The squash bug (Anasa tristis) is a common pest that concerns many home gardeners, especially when observed near tomato plants. The simple answer is no; they are not considered a pest of tomatoes and rarely feed on them. If you are finding damage on your tomato plants, a different insect is almost certainly the cause. This distinction is important for proper pest management, as squash bug control methods will not help protect your tomato crop.
The Squash Bug’s Primary Host Plants
The squash bug is specialized, feeding almost exclusively on plants belonging to the Cucurbitaceae family, often called cucurbits. This group includes common garden vegetables such as squash, pumpkins, zucchini, melons, and cucumbers. They use piercing-sucking mouthparts to penetrate plant tissue and withdraw sap.
This feeding depletes the plant’s vascular system of water and nutrients, causing initial damage symptoms. Leaves develop yellow spots that eventually turn brown and become brittle. Heavy infestations can sever the xylem vessels, leading to rapid wilting of the vines, a symptom sometimes called “Anasa wilt.” The bugs can also transmit the bacterium responsible for cucurbit yellow vine disease, which can be fatal to the host plant.
Identifying the Real Tomato Pests
If you observe damage on your tomato plants, the true culprit is likely one of several common garden pests that specifically target the Solanaceae family.
One of the most destructive is the tomato hornworm, a large green caterpillar that can rapidly defoliate a plant. The presence of large, dark green or black pellets, known as frass, on the leaves or ground is often the first sign of this pest.
Another frequent problem involves sap-sucking insects like aphids or spider mites, which cause very different symptoms. Aphids are small, soft-bodied insects that cluster on new growth and the undersides of leaves, extracting plant fluids. This often causes the leaves to curl or become stunted, and they also secrete a sticky substance called honeydew.
Spider mites are nearly microscopic arachnids that feed by piercing the surface cells of the leaves. Their feeding results in a fine stippling—tiny white or yellow dots—on the foliage. In severe infestations, fine silk webbing may be draped across the leaves and stems, which can severely stunt the plant’s growth.
Management of Squash Bugs Near Vegetable Gardens
Since squash bugs pose a threat to nearby cucurbit crops, managing their population is important for garden health.
A highly effective control method involves hand-picking, which should be done early in the morning when the insects are less active. Adults and their grayish-white nymphs can be collected and dropped into a container of soapy water to drown them.
Inspecting the undersides of leaves for their distinctive bronze-colored, barrel-shaped egg clusters is also recommended. These eggs are often laid in an angular pattern along the leaf veins and should be scraped off or crushed to prevent a new generation from hatching.
Another simple technique is to place a board or flat stone near the plants. Adults will hide underneath it overnight, allowing you to check the trap in the morning and destroy the bugs found there.
Using floating row covers over young cucurbit plants can physically block the adult bugs from laying eggs early in the season. These must be removed when the plants begin to flower to allow for pollination. Sanitation is an important cultural practice, requiring the removal of old vines and garden debris in the fall, which eliminates overwintering sites.