What eats tomato plant leaves and how to spot the damage
Several insects, mites, and animals regularly chew holes in tomato leaves, and the damage pattern tells you which pest you're dealing with. Hornworms leave large, ragged holes and dark droppings on lower leaves. Aphids cause yellowing and sticky residue without obvious holes. Spider mites create a fine, pale stippling across the leaf surface. Japanese beetles skeletonize leaves—eating the tissue between veins and leaving a lacy appearance. Deer and rabbits bite leaf edges cleanly, while grasshoppers chew irregular holes throughout the plant.
The location of damage also matters. Hornworms and some caterpillars feed from the top down, so you'll see damage on upper leaves first. Aphids cluster on new growth and the undersides of leaves. Spider mites prefer the lower canopy where humidity is higher. Knowing what you're seeing helps you act before the pest population explodes.
Key Takeaways
- Hornworms are large green caterpillars that leave ragged holes and dark droppings, and a single worm can defoliate a branch in days.
- Aphids, spider mites, and whiteflies cluster on leaf undersides and cause yellowing, stippling, or sticky residue without obvious holes.
- Japanese beetles skeletonize leaves by eating tissue between the veins, leaving a lacy skeleton behind.
- Deer and rabbits bite leaf edges cleanly and can strip an entire plant overnight, while grasshoppers chew scattered irregular holes.
- Identifying the pest by damage pattern and location lets you choose the right control method before the infestation spreads.
Hornworms and other large caterpillars
Tomato hornworms are the most destructive caterpillar on tomatoes. They are fat, bright green worms up to 4 inches long with white stripes and a black horn on the rear end. A single hornworm can eat an entire branch of leaves in two or three days. Look for large, ragged holes in leaves and dark green or black droppings (called frass) on the leaves below where the worm is feeding.
Hornworms are hardest to spot because they blend into the plant. Check the undersides of leaves and the interior of the plant where light is dim. If you find one, you can hand-pick it—wear gloves because the horn looks threatening but is harmless. If you see a hornworm covered in small white cocoons, leave it alone; parasitic wasps have already laid eggs in it, and those wasps will kill many more hornworms.
Other caterpillars like armyworms and cutworms also chew tomato leaves, though they cause less damage than hornworms. Armyworms are brown or green and feed in groups, so damage appears in patches. Cutworms are usually active at night and may cut seedlings off at soil level rather than eating leaves higher up.
Aphids, spider mites, and whiteflies
Aphids are tiny soft-bodied insects, usually green or black, that cluster on new growth and leaf undersides. They don't chew holes; instead, they pierce the leaf and suck out sap, causing yellowing, curling, and stunted growth. A sticky, clear liquid called honeydew coats the leaves below an aphid colony. Ants often farm aphids for this honeydew, so if you see ants crawling up your tomato stem, look for aphids above them.
Spider mites are not insects but tiny arachnids that spin fine webbing on leaves and feed on the underside. Infested leaves develop a pale, stippled appearance—thousands of tiny dots where the mites have sucked out chlorophyll. The webbing is often the first sign you notice. Spider mites thrive in hot, dry conditions and can go from unnoticeable to severe in two weeks.
Whiteflies are small white insects that fly up in a cloud when you brush the plant. Like aphids, they pierce leaves and suck sap, causing yellowing and sticky honeydew. They cluster on leaf undersides and reproduce quickly in warm weather. All three pests weaken the plant and can spread viruses, so controlling them early matters.
Japanese beetles and grasshoppers
Japanese beetles are metallic green and copper insects about half an inch long. They eat the tissue between leaf veins, leaving behind a lacy skeleton of veins—this pattern is called skeletonization and is unmistakable. Japanese beetles feed during the day and are straightforward to spot. They are most active in mid-summer and usually feed on the upper leaves of the plant.
Hand-picking Japanese beetles into a cup of soapy water works well if the infestation is small. They are slow fliers and straightforward to catch in the morning when they are sluggish. If you have many plants, the damage is usually not severe enough to kill the plant, though it looks alarming. Japanese beetles also feed on many other plants, so they may move on after a week or two.
Grasshoppers chew irregular holes throughout the leaf, and damage is scattered across the plant rather than concentrated in one area. They are active during the day and visible, though they jump away quickly when disturbed. Grasshopper damage is usually minor unless there is a population outbreak in your area. Young grasshoppers (nymphs) are smaller and wingless but cause the same damage as adults.
