South Carolina gardeners deal with a working list of ten pests that Clemson Cooperative Extension’s Home and Garden Information Center flags as the ones that actually damage home vegetable plots: tomato fruitworm, also known as the Corn earworm in South Carolina that gardeners battle in sweet corn, diamondback moth, cabbage looper, the Striped cucumber beetle in South Carolina that shows up alongside the Spotted cucumber beetle in South Carolina that gardeners find on squash and cucumber vines, the Squash vine borer in South Carolina that growers watch for in zucchini and summer squash, brown and green stink bugs, the Leaffooted bug in South Carolina that gardeners frequently report, tobacco and tomato hornworms, and silverleaf whitefly with potato aphid. Clemson puts pest pressure statewide from early May through October, with tomato fruitworm already flying by early May and stink bugs peaking July through early October. Start checking the undersides of leaves and the base of stems weekly the moment you set out transplants, not after you already see damage.
What South Carolina gardens actually deal with
Your zucchini leaves are ragged, your tomato has a soft brown hole near the stem, and you’re wondering which bug did it and whether it’s already too late. It’s probably one of a short list — cucumber beetles, fruitworm, hornworm, stink bug — and South Carolina’s long season means several of them cycle through your garden more than once before frost. The right move right now is to flip a few leaves over, look at the base of the stems, and check weekly from the day you transplant, before damage tells you what’s already happened.
Diamondback moth
The larva is a small, pale green caterpillar, tapered at both ends, that thrashes and drops off the leaf the moment you touch it. It feeds on the undersides of cabbage, collard and other brassica leaves, leaving thin, papery patches where it has eaten through one leaf surface but not the other. Clemson names it the most problematic brassica caterpillar in South Carolina home gardens, and it feeds early enough in the plant’s growth to stunt a head of cabbage before it forms. Row cover installed at transplant keeps the adult moth from laying eggs in the first place, which does more good than any spray applied after the damage shows.
Cabbage looper
This caterpillar is pale green with faint white stripes running its length, and it moves by arching its back into a loop because it lacks legs in its middle segments. Gardeners dealing with the Cabbage looper in South Carolina often find it feeding alongside the diamondback moth larva on their brassicas, and the two are often mistaken for one another.acks a full set of legs in the middle. It chews irregular holes clean through brassica leaves rather than skeletonizing them, and heavy feeding can hollow out a forming head of cabbage from the inside. Bacillus thuringiensis (Bt) sprays work well on young loopers, but the caterpillar has to actually eat the treated leaf, so coverage on the underside matters more than the amount you spray.
Tomato fruitworm (corn earworm)
Clemson lists this as the most damaging tomato pest in the state, and the larva explains why: it bores straight into the green fruit near the stem, leaving a small clean entry hole and a rotting cavity inside that you usually only find once you cut the tomato open. Larvae range from pale green to brown or pink with faint lengthwise stripes, and the adult is a plain tan moth that lays single eggs on leaves and flower clusters. Clemson’s data, centered on the Charleston area, puts this moth active from early May with four to five generations following through the season, meaning a garden that looks clean in June can still take fruit losses in September.
Striped cucumber beetle
This beetle is small, about a fifth of an inch, bright yellow with three bold black stripes running down its back and a black head. It chews holes in cucumber, squash and melon leaves and, more seriously, spreads bacterial wilt, which collapses vines seemingly overnight once the beetle has fed on an infected plant and moved on to a healthy one. Floating row cover over young cucurbits until they flower keeps the beetle off seedlings during the stage when a handful of bites can kill the whole plant.
Spotted cucumber beetle
Similar size and shape to its striped cousin but yellow-green with twelve black spots across the wing covers. It feeds on the same cucurbit family and also carries bacterial wilt, and the two beetles are often found on the same plant at once. Because both overwinter in garden debris, clearing old vines at the end of the season cuts down the population that emerges the following spring.
Squash vine borer
The adult is a day-flying moth that looks more like a wasp than a moth, with an orange and black body and clear hind wings, but the damage comes from its larva: a cream-white caterpillar with a brown head that tunnels inside squash and zucchini stems near the base. The first sign is usually a healthy-looking plant that wilts suddenly despite wet soil, and by then the borer is already inside. Slitting the stem lengthwise to remove the larva can save a plant caught early, but once a stem has fully collapsed, the vine is done.
Brown and green stink bugs
Both are shield-shaped, roughly a half to five-eighths of an inch long. One is mottled brown, the other solid green, and both release a sharp odor when handled or crushed. They pierce developing tomato and pepper fruit to feed, leaving pale, hard, cloudy spots under the skin that show up clearly once the fruit ripens. Clemson’s Charleston-area data puts stink bug activity peaking July through early October, which lines up with the stretch when tomatoes are sizing up on the vine.
Leaffooted bug
An elongated grayish-brown insect close to three-quarters of an inch long, named for the flattened, leaf-shaped expansions on its hind legs. It feeds the same way stink bugs do, puncturing fruit and leaving discolored, corky spots inside. Clemson notes it is most common from May through fall, and adults tend to cluster on ripening tomatoes in groups rather than showing up one at a time, which makes hand removal more effective here than against most other pests on this list.
