Have you noticed large green caterpillars eating your tomato plants? Then there’s a good chance your plants are being eaten by tomato hornworms – or their close relative, the tobacco hornworm.
A common pest of tomatoes, these greedy caterpillars can quickly destroy the leaves of tomato plants as well as peppers, eggplants and potatoes. You’ll need to act quickly to get rid of hornworms, as they can invade a vegetable patch in record time.
Tomato hornworm is the larva of the five-spotted moth (Five-spotted Manduca), and is more common in northern states, while the tobacco hornworm is the larva of the Carolina Sphinx moth (Manduca Friday) and more common in the South.
Controlling these pests is key to growing perfect tomatoes by nurturing healthy, high-yielding plants.
What does a tomato hornworm look like?
Despite their large size — up to 4 inches long — tomato hornworms tend to blend into foliage, so you may see their infestation before you realize it.
Check your plants regularly for leaf drop, large holes, fallen flowers, and damaged fruit. You may also notice black worm droppings on the leaves.
Tomato and tobacco hornworms look similar but have some differences:
- Tomato hornworms are bright green caterpillars with white stripes that form a series of V-shapes. They have dark green horns with black edges.
- Tobacco hornworms have red horns and white diagonal stripes, rather than a V shape.
- You may also find other moth larvae visiting your plants, such as the darker-colored hummingbird moth larvae. However, tomatoes are not usually their preferred meal.
Usually, when one tobacco moth or tomato hornworm caterpillar is found, others will appear in the area as well.
(Image source: Alamy)
Should I kill tomato hornworms?
Hawkmoths and Sphynx moths are nocturnal pests and pollinators. However, they are common and pose no threat. So if tomato hornworms or leafminers are infesting your plants, the best way to save them is to kill them.
In the future, try controlling infestations by repelling moths and their larvae from your plants using the methods outlined below.
How to kill tomato hornworms naturally
Getting rid of tomato hornworms naturally is the best solution. Chemical pesticides can leach into plants and soil, killing beneficial insects and disrupting the biodiversity in your garden. However, early action is key, so keep a close eye on your plants.
Here, we will reveal the best solutions for immediate treatment as well as preventive measures to minimize the risk of hornworm recurrence.
1. Pick them up by hand
It may sound unpleasant, but picking tomato hornworms by hand is the best way to control an ongoing infestation. Hornworms do not bite, and their large size makes them easy to handle. Wear gloves if you have a weak heart!
Check your plants daily – the best time to do this is in the evening, when caterpillars are most active. Shine a flashlight on the plant to highlight the caterpillars and carefully examine each leaf and stem, looking at both the underside and the top.
When you find a hornworm, pull it off the plant and drop it directly into a bucket of soapy water. Also, if you have chickens, save the hornworms for food. They will love to eat them.
(Image source: Shutterstock)
2. Repel them with homemade spray
If you can’t handle—or can’t bear to—handle the hornworms, you can treat them with a homemade spray. This recipe uses cayenne pepper, which hornworms hate. It’s more of a deterrent than a cure, but it can kill them:
- Add 1 cup water, 1 tablespoon dish soap, and ¼ teaspoon cayenne pepper to the bottle. Shake well.
- Spray the leaves, including the underside. You will need to do this several times a week, especially after it rains.
- Instead of adding it to a spray bottle, you can lightly sprinkle cayenne pepper directly onto the affected area.
3. Use of bacterial pesticides
If you are having trouble managing tomato hornworms, try using Bacillus thuringiensis (Bt), a natural pesticide allowed for use in organic farming.
Bt is a naturally occurring bacterium found in some soils that infects certain insects – especially leaf- and needle-eating caterpillars. It contains a crystalline protein that paralyzes the caterpillar’s digestive system. Within a few days, the caterpillar stops eating and starves to death.
Bacillus thuringiensis It is harmless to humans and beneficial insects, although it will kill butterfly larvae, so use only on affected crops that are infested.
Usually used as a spray, it is most effective when the caterpillars are still small and have not had a chance to cause serious damage, so check your plants daily.
(Image source: Getty Images)
4. Attract predatory insects
Predatory insects are your best friends in the fight against tomato hornworms, doing the dirty work for you. However, they are not a quick fix and should be encouraged as part of a long-term control plan.
Braconid wasps lay eggs on tomato hornworms, and the larvae eat the caterpillars from the inside out. If you find tomato hornworms in your garden covered in white rice-like sacs, leave them alone as the wasps will mature and the hornworms will die. The adult wasps will then produce more wasps and kill more hornworms.
Ladybug And green lace Will also eat young caterpillars or eggs. Both can be purchased and added to the garden.
You can attract predatory insects to your yard by planting favorite plants like alyssum, Dill, mugwort, white cloverand marigolds.
5. Prevent hornworms with companion plants
Tomato Companion Plants extremely valuable in controlling tomato hornworm and other pests such as arrange And aphidTheir flowers or leaves emit a strong scent that repels harmful insects, but attracts many beneficial insects and pollinators.
Borage, basil, marigolds and watercress work particularly well – intercrop them with your tomato plants.
In addition to pest control, intercropping has other benefits, boosting nutrients and even improving flavor.
