The tomato pests worth worrying about are the ones that can strip a plant of leaves or hollow out fruit before you notice: hornworms, aphids, whiteflies, and fruitworms top that list. Spider mites and flea beetles matter too, mostly as stress multipliers when a plant is already struggling. Catching an infestation early and treating only what actually needs treating, instead of spraying everything on sight, is what protects the harvest. This page covers identifying each pest, timing your checks to the plant’s own growth stages, and treating without killing off the beneficial insects doing free work in your garden.
Why this matters
A tomato plant can tolerate a surprising amount of chewing damage on its lower leaves without any real yield loss. What it cannot tolerate is losing leaf area during flowering and fruit set, when the plant needs every bit of photosynthesis to size up fruit. A hornworm that strips a branch bare in a couple of days, or an aphid colony that curls and weakens new growth, hits hardest exactly when the plant can least afford it. The timing of the damage matters as much as the amount.
Skip pest checks and you find out about a problem only once it’s visible from across the yard, which usually means it’s already past easy control. Handle it badly, meaning you reach for a broad-spectrum spray at the first sign of any insect, and you often make things worse: you kill the parasitic wasps and ladybugs that were quietly keeping aphids and hornworms in check, and the pest population rebounds harder than before. Untreated infestations also open the door to disease, since chewed and stressed tissue is easier for fungal and bacterial pathogens to colonize. If you’re also seeing spotted or yellowing leaves alongside insect damage, it’s worth comparing symptoms against the guide on tomato diseases before you assume it’s pests alone.
When to do it
Pest scouting isn’t a one-time task, it’s a habit that should run from the week after transplanting through the end of harvest, with the intensity changing as the plant moves through its stages. Right after transplant, watch mainly for cutworms and flea beetles, which target young, tender stems and leaves. Once the plant is established and putting on vegetative growth, aphids and whiteflies tend to show up on the undersides of new leaves and along stem tips.
The highest-stakes window is from first flower through fruit set. This is when hornworms do the most damage, because a plant that loses leaf cover right as it’s setting fruit can’t recover that lost capacity in time. It’s also when tomato fruitworms (sometimes called corn earworms) start looking for a place to lay eggs, so check the top growth and any flower clusters more closely once blossoms appear. Once fruit is sizing up, shift attention to the fruit itself, not just the foliage, looking for small entry holes or discoloration near the stem end.
A simple rule: check plants every few days during active growth, and check more often, ideally every day or two, from first bloom until you’re harvesting steadily. Early morning is the best time to look, since many pests are more visible and less active before the day heats up.
How to do it
Scout before you treat
Walk the row slowly and look at three places on each plant: the undersides of leaves, the growing tip, and any flower or fruit clusters. Turn leaves over with your fingers rather than just glancing at the tops. A flashlight helps even in daylight, because it throws shadows that make small insects and their eggs easier to spot against the leaf surface. Look for sticky residue (a sign of aphids or whiteflies), stippled or bronzed leaves (spider mites), ragged chewing damage (hornworms or beetles), and clustered white eggs on leaf undersides (several moth species, including the ones that become fruitworms).
Identify before you act
| Pest | What you’ll see | Where to look | First response |
|---|---|---|---|
| Hornworms | Large green caterpillars, dark droppings on leaves below | Mid to upper stems, often camouflaged | Hand-pick, check for white cocoons (parasitic wasp signs) before killing |
| Aphids | Small soft-bodied insects clustered on new growth, sticky residue | Undersides of young leaves, stem tips | Strong water spray, then insecticidal soap if it persists |
| Whiteflies | Tiny white insects that fly up when leaves are disturbed | Undersides of leaves | Yellow sticky traps, insecticidal soap on the undersides |
| Fruitworms | Holes in fruit near the stem end, caterpillars inside | Green fruit and flower clusters | Remove and destroy affected fruit, monitor flowers closely |
Once you know what you’re dealing with, match the response to the actual pressure. A handful of hornworms on a large plant is a hand-picking job: drop them into soapy water or, if the plant is otherwise healthy, just relocate them away from the garden. A heavy aphid colony calls for a strong jet of water first, since that alone knocks off a large share of them, followed by insecticidal soap sprayed directly on the colony if numbers rebound within a few days. For whiteflies, yellow sticky traps placed near the plant tops give you both a control method and an early warning system, since you’ll see numbers rise on the traps before the infestation is visible on leaves. Always spray in the early morning or evening, never in full sun, since soap and oil sprays can scorch leaves in heat and also hit foraging bees when they’re most active.
