All About Tomato Hornworms
The majority of gardeners will agree that the most detrimental of all tomato pests is the dreaded tomato hornworm. Walking out to the garden that looked beautiful yesterday to find destroyed plants with missing leaves and chewed up tomatoes is heartbreaking.
Today we are going to chat all about the hornworm and what you can do to keep them out of your vegetable garden.
What are Tomato Hornworms
Tomato hornworms are bright green caterpillars with “horns” sticking out from the last segment of their abdomens. They like to hang out on your tomato plants and undo all of the hard work that you have poured into them.
They will stick mainly to the undersides of leaves where they will nibble away until their bellies are full… Then their babies will take over.
Don’t be surprised if you find these pests on other host plants from the nightshade family (like peppers and eggplants) as well.
Hornworm Life Cycle
Adult moths (sphinx moths & hawk moths) lay tiny green eggs on the leaves of tomato and other nightshade plants in the late spring (mid-May).
These eggs turn into hornworm larvae and are ready to feed by the beginning of June.
The larvae feed for about three weeks and then they begin preparing for metamorphosis.
When hornworm larvae are ready to transform, they burrow underground and then emerge as adult moths. The moths then lay their eggs on plant leaves and the cycle starts all over again.
Tobacco Hornworm vs. Tomato Hornworm
There are two main types of hornworms- tobacco hornworms & tomato hornworms.
The worms that we usually deal with in the south are technically tobacco hornworms. They are almost always referred to as tomato hornworms, however, because they are always tearing up tomato plants.
- A Tobacco hornworm has black stripes next to its diagonal white stripes and it has a red horn. The adult is called a sphinx moth. The sphinx moth has 6 orange spots on both sides of the abdomen.
- A Tomato hornworm has green stripes next to its white stripes and it has a blue horn. The adult is called a hawk moth. The hawk moth has 5 orange spots on both sides of its abdomen.
Almost everything else about these two insects is the same.
Since there are only tiny differences in the two types of hornworms (and they are killed in the same ways), I am just going to say “tomato hornworm” for the rest of this article. The information in this article can be applied to both the tomato hornworm AND the tobacco hornworm.
How to Identify Tomato Hornworm Damage
When tomato hornworms have been nibbling on your plants, you will notice entire leaves missing, half-eaten tomatoes, and black droppings on the leaves.
These tomato pests don’t typically eat tiny holes in the leaves… They devour every inch that they can.
How to Get Rid of Tomato Hornworms
Tomato hornworms will destroy a large amount of foliage in a small amount of time. Once you spot them in your garden, you have got to get rid of them ASAP.
They won’t give up unless you kill them or manually remove them from your plants or kill them where they are. So what are the best ways to get rid of tomato hornworms?
How to Remove Tomato Hornworms
You can remove the tomato hornworms that you see by hand picking them off of your plants. This is the most effective way to rid your garden of these damaging pests.
They camouflage almost perfectly with the leaves and stems of tomato plants so you may have to look closely to find them all.
Put them into a container and take them away from the garden area. Then, you can feed them to your chickens, put them in a bucket of soapy water, or smash them to keep them from crawling back to your tomatoes.
Another option is to create a sacrifice area if you prefer to not kill the hornworms.
You can have a tomato patch far away from your garden where you release the tomato hornworms. They can feed on this patch instead of your garden.
The issue with this is that they will turn into adult moths which will lay eggs and create more issues for you in the next gardening season.
How to Kill Tomato Hornworms
If you don’t want to pick the hornworms off by hand, you can use certain pesticides to kill them.
Insecticidal Soap is an effective option to get rid of tomato hornworms. It needs to be sprayed directly on small caterpillars.
You can also use Neem Oil sprayed directly on the hornworms or as a soil drench. Neem Oil contains Azadirachtin which mimics the hormones in the tomato hornworms and will cause them to stop feeding on your plants.
I don’t recommend commercial broad-spectrum pesticides because they can kill the beneficial insects in your garden in addition to the hornworms.
Introduce Natural Predators
You can use beneficial insects that are natural predators of the tomato hornworm to help reduce the load on your tomato plants.
Natural predators of the tomato hornworm include beneficial insects like parasitic wasps, lady beetles, and green lacewings.
- Parasitic wasps (paper wasps) kill the adult hornworms by laying wasp eggs just under the skin of the caterpillar. The eggs hatch and the wasp larvae feed on the hornworm until it dies.
- Lady beetles and green lacewings will kill the eggs and the larvae of the tomato hornworm.
- Chickens are also natural enemies of the tomato hornworm. Release a few chickens into your garden and they should make quick work of hornworms that are on your plants or burrowed into the ground.
How to Prevent a Hornworm Infestation
Remove Hornworm Eggs Before They Hatch
To prevent a tomato hornworm infestation, you can watch for hornworm eggs and remove them before they hatch.
You might want to let the chickens into the garden before planting to remove hornworm eggs and any hornworm larvae or pupae that may be in the soil. This will get rid of tomato hornworms before they have a chance to get started!
You can also till up your vegetable garden soil at the end of the season and in the spring to kill any hornworms that may have been riding out the winter underground.