Tobacco and tomato hornworms
These are the biggest caterpillars you will find in a Carolina garden, pale to bright green and up to four inches long, with diagonal white stripes down the sides and a curved horn at the tail end. The tomato hornworm’s stripes are V-shaped and its horn is black, while the tobacco hornworm’s stripes run straight and its horn is red. Both strip a tomato plant of foliage fast enough that a stem can go from full to bare in a couple of days, and dark green droppings on the leaves below are often the first clue you get before you spot the caterpillar itself.
Silverleaf whitefly and potato aphid
The whitefly is barely a sixteenth of an inch, pale and moth-like, and lifts off a plant in a small cloud when the leaves are disturbed. The aphid is soft-bodied, pear-shaped, and green or pink, clustering on stems and the undersides of leaves. Both feed by sucking sap and leave behind a sticky residue called honeydew, which then grows a black sooty mold on the leaf surface below. Neither bites through fruit the way stink bugs do, but heavy infestations weaken the whole plant and can spread plant viruses between them.
Telling damage apart
The shape of the damage points to the cause faster than spotting the insect itself does, and getting that right first saves a wasted spray. Chewed leaf edges and irregular holes almost always mean a chewing insect: a caterpillar like the cabbage looper, tomato hornworm or diamondback moth larva, or a beetle like the striped or spotted cucumber beetle. The damage looks ragged rather than uniform, and you will usually find dark frass on the leaves below.
Stippling, a fine speckled bleaching across the leaf surface, points to a sap-sucking insect rather than a chewer: aphids, whitefly or spider mites feeding from underneath. Turn the leaf over. A sticky film or small white insects lifting off in a cloud means whitefly. Clusters of small green or pink insects mean aphid, and either way the sticky residue on the leaf is honeydew, not disease.
Sudden wilting on a plant that has been watered on schedule points to squash vine borer or bacterial wilt spread by cucumber beetles, not a watering fault. Slit the base of the stem. Sawdust-like frass packed inside means borer. A stem that oozes a milky sap when cut, with wilting that starts in one leaf and spreads outward, fits bacterial wilt better.
Fruit damage needs its own read. A clean, small entry hole near the stem end with a hollowed, rotting interior is tomato fruitworm. A pale, cloudy, slightly sunken patch under otherwise intact skin, with no visible entry hole, is stink bug or leaffooted bug feeding, and it shows up more clearly once the fruit starts to ripen.
- Chewed edges or holes: caterpillar or beetle feeding, day or night depending on species
- Stippling or bleached patches: sap-sucking insect, check the underside of the leaf
- Sudden wilting despite watering: vine borer inside the stem, or bacterial wilt from cucumber beetle feeding
- Sticky leaves with black mold: whitefly or aphid honeydew, not a fungal disease on its own
- Cloudy or sunken spots on ripening fruit: stink bug or leaffooted bug puncture, not blossom end rot
When each one shows up
Pest arrival tracks the plant’s growth stage more reliably than the calendar, though Clemson’s Charleston-area monitoring gives a useful frame: pest pressure statewide runs early May through October, and several species inside that window keep their own rhythm worth watching for.
Diamondback moth and cabbage looper move in as soon as brassica transplants go into the ground, since both lay eggs on young leaves and the larvae need that tender growth to establish. Check the undersides of the first true leaves within a week or two of transplanting, well before you see any visible damage on top.
Tomato fruitworm follows the tomato crop itself. Clemson’s data, centered on the Charleston area, has the moth flying from early May, and because it runs four to five generations, a garden can see fresh egg-laying every few weeks straight through to fall. Start checking flower clusters and small green fruit as soon as the first blooms open, since that is where the moth lays.
Cucumber beetles arrive with the cucurbit seedlings and are most dangerous in the first two to three weeks after emergence, before the plant has enough leaf area to outgrow the feeding. Squash vine borer adults follow once vines are running, laying eggs at the base of the stem rather than on a leaf.
Stink bugs and leaffooted bugs build through the summer as fruit sets. Clemson puts stink bug activity peaking July through early October and leaffooted bug as most common from May through fall, both windows overlapping with the stretch when tomatoes and peppers are sizing up on the vine, which is exactly when their feeding does the most visible damage. Gardeners further inland or in the Upstate will see these same insects on a shifted schedule tied to their own local warm-up, so treat the Charleston-based window as a guide rather than a fixed date.
Gardeners in Tennessee deal with a similar midsummer stretch of stink bug and hornworm pressure, laid out in Garden Pests in Tennessee: What Shows Up, When, and How to Stop It, though cooler nights there shift some caterpillar generations later in the year.
What actually works
Prevention
Row cover, put in place at transplant and sealed at the edges, is the single most effective tool against diamondback moth, cabbage looper and the cucumber beetles, because it blocks egg-laying instead of trying to kill larvae after they have already found the plant. It has to come off once flowers open on cucurbits so pollinators can reach them, which is usually also the point where the plant has outgrown the worst beetle risk.
