Tomato Caterpillar: [How to Identify and Fight It]

Manduca quinquemaculata or tomato caterpillar is a five-spotted worm, or brown and gray hawk moth of the family Sphingidae.

The tomato caterpillar, often known as the tomato hornworm, can be a significant pest in gardens and orchards; It gets its name from a dark projection on its rear end and from being a common host on tomato plants.

Tomato hornworms are closely related to the Manduca tobacco hornworm (confusing many times).

This confusion arises because the caterpillars of both species have similar morphologies and feed on the foliage of various plants in the Solanaceae family, so either species can be found on tobacco or tomato leaves.

Characteristics of the tomato caterpillar

  1. Tomato hornworms are very large caterpillars with a horn-like tail.
  2. His favorite plant is the tomato.
  3. Hornworms chew through leaves and can completely defoliate plants.
  4. They can also chew holes in the fruit.

Tomato hornworms are known to feed on various plants in the nightshade family, commonly feeding on tomato, eggplant, pepper, tobacco, moonflowers , and potato.

Females prefer to oviposit on young leaves near the stem of host plants, and early-stage caterpillars can often be found here during the day.

In the afternoon or early morning when the sunlight is less direct, the caterpillars will feed on the most distal leaves.

Adult caterpillars or worm

Adults feed on nectar from flowering plants such as Datura meteloides, Oenothera caespitosa, and Mirabilis multiflora.

Most of the food plants they target have large , white, fragrant flowers.

Interactions with host tomato plants

Sparrowhawks, including M. quinquemaculata, are the main pollinators of D. meteloides.

The length of the moth’s proboscis (about 10 cm), which is an elongated tubular mouthpart used for sucking and feeding, is efficient in retrieving nectar from flowers.

In addition to being a host plant for M. quinquemaculata, D. meteloides has also been used by humans for its opioid effects. D. meteloides contains tropane alkaloids, which are present throughout the plant, including the flowers.

These alkaloids have an intoxicating effect on the moth, which displays erratic flight patterns as well as uncoordinated and often unsuccessful landing attempts after consuming the nectar.

Despite the damage caused by the nectar, the moths have been observed to return to the flowers and consume more nectar. It has been hypothesized that the «eared» nectar offers moths a reward that goes beyond nutrients.

Both Mirabilis multiflora and Oenothera caespitosa also depend on hawkmoth pollinators for their pollination.

The tomato caterpillar has been found to feed first on Oenothera caespitosa and only later visit Mirabilis multiflora, indicating a preference for the former.

tomato caterpillar life cycle

  1. Tomato hornworms survive the winter as pupae, emerging as adult moths in the spring.
  2. After mating, females lay oval, smooth, light green eggs on the upper and lower leaf surfaces.
  3. The caterpillars hatch, begin feeding, and are fully grown in three to four weeks.
  4. Mature caterpillars drop plants and burrow into the soil to pupate.
  5. The moths emerge in two weeks to start a second generation in midsummer.
  6. Second-generation moths lay eggs on host plants, such as tomato.
  7. The caterpillars feed until late summer or early fall and then pupate.
  8. The pupae remain in the soil through the winter.

Identify the tomato hornworm: What damage does it cause?

Hornworms can be up to 12 centimeters long, so they can impress you the first time you encounter them.

They do the most damage at the caterpillar or larva stage. They are pale green with black and white markings, as well as a horn-like protrusion coming out of their butt. (Don’t worry, they are not able to sting or bite!)

The caterpillar also has eight V-shaped stripes on its green body. Tomato hornworms come from a grayish-brown mottled moth (see photo, above).

The larvae blend very well with the greenery of the plant. Get used to a daily patrol, looking for worm eggs and small caterpillars. Here are some signs of infestations:

  1. Hornworms tend to start feeding at the top of the plant; look for chewed or lost leaves.
  2. Look closely at the tops of tomato leaves for dark green or black droppings left behind by larvae feeding on the leaves.
  3. Then look at the underside of the leaves. You will likely find a hornworm.
  4. Look for stems that are missing some leaves and withered leaves that are hanging down. You may find white cocoons and their worm hosts around.

The tomato is usually their preferred host, but they have also been found on potatoes, aubergines and peppers.

There are many herbs that serve as alternate hosts, including horsegrass, jimsonweed, and belladonna. Large numbers of caterpillars may appear in home gardens and can rapidly defoliate plants.

Tomato hornworm caterpillars start feeding on the leaves on the tops of plants. The caterpillars blend in with the leaves and may not be noticed until most of the damage is done.

As they feed, they create dark green or black droppings that are clearly visible. Older tomato hornworms can destroy several leaves as well as the fruit.

As they grow, the amount of defoliation increases. The last stage of the caterpillar consumes almost as much as all the younger stages combined.

How to fight tomato caterpillar

  1. Check the plants for tomato hornworms at least twice a week during the summer.
  2. Remove weeds to reduce the number of sites where worms can lay eggs.
  3. Cultivate the soil after harvest to destroy caterpillars and pupae.

Get rid of tomato plant worms

This is the most effective means of controlling this pest. Tomato hornworms are easy to find due to their large size.

You can spray with potassium soap or neem oil to kill them once identified.

Natural enemies of the tomato hornworm

A green caterpillar on a green leaf with several white cocoons on its back is parasitized hornworm. There are many natural enemies of the tomato hornworm.

Predatory insects in general, such as lady beetles and green pupae, often feed on the egg stage and young caterpillars.

Another important predator is the paper wasp, Polistes spp. This common wasp feeds on many types of caterpillars including those found in gardens.

Tomato hornworms are also parasitized by various insects. One of the most common is a small braconid wasp, Cotesia congregatus. The larvae that hatch from the wasp’s eggs are put into the hornworm.

Wasp larvae feed inside the worm until the wasp is ready to pupate. The cocoons look like white rice protruding from the worm’s body.

If you see this happening, leave the worms in the garden to allow the adult wasps to emerge. These wasps kill the worms as they emerge from the cocoons. The wasps then seek out other worms to parasitize.

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