Holes in tomatoes are most often caused by caterpillars boring into the fruit, though slugs, stink bugs, and even cold weather during flowering can also be responsible. The size, shape, and location of the hole tells you exactly which culprit you’re dealing with, and each one calls for a different response.
Tomato Fruitworm (Corn Earworm)
The tomato fruitworm is the most common cause of deep, round holes bored into tomato fruit. These caterpillars, the larvae of the moth Helicoverpa zea, chew their way into the tomato and feed inside for 10 to 14 days. A single larva can enter several fruits during its development before dropping to the ground to pupate. What you’ll find inside is a hollowed-out cavity filled with dark pellets of waste (called frass) and shed skins.
The damage doesn’t stop at the tunnel itself. Fruit with fruitworm holes often ripens prematurely and develops secondary fungal rot. You may also notice earwigs or sap beetles moving into the damaged fruit to feed on what the caterpillar left behind. If you cut open a tomato and find a clean tunnel packed with debris, fruitworm is your most likely answer.
Hornworms
Tomato hornworms are enormous green caterpillars, up to four inches long, that can strip entire leaves and small stems overnight. Their fruit damage looks different from fruitworm tunnels: rather than boring a neat hole, hornworms chew large, irregular pieces from the surface of green tomatoes. The fruit looks gouged rather than punctured.
The easiest way to confirm hornworms is to check the ground beneath your plants. Large black or dark green droppings, roughly the size of a peppercorn, are a telltale sign. The caterpillars themselves are well camouflaged against stems and leaves, so the droppings are often spotted first.
Slugs
Slugs chew shallow, irregular holes in tomatoes, often near the bottom of the fruit or wherever it touches the ground. They feed at night and hide during the day, so you rarely catch them in the act. Look for shiny slime trails on the fruit or nearby soil as confirmation. Slugs are most active in spring and summer, particularly in wet conditions or heavily mulched gardens.
The holes slugs leave are ragged and uneven, not clean tunnels. They may also chew irregular holes in leaves, sometimes defoliating plants entirely. If your tomatoes sit low to the ground and develop shallow, scooped-out damage overnight, slugs are the likely cause.
Stink Bugs
Stink bug damage doesn’t look like a typical “hole.” Instead, these insects pierce the tomato skin with needle-like mouthparts and suck out the contents of cells beneath the surface, creating what’s known as “cloudy spot.” On green fruit, the damage appears as whitish patches with a tiny black dot in the center where the mouthparts entered. On ripe fruit, those spots turn golden yellow. Individual spots range from about 1/16 to 1/2 inch across, and they can merge into large discolored patches.
If you peel back the skin over a cloudy spot, you’ll find a white, shiny, spongy mass of damaged tissue underneath. The fruit is still structurally intact, but the texture and flavor in those areas are ruined.
Catfacing and Zipper Scars
Not all holes in tomatoes come from pests. Catfacing produces deep indentations and cavities at the blossom end of the fruit, sometimes severe enough to look like something chewed through the tomato. The actual cause is a problem during flower formation that prevents the fruit from developing normally.
Cold nights are the primary trigger. Tomato flowers don’t develop or pollinate properly when nighttime temperatures drop below 52 to 54°F, even if daytime temperatures reach the 80s. Larger, rounder varieties are most susceptible. In the same garden, your beefsteaks and slicers may show heavy catfacing while cherry and grape tomatoes escape with little or no damage. Heavy pruning of indeterminate varieties can also increase the problem by reducing the plant’s natural growth hormones.
A related defect called zippering creates thin scars running from the stem end to the blossom end. Sometimes a small hole forms along the zipper scar on the side of the fruit. This results from abnormalities in early flower development rather than insect damage.
Are Damaged Tomatoes Safe to Eat?
Any hole that breaks the skin of a tomato creates a pathway for bacteria and other pathogens to enter the fruit. As a general rule, you should discard tomatoes when the skin is broken, especially if the area around the hole has softened or changed color. Softening and discoloration around a wound indicate that decay or microbial growth has already started.
If the damage is purely cosmetic, like minor catfacing or a shallow surface scar with no break in the skin, the tomato is fine to eat. But fruit with caterpillar tunnels, slug damage, or any hole that penetrates through the skin should be tossed. The risk of foodborne illness isn’t worth saving one tomato.
How to Prevent Holes in Your Tomatoes
For caterpillar pests like fruitworms and hornworms, timing is everything. A spray containing Bt (a naturally occurring soil bacterium that kills caterpillars) works best against newly hatched larvae before they bore into the fruit. Once a caterpillar is inside the tomato, no spray can reach it. Bt is approved for organic gardening and has a zero-day waiting period before harvest, meaning you can spray and pick the same day. Check your plants regularly and apply at the first sign of small caterpillars or fresh eggs on leaves and fruit.
Handpicking is effective for hornworms because of their large size. Check plants in the early morning or evening when the caterpillars are most active on the outer foliage. If you spot the characteristic large droppings, look carefully at the stems above, the hornworm is almost certainly there.
For slugs, reduce moisture around the base of plants. Avoid watering in the evening, remove debris where slugs hide during the day, and consider staking or caging plants to keep fruit off the ground. Copper tape around raised beds and shallow dishes of beer (which attract and drown slugs) are also effective deterrents.
To minimize catfacing, avoid planting tomatoes outside too early in the season. Wait until nighttime temperatures reliably stay above 55°F. Choosing smaller-fruited or plum-type varieties also reduces your risk, as does avoiding aggressive pruning on indeterminate plants.