Growing tomatoes means contending with various organisms that view the plants as a food source. Accurately identifying the specific culprit is crucial, as different pests leave distinct signs requiring varied management approaches. Damage ranges from outright consumption of leaves and stems to subtle draining of the plant’s internal resources. Distinguishing between chewing insects, sap-suckers, or mammals is the first step toward protecting the harvest. Diagnosis depends on careful observation of the nature, location, and scale of the feeding evidence.
Pests That Cause Defoliation and Stem Damage
Rapid destruction to tomato foliage is often caused by large, chewing insect larvae. The Tomato Hornworm, the caterpillar stage of a sphinx moth, can defoliate entire branches in a single day. These caterpillars grow up to four inches long and are pale green with white, V-shaped markings, blending seamlessly with the foliage. A tell-tale sign is the accumulation of large, dark green, pellet-like droppings, known as frass, found below the feeding site or at the base of the plant.
Another common threat comes from the Flea Beetle, which targets plants early in the season when they are most vulnerable. These tiny, dark-colored beetles measure less than an eighth of an inch and jump away quickly when disturbed. Adult beetles create numerous minute, round holes across the leaves, a pattern described as “shot-hole” damage. While mature plants tolerate light feeding, a heavy infestation can severely stunt the growth of young tomato seedlings.
Small Pests That Drain Plant Vitality
A group of tiny insects causes damage by extracting the plant’s internal fluids. Aphids are small, pear-shaped insects that cluster on tender new growth or the undersides of leaves, using piercing-sucking mouthparts to siphon sap. This feeding drains the plant’s vigor, leading to distorted, curling leaves and stunted growth. Aphids also excrete a sticky, sugary liquid called honeydew, which encourages the growth of black, superficial sooty mold.
Spider Mites are sap-suckers difficult to see without magnification. Their feeding causes a characteristic symptom called stippling, appearing as tiny pale yellow or white speckles on the upper surface of the leaves. As the infestation progresses, leaves may take on a bronzed appearance, eventually yellowing and dropping off. A definitive indicator is the fine, silky webbing they spin, particularly around growing tips and on the undersides of leaves.
Whiteflies are sap-sucking pests identified by the small, white, moth-like adults that fly up in a cloud when the plant is disturbed. Whiteflies feed on the undersides of leaves and produce sticky honeydew, which attracts sooty mold. Heavy feeding leads to leaf yellowing and a general decline in plant health, sometimes transmitting plant viruses.
Larger Predators That Consume Fruit and Whole Plants
Larger vertebrate animals consume ripe fruit or sever entire plants. Squirrels and chipmunks frequently target developing tomatoes, often taking a few bites out of a single fruit before discarding it and moving to the next. This partial consumption and waste of multiple tomatoes is a hallmark of rodent feeding behavior. These small mammals may also dig in the soil near the plant, disturbing the root system.
Deer cause extensive damage to the upper portions of the plant due to their height. They lack upper incisor teeth, resulting in a ragged, torn appearance on consumed stems or leaves. This damage is typically found a foot or more above the ground. In contrast, Rabbits feed closer to the soil, leaving clean, angled cuts on young stems and lower leaves, as their sharp incisors act like tiny shears.
Voles rarely feed on the above-ground parts of the plant, focusing instead on the roots and lower stems. Their presence is indicated by a decline in plant health, sometimes leading to the plant’s collapse, and by small tunnels near the base. Voles can chew through the bark near the soil line, known as girdling, which cuts off the flow of nutrients and water to the rest of the plant.