, for this to work, the tomato hornworms must come into direct contact with the spray. Therefore, you must spray the homemade insecticidal soap solution directly on the tomato hornworms.

Natural Predators

You can also naturally eliminate tomato hornworms by introducing some natural predators. Lady beetles, green lacewings, and ladybugs are all examples of common predator insects. These insects prey on the egg stages of caterpillars as well as young caterpillars.

Using Biological Insecticide

Biological insecticides are yet another option for eliminating tomato hornworms from your garden. A potent example of an organic and biological pesticide is the bacterium known as bacillus thuringiensis (Bt), which is poisonous to numerous species of caterpillars but is harmless to humans. Effectiveness relies on the caterpillars eating the bacterium. 

Therefore, you need to ensure that you cover every portion of the plant. 

Also, if you amend your soil with bacillus thuringiensis, you will be able to eliminate adult tomato hornworms and hatchlings and juvenile hornworms.

Related: Vegetable Tomato Leaf Curl Virus: What Are the Causes & How to Fix Them?

Conclusion

If you’re wondering what’s causing the holes in your gorgeous tomato plants, hornworms are most likely to blame. These pests are notorious plant eaters, and you may be providing a safe haven for them in your garden. However, to keep your prize plants safe, you’ll need to know how to spot these pests and what kind of garden pest management to employ.

Frequently Asked Questions (FAQs)

Are tomato hornworms poisonous?

Tomato hornworms are not poisonous and don’t bite or sting, so you can safely handle a tomato hornworm. However, because they consume toxins from the tomato plant, a nightshade family member, they may acquire enough toxins over time to be somewhat poisonous if ingested. However, some say they don’t store toxins from plants they eat.

Does a tomato hornworm turn into a butterfly?

Once they’ve completed their metamorphosis into moths, Tomato hornworms can be rather stunning in appearance. The adult stage of the tomato hornworm is a moth with a strong body and a common hawk moth or sphinx moth. In point of fact, these caterpillars are among the largest that can be found in the state of Colorado.

What do tomato hornworms eat?

Tomato hornworms and tobacco hornworms consume solanaceous plants, which are members of the nightshade family and include eggplant, tomatoes, pepper, and potato. However, tomatoes are usually their preferred food source. Furthermore, these insects can also consume solanaceous weeds like horse nettle, jimsonweed, and nightshade as food sources.

What happens if you touch a tomato hornworm?

Despite their scary appearance and the fact that they writhe frantically when handled, tomato hornworms are not dangerous to touch. Their large horn is also just an effort at hiding in plain sight. Furthermore, tomato hornworms do not bite or sting, and they are not poisonous to humans. In fact, handpicking is the best way to get rid of these nasty green monsters.

Should I get rid of tomato hornworms?

Hornworms’ camouflaging green coloring makes them difficult to spot at first glance amongst plant leaves. Even when the damage is extensive, these offenders remain undetected by hiding in plants. They spend the day concealed in the foliage and come out to feed at sunset, making the evening the best time to see them.

How many hornworms are usually on a tomato plant?

In most cases, you’ll only find a single hornworm on a tomato plant. Tomato hornworms get their name because these caterpillars, which feed exclusively on tomatoes, have a tail that looks like a horn. As a result, there is intense competition among individuals. So, if given the opportunity, tomato hornworms can fully defoliate a tomato plant by chewing its leaves.

What plants repel tomato hornworms?

You may prevent hornworms from eating tomatoes next year by growing dill or basil among your tomato plants. The basil plant leaves have an intense aroma that drives tomato hornworms and other types of flies away from tomato plants. Borage is another similar companion plant that has been shown to lower the population of hornworms effectively.

Sources For Further Reading

Tomato hornworms in home gardens. The University of Minnesota Extension. (2022). Retrieved 22 October 2022, from https://extension.umn.edu/yard-and-garden-insects/tomato-hornworms

Hornworm caterpillars on tomatoes. The University of Illinois. (2020). Retrieved 22 October 2022, from https://extension.illinois.edu/blogs/good-growing/2020-08-07-hornworm-caterpillars-tomatoes

Tobacco or Tomato Hornworm on Vegetables | University of Maryland Extension. (2022). Retrieved 22 October 2022, from https://extension.umd.edu/resource/tobacco-or-tomato-hornworm-vegetables

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