What goes wrong
The most common failure is reacting to the first insect you see with a broad-spectrum insecticide, whether synthetic or an all-purpose “organic” product. This looks like diligence but it isn’t, because it wipes out ladybugs, lacewings, and parasitic wasps along with the pest, and those predators are often already suppressing the problem before you noticed it. Treating too broadly, too early, usually costs you more control than it gains.
A second mistake is scouting only the top of the plant. Hornworms in particular blend in so well with stems that people miss them entirely until the droppings on lower leaves give them away, by which point real damage is already done. Get in the habit of checking mid and lower foliage, not just the newest growth at the top.
Overwatering or letting plants go heat-stressed also compounds pest pressure, since stressed plants are more attractive to sap-feeders like aphids and mites and less able to recover from chewing damage. If your plants are also splitting fruit or showing leaf curl unrelated to insects, that’s usually a watering or nutrient issue rather than a pest problem. Finally, people sometimes assume that because a plant was started correctly, following the guidance in planting tomatoes, it’s somehow immune to pests. Good planting practice reduces stress and makes plants more resilient, but it doesn’t prevent insects from finding them.
Doing it differently
Container-grown tomatoes are easier to scout because you can walk around the whole plant and even rotate the pot, but they dry out faster, and the resulting stress makes them more attractive to aphids and mites. Check container plants slightly more often for that reason, especially in hot stretches.
Greenhouse or high-tunnel tomatoes face a different pest mix. Whiteflies and spider mites thrive in the still, warm air, and without wind or rain to knock populations down naturally, they can build up faster than on outdoor plants. Sticky traps and good airflow, achieved through ventilation or fans, matter more here than they do outdoors.
Raised beds don’t change the pest picture much on their own, but the tighter spacing common in raised-bed layouts means one infested plant can spread to its neighbors faster, so treat the whole bed as a unit when scouting rather than checking one plant and assuming the rest are fine. As for variety, indeterminate types kept on trellises or cages tend to show pest damage sooner because their foliage is more accessible for close inspection, while sprawling determinate varieties can hide an infestation low in the canopy for longer. Whatever your setup, the fundamentals from how to grow tomatoes still apply underneath all of this: a healthy, appropriately watered plant handles pest pressure far better than a stressed one, regardless of container, bed, or variety.
Common questions
Why do my tomato leaves have holes but I can’t find any bugs?
Check at night or early morning with a flashlight, since many chewing pests, including hornworms and some caterpillars, feed mostly in low light and hide during the day. Also look on the undersides and along stems, not just on the leaf faces, and check the soil surface at the base of the plant for slugs if the damage is ragged and low on the plant.
Are ladybugs and their larvae going to hurt my tomatoes?
No, ladybugs and their larvae are predators, not pests, and they eat aphids in large numbers. Ladybug larvae look nothing like the adult beetle, more like small dark alligators with orange markings, and people sometimes mistake them for a pest and kill them by accident. Learn to recognize the larval stage before you treat anything on a leaf covered in aphids.
Should I spray neem oil or insecticidal soap on a schedule, just in case?
Routine preventive spraying isn’t generally recommended, because it exposes beneficial insects to repeated doses even when there’s no pest problem to justify it. Scout first and treat only when you actually find a pest at levels doing visible damage. If you do treat, spray in the early morning or evening to limit contact with foraging bees.
Can I still eat tomatoes that had fruitworm or hornworm damage?
Yes, as long as you cut away the damaged portion and the rest of the fruit looks and smells normal. Fruit with an entry hole near the stem is more likely to have secondary rot inside, so check carefully before deciding whether to salvage it or discard it.