Tomato Plant Insect Pests: Tips For Treating Pests On Tomatoes

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Snail On Tomato Plant
Image by Dmitriy Sidor

What is eating my tomatoes? Some gardeners practically swoon over a perfect tomato plant. Although there is perfection in nature, the fact is that our cultivated tomatoes rarely achieve this lofty goal. Any number of tomato plant insect pests lurk right around the corner ready to take down your prized heirlooms. Even if tomato insect damage is nominal, the pests themselves often are vectors for disease. So, it is imperative that you recognize tomato insect damage and learn about treating pests on tomatoes.

Tomato Bug and Insect Pests

There are many pests of tomato plants – these are some of the most common.

Aphids

Common tomato pests, and pests of just about everything else (at least in my garden), are aphids. Aphids populate new stems and the undersides of leaves leaving sticky honeydew in their wake. They suck the nutrient-rich sap from the plant. The honeydew attracts other pesky insects.

A strong stream of water can wash them off but it might damage the tomato. You can also spray with an insecticidal soap or garlic oil spray to reduce the population or encourage natural predators, such as lacewings or ladybugs, who will only gladly help reduce their numbers.

Blister beetles

Blister beetles also like to dine on your tomatoes and if there are many of them, can defoliate a plant. These medium-sized black, red, gray, or striped beetles eat grasshopper eggs, which can be a good thing, but their rampant appetite for the tomato foliage is less desirable.

Handpick these pests from the plant and drop them into a bucket of soapy water.

Cutworms

Another tomato plant pest is a smooth underground operator. The cutworm is a one-inch (2.5 cm.) caterpillar that curls into a C-shape under the soil that can eviscerate young plants at the surface.

Use a collar made of paper cups with the bottoms cut out or a 2-inch (5 cm.) portion of a toilet paper tube pushed down around the base and just under the soil surrounding the roots of the plant. This can keep the worms from gnawing at the tomato. Shallow tin cans, like tuna fish cans, with the bottoms removed will work the same way. Blood meal scattered around the plant will also repel cutworms. Also, dig up the garden in the early spring to expose the rascals and kill them off by freezing or starving them.

Flea beetles

Flea beetles are yet another insect pest of tomato plants. These tiny metallic, dark brown beetles eat holes in the leaves, which will eventually stunt or even kill young plants.

Remove weeds around the plants where the beetles nest and spray the tomatoes with an insecticidal soap. Basil planted nearby is also said to repel them.

Leafhoppers

Leafhoppers also like to munch on your tomatoes. These wedge-shaped, pale green hopping insects feed on the sap and cause the leaves to curl, but that isn’t the real problem. Leafhoppers transmit pathogens that can cause devastating plant diseases.

As with aphids, a strong blast of water can remove them or spray them with an insecticidal soap or organic pesticide, or dust with sulfur. Also, try covering the plants with a floating row cover.

Spider mites

Tomato spider mites are tiny insects that produce webbing that makes the plant look as if it is covered in white mold. Their favorite areas are leaf tips and blossom buds, but they feed on the sap of the leaves as well.

Keep the tomato plant consistently watered, which reduces the incidence of these mites, and avoid nitrogen fertilizer. Use predator mites to aid in controlling the pest mites. Wash the plant with mild soap and rinse well to remove some of the mites and prune out heavily infested areas.

Nematodes

Nematodes are microscopic worms that cause odd swelling on roots, yellow foliage, wilting, and stunting in plants. They are easily spread on your garden tools and boots.

The key to treating these pests on tomatoes is sanitation. Sterilize your tools, boots, and gloves. Clean potentially contaminated pots with a 10% bleach/water solution. Remove and destroy all infected plants.

Remove as much of the infected surrounding soil as possible. To treat the soil, plant the marigolds, and then when they are done flowering, dig them under. The chemicals that are released are abhorrent to nematodes. Also, only plant nematode-resistant tomatoes, which will have an “N” listed under the plant name.

Slugs and snails

Slugs and snails are ever-present in my neck of the woods. They will eat both foliage and fruit near the soil surface, leaving holes in tomatoes and leaves.

Handpick these slimy pests or make traps with shallow pans of beer placed near the plants. If you would rather drink your beer, use one tablespoon (14 mL.) of flour, 1/8 teaspoon (0.5 mL.) of yeast, and one cup (236 mL.) of water. Commercial baits work as well. Also, to discourage snails and slugs, mulch around the tomatoes with coarse hay or place rough rocks around plants.

Tomato fruitworms

Tomato fruitworms, AKA corn earthworm and cotton bollworm, are 2-inch (5 m.) long, striped yellow to gray worms. They tunnel into the fruit and feed on the leaves of tomatoes.

You can handpick both larvae and eggs to reduce the population. Also, till the soil in the fall to expose the pupae where predators or cold will kill them off. Bacillus thuringiensis is also an effective control for these and any other caterpillar or worm pest, as is the use of garlic spray.

Whiteflies

Whiteflies primarily affect greenhouse or houseplant-grown tomatoes.

Spray foliage in the morning to disrupt their feeding pattern and dislodge eggs, nymphs, and pupae. Lower temps will also reduce whitefly activity. A natural predator, Encarsia formosa can reduce populations.

Wireworms

Wireworms are light brown, hard-bodied worms. They are the larval stage of the click beetles and feed on underground stems and roots, which stunt the plant and reduce yield. Till the soil to expose them to birds and other predators and apply beneficial nematodes and rotate the crops each year.

As you can see, there is a multitude of pests that can affect tomatoes. Identifying and treating pests on tomatoes is the key to squelching the problem as soon as possible. Plant pest-resistant varieties, if possible; practice crop rotation; keep the garden and equipment sanitary; stake and mulch tomatoes to keep them from coming into contact with the soil and use well-draining soil amended with plenty of organic matter. Inspect your seedlings and transplants and dispose of them if you see any signs of infestation or disease.

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