How to Get Rid of Tomato Hornworms Naturally
The fastest way to control tomato hornworms is to hand-pick them off plants in the morning when they are sluggish. For larger infestations, spray with Bt (Bacillus thuringiensis), an organic caterpillar-specific bacteria. Encourage parasitic wasps by planting dill and parsley - if you see white cocoons on a hornworm, leave it alone as beneficial wasps will emerge.
- •Large sections of leaves eaten overnight
- •Dark green or black droppings (frass) on leaves and ground
- •Stripped stems with only veins remaining
- •Damaged or eaten green tomatoes
- •Large (up to 4 inch) green caterpillars with white stripes and horn
Sphinx Moth Lifecycle
Tomato hornworms are the larval stage of the five-spotted hawk moth. Adult moths emerge from soil-overwintering pupae in late spring, mate, and lay eggs on tomato family plants. Caterpillars feed voraciously for 4-6 weeks before pupating in soil.
Lack of Natural Predators
Gardens without diverse plantings often lack parasitic wasps and other beneficial insects that naturally control hornworm populations. Monoculture gardens are more susceptible to severe infestations.
Overwintering Pupae
Hornworms pupate in soil near host plants. If not disrupted by fall tilling, they emerge the following spring. Gardens with hornworm problems in previous years often see repeat infestations.
Solutions
- 1.Scout plants in early morning when hornworms are visible
- 2.Look for dark droppings first to locate feeding areas
- 3.Follow defoliated stems to find the well-camouflaged caterpillars
- 4.Drop hornworms into bucket of soapy water to kill them
- 5.Check plants daily during peak season (July-August)
- 1.Purchase Bt var. kurstaki (Btk) specifically for caterpillars
- 2.Mix according to package directions
- 3.Spray all leaf surfaces, including undersides
- 4.Apply in evening as Bt degrades in sunlight
- 5.Reapply after rain or every 5-7 days
- 1.Plant dill, parsley, and fennel to attract braconid wasps
- 2.If you see hornworm covered with white rice-like cocoons, DO NOT KILL IT
- 3.The cocoons contain beneficial wasp larvae that will emerge and parasitize more hornworms
- 4.Avoid broad-spectrum pesticides that kill beneficial insects
- 5.Allow some herbs to flower throughout the season
- 1.Plant basil near tomatoes - its scent may deter adult moths
- 2.Interplant with marigolds and borage
- 3.Grow trap crops like datura (jimsonweed) away from garden
- 4.Maintain diverse plantings to support beneficial insect populations
- 5.Avoid large monoculture tomato plantings
- Till soil in fall and early spring to expose overwintering pupae
- Use row covers on young plants until they flower
- Rotate tomato family plants to different locations each year
- Plant trap crops away from main garden to draw moths away
- Attract beneficial insects with diverse flowering plants
- Inspect transplants carefully before planting
- Use black light traps to catch adult moths at night
What is the difference between tomato and tobacco hornworms?
Both look similar and cause the same damage. Tomato hornworms have V-shaped white markings and a black horn, while tobacco hornworms have diagonal white stripes and a red horn. Control methods are identical for both species.
Should I kill hornworms with white cocoons on them?
No! Those white cocoons are pupae of braconid parasitic wasps. The wasp larvae have consumed the hornworm from inside and will emerge as adult wasps that will parasitize more hornworms. Leave parasitized hornworms to support natural pest control.
Will hornworms come back next year?
Yes, if pupae overwinter successfully in your soil, hornworms will return. To break the cycle, till soil after frost to expose pupae to predators and cold. Rotate where you plant tomatoes each year to reduce localized populations.
Are tomato hornworms dangerous to touch?
No, tomato hornworms are harmless to humans. The "horn" is soft and cannot sting or bite. They may thrash when handled but cannot hurt you. Feel free to hand-pick them without gloves.
Related Problems
Why Are My Tomato Leaves Turning Yellow
Yellow tomato leaves are most commonly caused by nitrogen deficiency, overwatering, or early blight ...
How to Fix Blossom End Rot on Tomatoes & Peppers
Blossom end rot is caused by inconsistent watering that prevents calcium from reaching developing fr...
How to Get Rid of Aphids on Vegetable Plants Naturally
The most effective natural aphid control is a strong spray of water to knock them off plants, follow...