“Tomato bug” isn’t one specific insect. It’s a catch-all term gardeners use for several pests that attack tomato plants, with hornworms, stink bugs, and leaf-footed bugs being the most common culprits. Identifying which one you’re dealing with is the first step toward protecting your crop.
Tomato Hornworms
Hornworms are the pests most people picture when they say “tomato bug.” These caterpillars grow up to 3.5 inches long, are bright green (sometimes reddish-brown), and sport a distinctive horn on their rear end. Two species attack tomatoes: the tobacco hornworm, which has seven diagonal white stripes on each side, and the tomato hornworm, which has eight V-shaped markings. Both do the same kind of damage.
Hornworms are voracious. They strip entire leaves and small stems from your plants, and they’ll chew large chunks out of green fruit. Because they’re so well camouflaged against the foliage, you’ll often notice their damage before you spot the caterpillar itself. The telltale sign is large black or green droppings scattered on the ground beneath your plants. If you see those, look up: the hornworm is almost certainly on a branch directly above.
Damage peaks in midsummer, with a possible second wave in late summer. Warmer inland areas tend to see worse infestations. The adult form is a large moth with a wingspan up to 5 inches, but only the larval (caterpillar) stage causes damage. After feeding, larvae burrow into the soil to pupate, and adult moths emerge the following spring to lay eggs singly on tomato leaves, starting the cycle over.
Stink Bugs and Leaf-Footed Bugs
Stink bugs are shield-shaped, green or brown, and about 3/4 inch long. Their nymphs are green with orange and black markings. Leaf-footed bugs are closely related, slightly more elongated, and named for the flattened, leaf-like expansions on their hind legs. Both feed the same way: they pierce tomato fruit and buds with needle-like mouthparts and suck out plant juices.
The damage depends on when they feed. On small, developing fruit, their feeding can cause the tomato to abort entirely. On medium-sized fruit, you’ll see depressions or discoloration that become more obvious as the tomato grows and ripens. On mature fruit, the damage is usually just slight surface discoloration. When these bugs feed, they can also introduce yeasts into the fruit, causing additional discoloration patterns. Stink bugs also pierce flower buds, causing them to drop before they set fruit.
Stink bugs are considered one of the two most important tomato pests (alongside fruitworms) and are notably harder to control than caterpillar pests.
The Tomato Mirid Bug
Less well known but increasingly problematic, the tomato mirid is a small, slender green bug that’s both predator and pest. It uses a needle-like mouthpart to feed on whiteflies and other small insects, which makes it beneficial in some situations. The problem arises when prey runs out. Without enough insects to eat, mirids turn to the tomato plant itself, piercing stems, flowers, and fruit. This feeding creates distinctive brown rings on the stems that eventually turn into dead, necrotic tissue. In greenhouse tomato production, mirids can cause significant crop losses when their populations outpace the pest insects they’re supposed to be eating.
How to Spot the Damage
Each pest leaves a different signature:
- Stripped leaves and large fruit scars: Hornworms. Look for big black droppings on the soil below.
- Dimpled, deformed, or aborted fruit: Stink bugs or leaf-footed bugs. Fruit that drops early or develops sunken spots as it ripens points to piercing-sucking insects.
- Brown rings on stems and flowers: Tomato mirid bugs, especially in greenhouse settings.
- Curled or yellowed leaves with tiny insects underneath: Aphids or whiteflies, which are secondary tomato pests but still common.
Companion Planting for Prevention
Planting the right neighbors around your tomatoes can reduce pest pressure before it starts. French marigolds are the most studied companion plant for tomatoes. Their roots suppress root-knot nematodes, a common soil pest that stunts tomato growth. Research has shown that interplanting marigolds with tomatoes can increase fruit yields by up to 50%. Marigolds also help reduce humidity around plants, which lowers the risk of fungal diseases like early blight.
Basil is another strong companion. Studies show it can increase tomato plant size, fruit yield, and root growth while deterring hornworms. One study found that basil planted in a 1:1 ratio with tomatoes boosted plant vigor more effectively than chemical fertilizer. Other aromatic herbs like thyme, parsley, sage, oregano, and cilantro emit strong scents that repel whiteflies, beetles, aphids, and thrips. If you let these herbs flower, they’ll attract beneficial insects, including parasitic wasps that prey directly on hornworms, as well as ladybugs and lacewings that eat aphids.
Removing Pests by Hand
For small gardens, handpicking is the most immediate solution. Hornworms are large enough to grab and drop into a bucket of soapy water. Check your plants in the early morning or evening when the caterpillars are more active and easier to spot. Look on the undersides of leaves and along stems near the top of the plant. If you see a hornworm covered in small white cocoons, leave it alone. Those cocoons belong to parasitic wasps that have already killed the caterpillar and will soon emerge to hunt more hornworms.
For aphids and other small soft-bodied pests, a forceful spray of water from a garden hose can knock them off the plants. This won’t work for stink bugs, which are tougher and more mobile, but repeated water sprays can keep aphid populations from building up.
Organic Sprays That Work
For caterpillar pests like hornworms and fruitworms, two organic options stand out. Products containing Bt (a naturally occurring soil bacterium) are effective when caterpillars eat treated leaves. Bt is slow-acting and works best when caterpillars are still small, so apply it as repeated sprays early in an infestation. Spinosad, derived from a different soil microbe, is considerably more effective against caterpillars than Bt and also controls thrips and leaf miners. It has extremely low toxicity to mammals and birds, and a pre-harvest interval of just one day, meaning you can spray today and pick tomatoes tomorrow. Apply spinosad when pollinators aren’t actively foraging, since it’s toxic to bees while still wet but relatively safe once dry. To prevent resistance, limit applications to two or three consecutive sprays, and no more than three times within a 21 to 30 day window.
Neem oil controls soft-bodied insects like aphids, whiteflies, and mites, and also has some antifungal properties. A related neem-derived compound acts as a growth disruptor for sucking insects, preventing immature pests from developing normally. It’s slow-acting and needs to be applied early, when pest populations are still low.
Stink bugs are the toughest to manage organically. Their numbers and damage can be reduced with timely, repeated sprays of pyrethrin (a plant-derived insecticide) combined with neem-based products, but complete control isn’t realistic. Consistent scouting and early intervention give you the best results.