If you’ve found large, green caterpillars stripping your tomato plants bare, you’re likely asking, what eats hornworms? These hungry pests can decimate a garden quickly, but nature provides a whole team of predators and parasites ready to help. You don’t have to fight them alone. This guide will show you how to identify these natural allies and create a garden that invites them in.
What Eats Hornworms
Hornworms are a favorite food for many beneficial creatures. By understanding who they are, you can spot them at work and learn to protect them. Their presence is a sign of a healthy, balanced ecosystem right in your backyard.
Birds: The Daylight Patrol
Many common backyard birds consider hornworms a tasty snack. They are excellent at spotting these large caterpillars from above.
- Robins and Bluebirds: These ground-foraging birds will pick hornworms off your plants and the soil beneath.
- Chickadees and Sparrows: Smaller birds will peck away at younger, smaller hornworms.
- Wasps (Not the stinging kind): Specifically, songbirds like cardinals and grosbeaks are adept hunters.
To attract these birds, provide a fresh water source like a birdbath. Dense shrubs and native plants offer them shelter and nesting sites, encouraging them to stick around and hunt.
Parasitic Wasps: The Hidden Heroes
This is one of the most effective natural controls. These tiny, non-stinging wasps don’t eat the hornworm themselves. Instead, they use it as a living nursery for their young.
The most common is the Braconid wasp. The female lays her eggs under the hornworm’s skin. When the eggs hatch, the larvae feed on the caterpillar from the inside. You’ll know they’re at work when you see a hornworm covered in small, white, rice-like cocoons. The caterpillar is still alive at this point but will soon stop feeding and die.
Important: If you see a hornworm with these cocoons, leave it in your garden. Do not remove it. Those cocoons will produce a new generation of parasitic wasps that will protect your plants for weeks to come.
Other Insect Predators
A variety of insects will prey on hornworm eggs and the smaller caterpillars. These soldiers work on the front lines.
- Lady Beetles & Lacewings: Their larvae are voracious predators of hornworm eggs and tiny caterpillars.
- Green Lacewings: Often called “aphid lions,” their larvae will also consume young hornworms.
- Praying Mantises: These generalist hunters will take down hornworms of almost any size if they can catch them.
Planting a variety of flowers, especially ones with small blooms like dill, yarrow, and cosmos, provides nectar for the adult forms of these beneficial insects.
Ground Predators
When hornworms get full and drop to the ground to pupate, a new set of predators awaits them.
- Spiders: Ground and wolf spiders will readily capture them.
- Fireflies: The larvae of fireflies are predatory and hunt in soil litter.
- Ground Beetles: These fast, nocturnal hunters patrol the soil surface for soft-bodied prey.
Maintaining a light layer of mulch or leaf litter gives these predators a habitat to live and hunt in. Avoid disturbing the soil too much where they might reside.
How to Encourage Natural Predators in Your Garden
You can’t just hope these helpers show up. You need to roll out the welcome mat. Creating a diverse garden ecosystem is the key to long-term pest control.
1. Stop Using Broad-Spectrum Pesticides
This is the most important step. Chemical sprays and dusts don’t discriminate. They will kill the beneficial insects and spiders just as fast as the pests. If you must intervene, use targeted options like Bt (Bacillus thuringiensis), a natural bacteria that only affects caterpillars when they eat it.
2. Plant a Diversity of Flowers
Beneficial insects need nectar and pollen, especially as adults. By planting a continuous bloom of different flowers, you provide them with the food they need to reproduce and stay in your garden.
- Early Season: Alyssum, dill, cilantro (let it flower).
- Mid Season: Cosmos, zinnias, marigolds, sunflowers.
- Late Season: Goldenrod, asters, sedum.
3. Provide Water and Shelter
A simple shallow dish with stones and water helps tiny insects drink. Leave some areas a little wild—a pile of rocks, a stack of old wood, or perennial plants left standing over winter offer crucial over-wintering sites for predator eggs and larvae.
4. Practice Tolerance
A few hornworms or aphids are not a crisis. They are the food that attracts and sustains your predator population. If you wipe out all the prey immediately, the beneficials have no reason to stay. Let a small problem exist to solve the bigger one naturally.
Manual Removal: When You Need to Step In
Sometimes, the predator population needs a little help, especially early in the season. Here’s a safe, effective way to manually control hornworms.
- Go out to your garden at dawn or dusk with a bucket of soapy water. The hornworms are most active and easier to spot during these cooler times.
- Check the stems and leaves of your tomatoes, peppers, and eggplants. Look for missing leaves and dark green droppings (frass) on leaves below.
- Pick off any hornworms you find and drop them into the soapy water. Remember to check for those white parasitic wasp cocoons first—if you see them, leave that caterpillar be.
Using a blacklight flashlight at night can make this even easier. Hornworms glow under UV light, making them shine brightly against the dark leaves so you can find them.
Common Questions About Hornworm Control
What animal eats tomato hornworms?
As listed above, birds like robins and cardinals are big predators. Wasps, ladybugs, and ground beetles also contribute. Even a few species of small mammals might eat them if they find them.
What are the white things on a hornworm’s back?
Those are the cocoons of the Braconid parasitic wasp. This means the hornworm is already being controlled and will not cause more damage. It’s best to leave it so the wasps can complete their life cycle.
How do I attract wasps that kill hornworms?
Plant lots of small-flowered herbs and plants. Dill, fennel, parsley, and Queen Anne’s lace are excellent choices. These provide the nectar the adult wasps need. Also, avoid spraying any pesticides that would harm them.
Will hornworms kill my tomato plant?
A severe infestation can defoliate a plant very quickly, stressing it and reducing your harvest. One or two large hornworms can strip a small plant in just a couple days. Regular monitoring is your best defence.
What is the difference between a tomato hornworm and a tobacco hornworm?
They look very similar and both eat solanaceous plants (tomatoes, peppers, etc.). The tomato hornworm has eight V-shaped markings and a black horn. The tobacco hornworm has seven diagonal white stripes and a red horn. Their natural predators attack both species equally.
Building a garden full of life is the best defense against pests like the hornworm. When you encourage birds, insects, and spiders, you create a resilient system that manages problems for you. It takes a little patience, but the reward is a vibrant, healthy garden that thrives with less work from you. Start by planting a few extra flowers this season and see who shows up to help.