How To Identify Tobacco Hornworm And Control / Prevent Them On Tomato Plants?

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Quick Answer: How To Identify Tobacco Hornworm And Control Them On Tomato Plants?

Tobacco hornworms are one of the common caterpillars that trouble tomato plants and defoliate them. Natural measures, including Bt spray and DE powder can help in controlling the tobacco hornworm population. The effective physical method is handpicking the hornworms and immersing them in soap water. Chemical sprays made of spinosad or insecticidal soap have also proven effective in controlling these caterpillars.

This comprehensive guide will help you identify and control one of the pests troubling tomato plants, tobacco hornworms.

Keep reading to know more!

What Is Tobacco Hornworm And How Does It Harms Tomato Plants?

The tobacco hornworm (Manduca sexta), also known as the tobacco hawk moth, is a common pest of the Solanaceae family. It has seven white diagonal or straight lines with a black border and red horns.

It primarily consumes the foliage of tomato plants. It can also damage fruits, blossoms, and stems.

Here is a video on tobacco hornworms:

How To Confirm That Tobacco Hornworm Is Troubling Your Tomato Plants?

Check for the tomato plants regularly for pests. It can be easily spotted due to its size. You may observe the chewed or missing leaves from the top of the plant.

You may also find wilted leaves or white cocoons nearby. The fruits may suffer sunscalding because of the reduced foliage cover. Another popular telltale sign is the green or black droppings left by the hornworms on the plants.

Click this video on signs of tobacco hornworm damage:

Natural Ways To Control Tobacco Hornworm On Tomato Plants

Tobacco hornworm can be controlled in many ways and requires immediate management if the pest is detected.

The effective natural methods are the use of BT spray and sprinkling DE powder. These methods are non-toxic and effective.

Method 1- Apply BT Spray

Bacillus thuringiensis (subspecies kurstaki) is a natural bacteria effective on young caterpillars less than 0.5 inches.

It will paralyze the digestive system of tobacco hornworms and cause them to stop feeding and die. It is available as powders to concentrated liquids.

  • Dilute Bt– The regular Bt can be diluted with water in a small spray bottle or garden sprayer. Follow the manufacturer’s instructions for the proper dilution ratio.
  • Apply on the affected plants– Apply on the foliage of the affected tomato plants. Reapply as required as it can degrade in sunlight.

Here is a useful video on using Bt spray:

Method 2- Sprinkling DE powder

Diatomaceous earth powder (DE) consists of a fossilized exoskeleton of unicellular algae. It can be used to control tobacco hornworms by desiccating their natural juices.

It is non-toxic to children or pets.

  • Sprinkle DE powder– Purchase food-grade DE powder and sprinkle them on the plants and around the base of the plants. You may wear a dust mask to avoid inhaling the powder
  • Reapply the powder– Reapply as required or after heavy rain.

Physical Ways To Control Tobacco Hornworm On Tomato Plants

The most effective physical method to reduce the population of tobacco hornworms is handpicking and destroying them. It is effectively picked during the nighttime.

Method 1- Handpick Tobacco Hornworm

Handpicking is an effective way to control tobacco hornworms in a small garden. It may require patience and time to look for these pests.

  • Look for the tobacco hornworm– Inspect the plants for feeding damage on the foliage. You may also shake the plants well to dislodge any larvae. You may spray water on plants to easily spot the pests.
  • Handpick the hornworms– Handpick the worms from the plants and submerge them in soapy water or feed them to a chicken.

Chemical Ways To Control Tobacco Hornworm On Tomato Plants

There are many organic and chemical insecticides available commercially for controlling tobacco hornworms in home gardens.

Take care in choosing one as few chemicals may harm the beneficial insects.

Method 1- Spray Spinosad Solution

Spinosad is an insect control agent that can be used to control tobacco hornworms in home gardens. It works by disrupting the nervous system of pests.

  • Purchase spinosad solution– Purchase spinosad solution and dilute it according to the manufacturer’s instructions. Transfer to a spray bottle
  • Spray on the affected area– Spray on the affected foliage to get rid of the tobacco hornworm. You may reapply as required according to the severity of the infection.

Check out this video to use the spinosad solution:

Method 2- Spray Insecticidal Soap

Insecticidal soaps have been used to control plant pests, including tobacco hornworms with no residual effect. It has minimal adverse effects on other organisms.

  • Prepare diluted soap solution– Mix about 2 ½ tablespoons of soap with a gallon of water. Transfer to a spray bottle.
  • Spray on the affected parts– Spray on the undersides of leaves and protected areas. Reapply as required because of the short residual action.

Here is a useful video on making and applying insecticidal soap:

How To Prevent Tobacco Hornworm In Tomato Plants?

The different preventive measures to control tobacco hornworms attacking tomato plants include tilling the soil to destroy pupae, encouraging beneficial predators in the garden, and practicing crop rotation.

Method 1- Alter The Garden Environment

Till or disk the soil in spring or fall after harvesting the plants. It helps in disrupting and destroying overwintering pupae and reducing their population.

Method 2- Encourage Hornworm Predators

There are many insects, including Lady beetles, paper wasps, and green lacewings, that prey on tobacco hornworms. Lady beetles and green lacewings feed on eggs, while paper wasps eat larvae.

Here is a video of wasps feeding hornworms:

Method 3- Practice Interplanting

You may try interplanting dill or basil with tomato plants. It helps in keeping the tobacco hornworms away from your tomatoes.

Marigold is also a good companion plant for tomatoes. It also attracts beneficial insects to the garden.

What Causes Tobacco Hornworm In Tomato Plants?

Tobacco hornworms attack tomato plants during humid environments and mid-summer.

It is also favored by untilled soil, and weed infestation as the hard-shelled brown pupae may overwinter in the soil.

Frequently Asked Questions

How to differentiate tomato hornworms and tobacco hornworms?

Both tomato and tobacco hornworms are closely related. Tomato hornworms have eight V-shaped white markings with no borders and black or blue horns. Tobacco hornworms have seven white diagonal lines with a black border and red horns.

What are the host plants of tobacco hornworms?

The host plants of tobacco hornworms include members of the Solanaceae family. It includes tomato, pepper, potato, eggplant, and different nightshade flowering plants. The primary host plant is tobacco plants.

Is tobacco hornworms poisonous?

No, tobacco hornworms are not poisonous to humans. Also, it will not sting and can be picked off tomato plants by hand without danger. It may look fierce with red horns but are harmless.

Can you use light traps to control tobacco hornworms?

Tobacco hornworm moths can be captured in light traps as it is attracted to light. Few studies have highlighted the use of these traps to suppress the hornworm population but it has not been proven practical. More studies are required to study its effectiveness.


I hope this guide has helped you identify, control, and prevent tobacco hornworms from damaging tomato plants. You may employ one or many methods to save the tomato plants.

Please do share if you have any other method to control tobacco hornworms.

Do share the guide with your friends and family!