Deer, rabbits, and other animals
Deer and rabbits bite leaf edges cleanly and can strip an entire plant in one night. Deer damage appears on the upper leaves they can reach while standing on hind legs, while rabbits eat lower foliage. Both leave a clean, sharp edge where they bit, unlike the ragged holes left by insects. If you see hoof prints or rabbit droppings near the plant, animal damage is the cause.
Deer are most active at dawn and dusk. A single deer can destroy several tomato plants in one feeding. Rabbits are smaller and may only eat seedlings or young plants, but they can be just as destructive in a vegetable garden. Fencing is the most reliable control—a 6-foot fence for deer or a 2-foot fence for rabbits, buried 6 inches into the ground to prevent burrowing underneath.
Groundhogs, squirrels, and birds occasionally eat tomato leaves or fruit, but they cause less damage than deer or rabbits. Groundhogs are most active in early morning and may eat entire seedlings. Squirrels usually target fruit rather than leaves. Birds peck at ripe fruit but rarely eat leaves.
How to tell the difference at a glance
| Pest or Animal | Damage Pattern | Where to Look | Other Signs |
|---|---|---|---|
| Hornworm | Large, ragged holes | Upper leaves and interior of plant | Dark green droppings on leaves below |
| Aphids | Yellowing, no holes | Leaf undersides and new growth | Sticky honeydew, ants on stem |
| Spider mites | Pale stippling | Leaf undersides, lower canopy | Fine webbing on leaves |
| Japanese beetle | Skeletonized (veins only) | Upper leaves | Metallic green insect visible |
| Grasshopper | Irregular holes scattered | Throughout plant | Insect visible during day |
| Deer or rabbit | Clean-bitten edges | Upper leaves (deer) or lower (rabbit) | Hoof prints or droppings nearby |
When to treat and when to leave it alone
Light damage—a few holes or yellowed leaves on a healthy plant—usually does not need treatment. Tomato plants are vigorous and can tolerate losing 20 to 30 percent of their leaves without a drop in fruit production. If the plant is still growing new leaves faster than pests are eating them, the plant will recover.
Treat when damage is spreading fast, when you see multiple pests, or when the plant is young and small. A seedling with half its leaves eaten will struggle to grow. A mature plant losing a few leaves to hornworms can afford it. Also treat if you see signs of disease—yellowing leaves combined with pest damage means the plant is already stressed and needs help.
Hand-picking works for hornworms, Japanese beetles, and grasshoppers. For aphids and spider mites, a strong spray of water from the hose knocks many off the plant. Neem oil or insecticidal soap work on soft-bodied insects like aphids and whiteflies but are less effective on thick-skinned pests like beetles. Always spray in early morning or late evening to avoid harming beneficial insects and to prevent leaf burn.
Frequently Asked Questions
Can I use the same treatment for all leaf-eating pests?
No. Soft-bodied insects like aphids and whiteflies respond to insecticidal soap or neem oil, but hard-bodied insects like Japanese beetles do not. Hand-picking works for large, visible pests like hornworms and beetles but is impractical for tiny aphids. Water spray works for spider mites but not for beetles. Identify the pest first, then choose the right method.
Is it safe to eat tomatoes if the plant has been sprayed?
Yes, if you follow label directions. Neem oil and insecticidal soap break down quickly and are safe for edible plants when used as directed. Always stop spraying at least the number of days listed on the label before harvest—usually 7 to 14 days. Wash fruit before eating regardless of treatment.
Why do some leaves turn yellow without visible holes?
Yellowing without holes usually means aphids, spider mites, or whiteflies are feeding on the underside and sucking sap. Check the underside of yellow leaves for tiny insects or webbing. Nutrient deficiency and disease can also cause yellowing, but those usually affect the whole plant, not just one area.
Will netting protect my tomato plants from insects and animals?
Netting works for birds and some insects but not for all pests. Fine mesh netting stops Japanese beetles and some caterpillars but is expensive and difficult to manage as the plant grows. Netting does not stop aphids or spider mites, which are too small. For deer and rabbits, fencing is more practical than netting.
How do I know if the damage is from disease instead of pests?
Pest damage is usually localized—holes, stippling, or eaten edges in one area. Disease damage is often symmetrical and affects the whole leaf or plant. Fungal diseases cause spots with rings or halos. Viral diseases cause mottling or distortion. If you see the pest itself or its droppings, it is pest damage. If you see no insect and the damage is spreading to many leaves at once, suspect disease.