Tomato hornworms are found throughout the US and are notorious in ruining tomato crops. They have a green color and can easily blend in your garden greenery and feed on your precious leaves and stems.
In this post, we will tackle how to get rid of tomato hornworms and learn the fundamental stuff behind such caterpillars.
Eliminating tomato hornworms include utilizing insecticides, pesticides, spray, as well as releasing beneficial insects, roto-tilling, and a secret trick which you’ll come to know as you read the post.
- 1 What Is Tomato Hornworm?
- 2 Tomato Hornworm vs Tobacco Hornworm
- 3 How to Know If Your Tomato Plant Is Infected
- 4 How to Prevent Tomato Hornworms
- 5 How to Get Rid of Tomato Hornworms
- 6 Summary
What Is Tomato Hornworm?
Scientifically referred as Manduca quinquemaculata, tomato hornworms are common garden pests feeding on the nightshade (Solanaceae) plant family which includes tomatoes. Other plants in the same family include potato, eggplant, and peppers.
Sphinx moth or hawk moth refer to the adult form of tomato hornworms which have large sizes and robust attributes. They are active from dusk till dawn.
Read more: Different Types of Tomatoes
Tomato Hornworm vs Tobacco Hornworm
Now these two are commonly confused from each other. You can’t blame those who do since the two are similarly-looking. Further, tobacco hornworms also feed on the same plant family.
Tomato Hornworm indicators
- White and black markings and dominantly pale green in color
- Up to 5 inches long
- Has V-shaped stripes throughout the green body
- Horn-like protrusion stemming from the rear part
Tobacco Hornworm indicators
- A red horn on their tail end; hornworms have black horns instead
- Parallel white stripes; hornworms have V-shaped marking instead
- Black spots lining every stripe; tomato hornworms don’t have this
How to Know If Your Tomato Plant Is Infected
There’s no other way to determine whether your plant is infected but by physical inspection. The hornworm’s green color almost blends with the leaves of your plant so look closely as they can almost camouflage with the greenery.
Daily inspection can help a lot in detecting small caterpillars and hornworm eggs.
- Notice the missing leaves and stems; white cocoons might be nearby
- Specifically inspect the top of your tomato leaves and look for dark green toppings
- Also inspect the underside of the leaves; it’s where the hornworms most-likely will be
Read more: Blight on Tomatoes
How to Prevent Tomato Hornworms
While you may not be able to prevent hornworms from disturbing your peaceful plants this season, you can at least make sure they won’t come back next year. Interplanting is recommended to keep pests away. Plants that make an excellent companion to tomatoes include marigolds, basil, and dill.
Read more: Best Fertilizer for tomatoes
Not all insects are your enemies. Wasps for instance serve as biological control by feeding on hornworms which makes them highly beneficial insects.
If you see wasps around your tomato plants, worry not and let them be. They are most likely there to attack and speed up the life cycle of existing hornworms.
You can confirm such act of nature if you see hornworms attached with parasitic wasp larvae; which appears like tiny white grains of rice. While the hornworms can still feed on your plant, it won’t be long before they ultimately die from wasp attacks.
Know that you don’t always have to wait for the hornworms to die. Once you see infected hornworms, you can manually remove and transfer them to a spot far from your plants. That way, the wasp can still do their thing while preventing the hornworms from destroying your crop at the same time.
Destroy overwintering larvae
It has been studied that tilling has a staggering 90 percent success of causing mortality to overwintering larvae. You can do so by tilling the soil at the start and end of every gardening season.
How to Get Rid of Tomato Hornworms
You can implement this solution if there are way too many hornworms infesting your garden. Insecticides are known to be an effective control medium. If you’re concerned about downsides, you can always opt for organic pesticides.
Before buying anything, always do some research first or consult a local professional to have a list of approved pesticides to use.
It’d be great if your insecticide is organic and formulated as a bacterium that serves as a stomach poison on unwanted insects. That way, you will be eliminating the bad ones while not harming other plants and animals.
For better results, you should also apply the organic insecticide deep on the plant canopy (the place where insects usually hide). Importantly, you should also apply it to the leaves’ undersides.
The most harmless – and most common way – of getting rid of tomato hornworms is to simply handpick and get rid of them for good. However, this is only ideal if you have patience and the time; or if you only have a small garden to take care.
One important thing to know is that these caterpillars are not harmful. They certainly do not sting and not dangerous when you touch them. For your peace of mind, always wear gloves and other necessary garden gear when dealing with the said hornworms.
Now what can you do after picking them? You can either feed them to your chickens if you have or simply throw them on a bucket of soapy water to be disposed of later.
Here come the wasps again. Not only do they help you eliminate hornworms for the next season, but they can also be your solution today. Examples of wasps that can help are Trichogramma, braconoid, and lacewings. Further, ladybugs also attack the hornworm eggs so it’d be nice to keep them around.
Pesticide + Insects
You don’t have to get stuck choosing between keeping friendly insects or using pesticides as you can harness the power of both. The trick here is to use a natural, short-lived, and less toxic pesticide to gain control of the high hornworm count.
Once population control is established, you can then utilize the power of predatory insects by releasing them into your garden. That way, you can maintain control.
Use Diatomaceous Earth
Here’s the secret trick mentioned in the intro above. You are probably familiar with Diatomaceous Earth on swimming pool filter applications. Also known as D.E., this is a naturally occurring sedimentary rock that is soft enough to be easily crushed into a fine white powder.
The beauty of Diatomaceous Earth lies on its multiple benefits to your tomato plant and how it offers long-lasting protection. D.E. can effortlessly kill an insect by piercing through and damaging its outer layer.
Diatomaceous Earth basically looks like broken glass under the microscope. Imagine an insect crawling through the said little pieces of sharp glasses. You can expect the insect to die eventually due to damaged outer layer. The best part? D.E. contains zero toxic poison!
An insect spray is quite promising especially if you’re dealing with young caterpillars. There are also available garden dust you can utilize for the same purpose.
This method is effective after harvest as it can terminate overwintering soil pupae. They are commonly large and aren’t buried deeply so destroying them by roto-tilling is pretty easy.
Adult moths typically lay eggs on the foliage undersides. It will only take a week before the said eggs hatch. When uncontrolled, the larvae will feed on your precious plants for up to 6 weeks. After which, they transform into cocoons, over-winterize, and emerge as moths.
That said, it’s a great idea to learn how to get rid of tomato hornworms. Not only can you do reactive solutions, but you can also implement proactive methods so you never have to deal with caterpillars anymore.
Read more: How to Treat Tomato Timber Rot