Knowledge from Olle Garden Bed: 3 Types of Worms That Eat Tomato Plants

Tomatoes are a delicious snack and a tasty target for worms! Discover the worms that are attacking your garden and how to get rid of them. The following content also has some reference value for raised garden beds.

Tomatoes reign as the king of cooking and are a primary ingredient in many dishes. The taste and freshness of homegrown tomatoes are unmatched. It's no wonder that various types of worms attack tomatoes, feasting on their juicy flesh and tender core. These tiny creatures feed on their leaves, flowers, and fruits, severely affecting your precious tomato crop.

Therefore, it's essential to understand which worms can prey on your tomato plants and how to repel them.

Hornworms

Hornworms can be disastrous for your tomato crops as they continuously feed, chewing on leaves and fruits. They also prey on other members of the nightshade plant family, such as potatoes, eggplants, and peppers.

Two types of hornworms typically attack tomato plants: tomato hornworms and tobacco hornworms. They cause similar damage but have different appearances.

Hornworm eggs are spherical, smooth, and extremely tiny, measuring only about 1/16 inch wide. They start off light green and turn white before hatching.

Hornworms can grow quite large as they are a type of caterpillar. They can reach up to 5 inches in length and are pale green, making them difficult to spot among the foliage.

Tomato hornworms have eight V-shaped stripes on their bodies and a straight, black, horn-like protrusion on their tails. Tobacco hornworms have parallel white stripes with black spots along the stripes. They also have a red horn extending from their rear.

Damage

Hornworms voraciously feed on the leaves, leaving behind large holes or defoliated areas. Their infestations typically begin in midsummer and can persist throughout the growing season. They can also eat flowers and feed on developing fruits, leading to open scarred areas on the surface.

While they are more prone to damaging leaves than fruits, defoliation can result in sunburned tender tomato skins. When tomato fruits are exposed to excessive sunlight, they develop a condition known as sunscald. This condition manifests as yellow spots on the side of the fruit facing the sun in green and ripened fruits. Over time, the spot turns into a white, blister-like appearance.

Control

Since hornworms are not hazardous, you can easily handpick them from the plants and drop them into soapy water to kill them. Handpicking is an excellent control strategy for small gardens but requires time, patience, and vigilance.

You can use insecticides in severe infestations, but this should be a last resort as they contain harmful chemicals that require thorough washing before consuming the fruits. Organic pesticides like Bt (Bacillus thuringiensis) effectively eliminate hornworms without negatively impacting surrounding plants or animals. Pesticides work upon ingestion and may need reapplication after rainfall.

You can also introduce natural predators of hornworms into your garden, such as ladybugs, braconid wasps, and green lacewings. Purchase or plant flowers like marigolds, catnip, or daisies that attract these beneficial insects.

Another effective method is practicing companion planting. Add plants like basil that deter hornworms with their scent.

Cutworms

Cutworms are another serious pest that troubles tomatoes. There are different types of cutworms, such as black cutworms, bronze cutworms, and dirty cutworms. They may have varying appearances, but they all cause similar damage by cutting down plants. Apart from tomatoes, they also enjoy feasting on many other plants, such as beans, asparagus, cabbage, potatoes, peas, and lettuce.

Identification

Cutworms are smooth-bodied when fully mature and measure about 2 inches long. Different species can have different appearances and colors like brown, tan, pink, green, gray, and black. Some are solid, while others have spots or stripes. The larvae can be dull or glossy.

However, all cutworms share a common characteristic that makes them easy to identify. When disturbed, these worms curl up into tight "C" shapes.

Damage

Cutworms are most active during the evening and night, hiding in plant debris during the day. They wrap their bodies around the stems and then feed on them, causing the plants to be cut off above the soil surface.

Seedlings are most vulnerable to cutworm damage as their stems are tender. However, they can also feed on leaves and fruits later in the season, leaving behind chewed foliage and fruits.

Control

Monitor tomato plants and look for plants cut off near the soil level or wilted stems, as these are clear signs of cutworm activity. The best time to spot cutworms is during the evening and night when they are most active.

To determine the presence of cutworms, gently slide your hand over the soil. Carefully inspect the area within a 1-foot radius around affected plants, particularly soil clumps and other hiding spots. If cutworms are present, they will instinctively curl up into their distinctive "C" shape when disturbed.

Once you find them, crush them or drop them into soapy water to kill them. You can also use organic insecticides, which are most effective against the larvae.

Prevention

There are several methods to protect your tomato crops from cutworms:

Place a cardboard or aluminum collar around seedlings to prevent cutworms from cutting them down. Wrap a material (collar) around the stem, extending it about 1 to 2 inches deep and 2 to 3 inches wide around the plant. This prevents the worms from crawling up and chewing on the stem.

Till the soil in the fall and before planting to eliminate any overwintering larvae.

Clear weeds near the planting area as they can serve as alternate hosts.

Remove plant debris that can serve as egg-laying sites.

Tomato Fruitworms

Tomato fruitworms, also known as corn earworms and cotton bollworms, are another type of worm that enjoys feeding on juicy fruits. They are difficult to detect, so it's crucial to monitor your tomato plants diligently.

Identification

Tomato fruitworms come in different colors, ranging from yellow-green to black, with a brownish head. They measure about 1.5 to 2 inches in length when fully mature and have spiky projections and dark and light-colored stripes on their bodies.

The eggs are white, spherical, slightly flattened, and about half the diameter of a pinhead. When hatched, the larvae are white with a black head and noticeable hairs.

Damage

Tomato fruitworms typically enter tomatoes during the larval stage. They bore into the fruits from the stem end when the fruits are only 2/3 to 1 inch wide, leaving behind a visible black hole. However, they can also feed on ripe tomatoes.

The worms feed on the interior of the tomato, creating a watery cavity with discarded skins and feces. As they grow, they may move from one fruit to another. Damaged fruits also ripen prematurely.

Control

Since tiny larvae develop inside the tomatoes, they are challenging to detect and control. If you find infected fruits, remove and dispose of them to prevent insects from moving to other fruits. You can use the pesticide Bt during the warmest weather to kill the larvae. Avoid planting tomatoes near corn, as they are both susceptible to these worms.

Worms' Feasting

Growing tomatoes at home isn't overly challenging as long as you stay vigilant and regularly monitor your plants for any pesky pests. Most worms that attack tomatoes can be controlled in this manner, preventing them from causing severe damage to your crops. And most importantly, all your efforts are worthwhile when you enjoy a bountiful harvest of delicious tomatoes!