Natural Ways to Get Rid of Tomato Hornworms

Understanding Tomato Hornworms

Tomato hornworms (Manduca quinquemaculata) are the larvae of a large moth. They feed on tomatoes and other nightshade plants (like peppers and eggplants), chewing through leaves, stems, and sometimes fruit. They can grow up to four inches long and are well-camouflaged, making them hard to spot until significant damage has occurred57.

Signs of hornworm infestation include:

• Missing leaves or stems stripped bare overnight

• Large green caterpillars on plants

• Small black droppings (frass) on leaves or ground

• Chewed or scarred fruit

1. Handpicking: The Most Reliable Natural Method

Handpicking is the most effective and immediate way to control hornworms, especially in small gardens356710. Here’s how to do it:

• Inspect plants daily, especially in the morning or evening when hornworms are most active.

• Look for chewed leaves and droppings as clues to their location.

• Shine a flashlight or use a blacklight at night—hornworms glow under UV light, making them easy to spot18.

• Wear gloves if squeamish, and remove hornworms by hand.

• Drop hornworms into a bucket of soapy water to kill them, or feed them to chickens or birds1610.

Repeat this process every day or two during peak season, as new eggs may hatch even after you’ve cleared existing worms17.

2. Organic Sprays and Natural Remedies

Bacillus thuringiensis (Bt)

Bt is a naturally occurring soil bacterium that targets caterpillars but is harmless to humans, pets, and most beneficial insects457. It works best on young hornworms (less than two inches long):

• Mix Bt powder with water according to package instructions.

• Spray directly onto tomato foliage, focusing on the undersides of leaves.

• Reapply after rain or as needed.

Bt acts as a stomach poison for caterpillars, killing them after ingestion.

Neem Oil

Neem oil is a natural pesticide that disrupts hornworm feeding and growth57. To use:

• Mix one tablespoon of neem oil with two cups of water and a few drops of dish soap.

• Spray infested plants, especially leaf undersides.

• Repeat every 7–10 days or after rain.

Neem oil can also deter other pests, but use with care as it may affect beneficial insects57.

Homemade Garlic or Pepper Sprays

• Garlic spray: Crush several garlic cloves, steep in water, strain, add a teaspoon of liquid soap, and spray on plants. The strong smell repels hornworms578.

• Cayenne or hot pepper spray: Mix one teaspoon of cayenne pepper, one teaspoon of garlic, and one teaspoon of dish soap in a gallon of water. Blend, strain, and spray on plants68.

• Baking flour: Dusting plants with flour can cause hornworms to bloat and die after eating treated leaves2.

Always test sprays on a small area first to ensure your plants aren’t sensitive.

Diatomaceous Earth (DE)

DE is a powder made from fossilized algae that damages the exoskeleton of insects, causing them to dehydrate and die57. To use:

• Dust food-grade DE on and around tomato plants, especially after rain.

• Reapply as needed.

• Wear a mask to avoid inhaling the fine powder.

3. Companion Planting and Barriers

Companion Planting

Certain plants repel hornworms or attract beneficial insects that prey on them. Try interplanting the following with your tomatoes:

• Basil

• Marigolds

• Borage

• Nasturtiums

• Mint

• Dill, yarrow, oregano, parsley, mustard1679

These plants can mask the scent of tomatoes or attract predators that feed on hornworms.

Physical Barriers

• Floating row covers can keep adult moths from laying eggs on your plants. Remove covers when plants flower to allow pollination7.

• Mulch with wood chips or pencil shavings around the base of plants to deter caterpillars from crawling up5.

4. Encourage Natural Predators

Hornworms have many natural enemies, including:

• Braconid wasps: These tiny wasps lay eggs on hornworms, which hatch and consume the caterpillar from the inside out. If you see a hornworm with white rice-like cocoons on its back, leave it—these wasps will help control the population7.

• Birds, ladybugs, lacewings, spiders, and praying mantises: Attract these beneficial insects by planting a diverse garden and avoiding broad-spectrum pesticides711.

5. Cultural and Preventive Practices

Crop Rotation and Soil Management

• Rotate crops: Avoid planting tomatoes or other nightshades in the same spot year after year to reduce pest buildup7.

• Till soil in fall: Tilling after harvest can destroy up to 90% of overwintering hornworm pupae, reducing next year’s population37.

Remove Plant Debris

• Clear out old plants and weeds: This removes hiding spots and food for hornworm moths and larvae7.

Grow Healthy Plants

• Well-fed, healthy tomato plants are more resilient to hornworm damage. Use compost, water regularly, and ensure good drainage3.

6. Monitoring and Frequency of Application

• Check plants at least twice a week during the growing season57.

• Apply sprays or dusts after rain or as needed to maintain effectiveness257.

• Handpick daily during peak infestation for best results167.

7. What to Do With Hornworms After Removal

• Dispose in soapy water to kill them quickly1610.

• Feed to chickens or wild birds if you have them—hornworms are a nutritious treat16.

• Do not compost live hornworms, as they may survive and pupate.

8. Signs of Overuse or Problems

• Neem oil and soaps can harm beneficial insects if overapplied—use targeted sprays and avoid spraying flowers57.

• Diatomaceous earth is non-selective and can affect pollinators—apply carefully and avoid flowers.

• Monitor for plant sensitivity with any homemade spray.

9. Frequently Asked Questions

How often should I handpick hornworms?
Check daily during peak season, or at least every other day. Early intervention prevents major damage167.

Are hornworms dangerous to humans?
No, they do not bite or sting and are safe to handle with gloves6.

Is it okay to leave hornworms with white cocoons on them?
Yes, these are parasitized by beneficial wasps and should be left to support natural pest control7.

Can I use commercial organic pesticides?
Yes, products containing Bt, spinosad, or pyrethrin are effective and approved for organic gardening, but natural methods are usually sufficient57.

Conclusion

Tomato hornworms can devastate your garden, but with vigilance and a combination of natural methods, you can keep them in check without resorting to harsh chemicals. Handpicking, organic sprays (like Bt, neem oil, and garlic or pepper solutions), companion planting, encouraging beneficial insects, and good garden hygiene are all effective, sustainable strategies. By integrating these practices and monitoring your plants regularly, you’ll protect your tomatoes and keep your garden ecosystem healthy and balanced.

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