What Are Red Worms on Tomato Plants?

Tomato Fruitworm

• The tomato fruit worm is a small caterpillar that hatches out creamy white with a black head. As it ages, this caterpillar can turn a variety of colors, ranging from yellow-green through red and almost black. They also may have white lines along their body and patches of stubby spines. Tomato fruitworms enter the plant's stem end and eat the fruit from inside, resulting in a damaged tomato filled with shed skins and waste. Control tomato fruitworms by encouraging natural parasites or spraying with Bacillus thuringiensis bacterial pesticide.

Tobacco Budworm

• Tobacco budworms are also known as geranium budworms. They feed on the petals and buds of a wide range of plants. The larval form of this insect is relatively small and usually dark in color. Light brown, red and green larvae may also be seen on plants. These caterpillars take about a month to mature, producing a second generation later in the season. Check tomato buds for small holes and treat plants with Bacillus thuringiensis insecticides or resistant plants. Pyrethrin-based chemicals are the most effective conventional pesticides, but do not provide easy control.

Tomato Hornworm

• These large caterpillars are the larvae of sphinx moths. These showy moths resemble hummingbirds while in flight. Their larvae are usually green, but may also come in reddish or purplish brown forms. Hornworms feed primarily on tomato and tobacco plants and are voracious eaters, removing large quantities of leaves in a single day. Bacterial controls or conventional insecticides both work against these pests.

Considerations

• While reddish caterpillars cause serious damage to tomato plants, smaller infestations may not pose a serious problem. The adult moth form of some species, such as the sphinx moth, provide pollination services for other plants and are an important part of the natural environment. When tomato caterpillar pests aren't causing a major problem, it may be best to leave them. To control small populations without pesticides, remove the insects by hand. According to the Colorado State University Extension, most tomato caterpillar pests are more active in the outside leaves near dawn and dusk and are easier to remove at these times.