Everything You Need To Know About Hornworm Caterpillars

If you have ever grown tomatoes, then you may have seen green-colored caterpillar pests. These are usually two main pest species, tobacco hornworms and tomato hornworms. These species can be found in southern Canada and various regions of the United States. These big, green insects can damage the tomato crop in no time. Not just that, but they feed on other plants in the nightshade family like tobacco, potatoes, bell peppers, and eggplants. Hornworm caterpillars blend easily with the green foliage and eat non-stop, while creating chewed and spotty fruits and leaves.

Hornworm caterpillars belong to the Sphingidae moth family. They are called hornworms due to their horn-like projections at the eighth abdominal segment’s end. These pests are known for their horns and large size than other species. Some, such as tobacco and tomato hornworms are the most common pests.


Hornworm caterpillars live according to a life cycle as follows:

  • In late spring, an adult moth lays eggs on the foliage’s undersides. These eggs will hatch within just a week. These adult moths are easy to recognize and commonly known as hummingbird moths or sphinx.
  • Caterpillar larvae hatch in spring and feed for 6 weeks before making a cocoon. In warm weather conditions, larvae might just burrow for about 3 weeks.
  • In spring, moths will show up and lay eggs for the second time. In warmer weather, there could be more than a single generation in a year.

How to Identify Hornworm Caterpillars

A tobacco hornworm caterpillar could be 5 inches in length, where you can be shocked while encountering one. It does the most destruction in the larval or caterpillar stage. It is a large green caterpillar with horn that stems from its rear. The caterpillar has eight stripes on the body in V shape. On the other hand, a tomato hornworm caterpillar comes from molted brown-gray moths.

The green caterpillar with horn blends incredibly well with the greenery of plants. You need to go for a regular patrol in order to find small caterpillars and hornworm eggs. Here are several cues of hornworm infestations:

  • Hornworms begin feeding on the plant’s top and thus, you have to look for missing or chewed leaves.
  • You need to look closely at leaves for black or dark green droppings left by the caterpillar feeding on the plant’s leaves. After that, look at the leaves’ undersides and you will most likely discover a hornworm there.
  • Also, look for missing leaves or wilted leaves hanging from the stem. You will find hornworms and their white cocoons nearby.

Difference Between Tobacco and Tomato Hornworms

There are some species of hornworms, which inhabit North American gardens, such as tobacco hornworms and tomato hornworms. Both kinds feed on typical garden plants like eggplants, peppers, potatoes, and tomatoes. Here’s how you can tell which caterpillar is which:

  • Tomato hornworms feature white V-shaped patterns, while tobacco hornworms feature parallel whitestripes.
  • Tomato hornworms do not have black spots along each stripe, while tobacco hornworms have.
  • A tobacco hornworm is a caterpillar with red horn, whereas tomato hornworms feature a black horn.

Damage Done by Tomato Hornworm

If you spot scarring on fruits, leaves with severe defoliation and large holes, devoured flowers, you may have tobacco or tomato hornworms. The fruit might be damaged by sunscald due to the reduced foliage cover.

Hornworm caterpillars

How to Control Hornworm Caterpillars

Handpicking: It is a great tactic to control hornworms if you own a small garden or have the patience and time. Hornworm caterpillars cannot bite or sting. If you are nauseous about beating these big insects, you can drop them into soapy water.

Insecticides: If your garden area or the population of hornworms is too big, it is best to go with insecticides. Gardeners can choose organic ones, such as Bt (Bacillus thuringiensis). This bacterium acts as a poison on several larval insects, but does not harm animals or other plants. To work effectively, caterpillars need to ingest it. So, you have to reapply to plant foliage after rain.

Insecticidal soaps: They are perfect for killing hornworm caterpillars. However, the pests should come in contact with this substance.

How to Prevent Hornworm Caterpillars

  • At the end and beginning of every gardening season, you need to till soil for destroying overwintering larvae. This helps to cause about 90% mortality.
  • You should keep wasps all around. Most species are beneficial as they feed on hornworm caterpillar and act as biological controls. You might have come across hornworms with wasp larvae attached. They look like grains of rice and continue to feed for some time and will soon succumb to the hitchhikers. So, you should leave these hornworms alone and let them carry out the life cycle. Alternatively, you can remove the infected hornworms and keep them far away from the garden. In this way, the wasps will do the job, but the hornworms would not damage the crops. Check out this video to see how this process occurs.
  • Other insects like green lacewings and ladybugs may also feed on hornworm eggs or small hornworms.
  • For keeping hornworm caterpillars away from the plants next year, you should try interplanting basil or dill, or marigolds as an incredible companion plant.


So, this is everything that you should know about hornworm caterpillars. The two most common species of hornworms are tomato hornworms and tobacco hornworms. You will most likely find these caterpillars on plants like tomatoes, potatoes, eggplants, bell peppers, and tobacco. If you spot them in your garden, some amazing ways to get rid of these insects are handpicking, using insecticides, and insecticidal soaps. You can also prevent them from manifesting in your garden in different ways. Share this article with other garden lovers and share your valuable comments in the section given below!

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