Crop rotation matters most for squash vine borer and the cucumber beetles, both of which overwinter in soil or old plant debris near where they fed the year before. Moving cucurbits to a different bed each season, and clearing vines out at the end of the year rather than tilling them under, cuts down the population waiting to emerge in spring.
Predatory insects, including lady beetles, lacewings and parasitic wasps, take a real bite out of aphid and whitefly numbers if you avoid broad-spectrum sprays that kill the predators along with the pest. Planting flowering herbs nearby gives them somewhere to stay once the first wave of aphids is cleaned up.
Intervention
Hand-picking works well against hornworms and leaffooted bugs specifically because both are large enough to see and slow enough to catch, and it costs nothing but a few minutes each morning. Bacillus thuringiensis (Bt) sprays kill caterpillars, including diamondback moth, cabbage looper and hornworms, without harming bees or predatory insects, but the caterpillar has to eat the treated leaf, so thorough coverage on new growth matters more than spray volume.
Stink bugs and leaffooted bugs are the hardest of the group to control with sprays, since the adults are mobile and quick to move off a treated plant. Removing them by hand into a bucket of soapy water in the cooler part of the morning, when they move slowly, does more good than most insecticide applications.
A few common home remedies do little against this list. Marigolds planted nearby do not measurably reduce cucumber beetle or hornworm numbers, and garlic or pepper sprays wash off within a day or two of watering or rain. Gardeners looking for a low-effort fix run into the same disappointment elsewhere, including in the far shorter season covered in Garden Pests in North Dakota: What Shows Up, When, and How to Stop It.
What control costs
Cost comparisons here are relative, since no source behind this page prices materials by name, but the order holds true across most home gardens.
| Method | Money cost | Time cost | How often repeated |
|---|---|---|---|
| Hand-picking (hornworms, leaffooted bugs) | None | A few minutes daily during peak season | Daily checks through the pest’s active window |
| Row cover and barriers | Low, reusable across seasons | One setup at transplant, removal at flowering | Replaced only if torn, otherwise lasts years |
| Biological controls (Bt, predatory insects) | Low to moderate | Applications need reapplying after rain | Every one to two weeks during an active infestation |
| Broad-spectrum insecticide sprays | Moderate, and recurring | Mixing and application each round | Repeated through the season, often weekly |
For a home garden, hand-picking and row cover are the cheapest options by a wide margin, since both avoid repeat purchases: the cover is a one-time buy that lasts several seasons if stored dry, and hand-picking costs nothing but attention. Biological sprays like Bt sit in the middle. They cost more than a bucket of soapy water but far less in time than daily hand removal, and they only need reapplying after rain washes the residue off the leaf.
Broad-spectrum insecticide sprays end up the most expensive path over a full season, not because any single application costs much, but because stink bugs, leaffooted bugs and successive fruitworm generations keep coming back, and each new wave calls for another round. They also strip out the lady beetles and parasitic wasps that would otherwise be doing some of the work for free, which tends to make the aphid and whitefly problem worse a few weeks later.
Local help
Clemson Cooperative Extension runs the state’s Home and Garden Information Center, which identifies pest specimens, tracks outbreak reports, and publishes the factsheets this page draws from. If you are not sure whether what is chewing your tomatoes is fruitworm or hornworm, or whether a wilting squash plant means borer or bacterial wilt, your county Clemson Extension office can look at a sample or a clear photo and tell you which. Find your local office and current factsheets through Clemson Extension, and remember that pest timing measured in the Charleston area will run a little differently in the Upstate or the Pee Dee.
Common questions
Why are my tomatoes rotting from the inside with no visible hole?
Look again at the stem end and the shoulder of the fruit for a small, almost pinhole-sized entry. That size and location is typical of tomato fruitworm, and the rot spreads out from that single entry point. A fruit with no entry hole at all but a cloudy, sunken patch under intact skin is more likely stink bug or leaffooted bug feeding rather than fruitworm.
Do ladybugs actually eat my aphids or is that just something people say?
They do, and both the adult and the larval stage feed on aphids, with the larva often eating more per day than the adult. The catch is that a broad-spectrum insecticide applied for another pest will kill the lady beetles along with whatever you were targeting, which is why aphid problems sometimes get worse a couple of weeks after a spray for something else entirely.
Is it too late to plant squash again if vine borer already got my first planting?
A second planting can still produce if it matures before the season’s insect pressure and weather turn against it, though this page does not carry a local frost or planting date for South Carolina, so check that timing against your county’s guidance before you decide. Clearing out the borer-infested vines completely, rather than leaving them in the bed, keeps that generation from building up right next to the new planting.
Can I just spray everything on a schedule to stay ahead of these pests?
Scheduled broad-spectrum spraying tends to backfire in a home garden, because it removes the predatory insects that would otherwise keep aphids and whitefly in check, and pests like stink bugs and leaffooted bugs are mobile enough to just move back in once the residue breaks down. Targeted treatment, timed to what you actually find on a plant, costs less over a season and does less damage to the predators doing part of the job for you.