If the big green tomato hornworm caterpillars are preventing your tomatoes and peppers from staying on vine, you are probably asking “where do tomato hornworms come from?”
Tomato hornworms are a common garden pest found in the larval stage of the five spotted hawk moth, manduca quinquemaculata.
Tomato hornworms come from eggs laid individually by the female five spotted hawk moth on host plants towards the end of spring, just in time for you to provide them with some home-grown gardening labor and effort.
If the tomato hornworm pest has run you ragged and you are looking for strategies to delay or get rid of them from your garden, then this article is going to cover everything you need to know about the tomato hornworm and how to control and get rid of them in your garden!
Just What Exactly Are These Tomato Hornworms?
The tomato hornworm, the larval stage of the five-spotted hawk moth, is prevalent in both North America and Australia.
Tomato hornworms,also closely related to the tobacco hornworm that is the most common in states of the southern United States.
Here is information about the tomato hornworm:
- They emerge from solitary eggs laid by adult moths on the plants that will become a home and food for newly hatched and very hungry caterpillars.
- The eggs are laid on the underside of the leaves of a host plant to incubate for 7 days.
- The m. quinquemaculata larvae develop into large, bright green caterpillars with a large, dark-colored “horn” on their behind that give them their name. They can grow to more than 10cm (3.9 inches) in length.
- They have generally 7 to 8 white V-shaped patterns on their body with blue-black spiny projections along their sides.
- The tomato hornworm would stay in a larval form for up to six weeks while they eat voraciously, then burrow into the ground and form a cocoon.
Moreover, they can live through the winter months in the state of a pupa. They can also mature into adult moths as quickly as three weeks once they have buried themselves.
The moths come out of their chrysalis in the spring and are ready to mate and lay their eggs again. Considering how colourful the pupae are in form of that bright green color, the obviously brown-grey moths appear somewhat drab.
If You Don’t Recognise the Tomato Hornworm, You’ll Definitely Recognise Its Handiwork
Gardeners who are passionate about growing a respectable crop will relate to the feeling of despair when they discover chewed leaves and fruits.
Because the tomato hornworm is green, it might not be easy to find.
Indicators of tomato hornworm feeding activity include:
- Chewed leaves
- Missing leaves
- Wilted leaves
- Large holes in leaves
- Extensive defoliation
- The tops of plants eaten away
- Whole flowers eaten
- Scarred fruits
- Dark green/black droppings
- Sun damaged fruits due to loss of leaf cover
- White cocoons of the 5 spotted hawk moth
Tomatoes Aren’t the Only Target of the Tomato Hornworm
The tomato hornworm derives its name from its primary host, the tomato plant.
The five-spotted hawk moth (or tomato hornworm moth) can be found laying eggs on the underside of tomato leaves.
They can also be found targeting other nightshades, of which tomatoes belong, in the Solenaceae family.
These plants include:
- Bell peppers
- Tomatillos
- Hot peppers
- Eggplants
- Potatoes
- Watermelons
- Blueberries
- Physalis
- Goji berries
Do Tomato Hornworms Bite or Sting?
While many kinds of caterpillars possess a defensive tool of some sort, the tomato hornworm caterpillars are safe to handle.
In other words, its horns are not sharp, and the caterpillar cannot bite or sting you. So, it’s perfectly fine to grab them directly off of the plant that you found them on!
Control and Prevention of Tomato Hornworms
Because the tomato hornworm is such a relentless feeder, if you have any hope of salvaging your vegetable garden harvest, it’s a good idea to deal with these pests as soon as you see them.
Here are a few ways to get rid of these annoying caterpillars:
- Remove the caterpillars from the plants and throw them into a bucket of soapy water. Tomato hornworm caterpillars can also be composted, as they will quickly die after being removed from their host tomato plant.
- If you have backyard chickens or ducks, you can give them access to these caterpillars as a good snack. Whenever I introduce a tomato hornworm caterpillar to my chickens they want to have a little battle over who gets to eat it. So, if you have chickens at home and don’t want them out digging up your plants, either hand-pick the caterpillar off and give it to your poultry or supervise them while they enjoy one as a special treat until they are done.
- Encourage natural predators of the tomato hornworm caterpillar. Natural predators of the tomato hornworm caterpillar can be just as abundant as the tomato hornworm caterpillar, which will help to keep the population down, so you don’t have to. The most common predators of the tomato hornworm caterpillar include ladybugs, lacewings, entomophagous wasps (generalists), and parasitic wasps.
- Use insecticidal soaps to kill the hornworms. You can even mix the soap with garlic and cayenne pepper for a more effective deterrent that will stop the caterpillar from stripping the leaves off of your tomato plants.
- Using pesticides should never be the first option for managing tomato hornworm caterpillars. But when you discover that it is essential to use pesticide, always take the more targeted approach. You’ll have to make sure that you spray the leaves the tomato hornworm caterpillar is going to consume to have the poison consumed by the caterpillar. Bacillus thuringiensis (Bt), is one of the most effective organic biological pesticides. Bt is a bacteria toxic to many caterpillars that simply needs to be sprayed on the plants, and reapplying after the rain.
Great Strategies for Keeping Your Tomatoes to Yourself
You will be battling the tomato hornworm caterpillar every year if you do not have a long term prevention in place.
However, by modifying your gardening habits you can keep these persistent green pests away.
Here are three things you can try:
- Enhancing Biodiversity: As you create a welcoming habitat for all kinds of insects and wildlife, birds and wasps, which are natural predators, will consume tomato hornworm larvae before they can cause serious damage. Planting wildflowers or creating bug hotels are two simple ways to increase the biological controls you already had.
- Utilizing Tillage: Tilling will disturb and destroy overwintering pupae that will become next years’ generation of the moth. You will be literally destroying the tomato hornworm where it comes from. By deep tillage before and after your gardening season, we are taking away their habitat and hiding places.
- Companion Planting: Companion planting is a method that has been utilized by horticulturists to deter pests for thousands of years. Basil, tagetes, marigolds, and dill are common pest deterrents.
Tomato Hornworms Don’t Need to Herald the Demise of Your Vegetable Patch
You can happily equip yourself with a myriad of methods of slaying tomato hornworm caterpillars on your plants.
As with the many aspects of gardening, the ideal solution is diligent effort and applying sprays and bi-annual tilling to give your tomato crop the pain relief they desperately need.