What are the big green worms on tomato plants?

If you've ever grown tomatoes, you may have encountered big green worms munching on your plants. These worms can quickly wreak havoc on your tomato harvest, and it's important to understand what they are and how to deal with them.

Types of worms

There are two types of worms that commonly feed on tomato plants: tomato hornworms and tobacco hornworms. Both of these pests can grow up to four inches long and have a similar appearance, making it difficult to differentiate between the two.

The tomato hornworm has eight V-shaped white markings on each side of its body and a black horn on its rear end, while the tobacco hornworm has seven diagonal white stripes and a red horn.

Life cycle

Hornworms typically begin their life cycle as eggs laid on the leaves of tomato plants. After hatching, the worms feed on the leaves and gradually grow larger. As they mature, they can consume entire leaves and even the fruits of the tomato plant.

After feeding for several weeks, the hornworm will burrow into the soil and pupate, eventually emerging as a moth. The moths mate and lay eggs to begin the cycle all over again.

Damage to plants

Hornworms can cause significant damage to tomato plants, eating away large chunks of leaves as well as entire fruits. This can lead to stunted growth, reduced yields, and in severe cases, the death of the plant.

Signs of hornworm damage include holes in leaves, missing or dropped fruit, and black droppings (frass) near the affected area.

Control methods

Fortunately, there are several effective ways to control hornworms and prevent them from damaging your tomato plants. One method is to physically remove the worms from the plant and dispose of them in a sealed container or bag.

You can also attract natural predators of hornworms, such as parasitic wasps and braconid wasps, which lay eggs inside the hornworms, eventually killing them. These wasps can be attracted with plants such as dill and parsley.

Another option is to use insecticides specifically formulated for hornworms, such as Bacillus thuringiensis (Bt), which is a natural bacteria that poisons the worms without harming other beneficial insects.

Prevention

The best way to prevent hornworm infestations is to maintain healthy tomato plants. This can be achieved by providing adequate water and nutrients, using mulch to keep the soil moist, and pruning any damaged or diseased leaves.

You can also plant companion plants that repel hornworms, such as marigolds, or use row covers to physically prevent the moths from laying eggs on your plants.

Conclusion

Hornworms can be a nuisance for tomato growers, but with the right methods of prevention and control, you can keep them at bay and enjoy a bountiful tomato harvest.