Holes in Leaves: A Chart to Match the Damage to the Pest

What Causes Holes in Plant Leaves

Most holes in garden leaves come from chewing pests, and the shape of the hole tells you which one. Many tiny round holes mean flea beetles. A lace of veins with the green tissue gone means Japanese beetles. Large irregular holes with a shiny slime trail mean slugs or snails. Holes that keep growing, with dark green pellets underneath, mean caterpillars. Smooth half circles cut from the edge are leafcutter bees, and round tan spots that drop out of peach or cherry leaves are a fungal disease called shot hole.

That short list covers most of what shows up in a home garden. The chart below adds the less common causes and the plants each one favors. Read the damage first and look for the pest second, because several of these feeders work at night and hide during the day.

Leaf Hole Identification Chart

What the damage looks like	Likely cause	Where it shows up	How to confirm
Many tiny holes, as if peppered by a shotgun	Flea beetles	Cabbage, broccoli, kale, eggplant, potatoes, spinach, beets, beans	Tiny dark beetles, 1/16 to 1/4 inch long, jump when disturbed
Tissue eaten between the veins, a lace-like skeleton left	Japanese beetles	Over 350 plant species	Metallic green beetles on upper leaf surfaces, late June into September
Large, irregular holes in leaves, stems, flowers or fruit	Slugs and snails	Plants in cool, damp spots; fruit touching the soil	Shiny trail of slime; feeding at night or on dark, cloudy days
Numerous small, irregular holes, ragged look, no slime	Earwigs	Dahlias, zinnias, marigolds, hostas, lettuce, strawberries, seedlings	Flat reddish-brown insects, 1/2 to 1 1/4 inches, in traps by morning
Small smooth holes that enlarge until only the midrib remains	Caterpillars such as imported cabbageworm	Cabbage, broccoli, cauliflower, collards, kale	Dark green fecal pellets on or beneath the plant
Crescent-shaped notches along the leaf margin	Black vine weevil adults	Yew, hemlock, rhododendrons	Night feeding that begins in late May to early June
Smooth semicircular cuts about 3/4 inch across, from the edge	Leafcutter bees	Rose, green ash, lilac, Virginia creeper	Clean cut with no chewing marks or droppings
Small round purple to tan spots that fall out	Shot hole disease	Peach, nectarine, apricot, cherry, almond	Spots seldom 1/4 inch across; no insects present

Tiny Holes in Leaves: Flea Beetles and Shot Holes

Tiny holes scattered across a leaf are called shot holes. The University of Wisconsin describes flea beetle feeding as many tiny holes that may or may not go all the way through, leaving leaves that look peppered by a shotgun. The adults are only 1/16 to 1/4 inch long and typically dark, and they spring away like fleas when you brush the plant.

Size of the plant decides how much this matters. Recently emerged seedlings are the most vulnerable and can be killed by a heavy infestation, while larger plants carry the pitting without much trouble. Floating row covers keep flea beetles off the crop, provided they go on just before the crop emerges or immediately after transplanting.

On stone fruit the same peppered look has a different cause. Shot hole disease, also called coryneum blight, is a fungus that produces small round purple to tan lesions on peach, nectarine, apricot, cherry and almond. The dead spots, seldom 1/4 inch across, cannot stretch as the leaf expands, so they tear out and leave a hole. Utah State University notes the fungus is active in cool, continuously moist conditions, which is why keeping irrigation water off branches and leaves is part of the standard management along with pruning out infected twigs.

Lacy, Skeletonized Leaves: Japanese Beetles

When the veins are intact and everything between them is gone, the feeder was a Japanese beetle. Adults are shiny metallic green, slightly less than 1/2 inch long, and they eat from the upper surface of the leaf. They are not picky, with more than 350 host species recorded, including fruits, vegetables and ornamentals.

In the Upper Midwest the adults emerge in late June or early July and can be found into September, so lacy leaves in April or May point to something else. They are most active on warm, sunny afternoons, which makes them easy to find. On small plants, knock or pick the beetles into a container of soapy water. Wisconsin’s extension service advises against pheromone lure traps because the lure draws in more beetles than the trap catches. The larvae are a separate problem: they feed on grass roots and cause pale, brownish patches of lawn that roll back like carpet. The full season plan is in how to get rid of Japanese beetles.

Large Ragged Holes: Slugs, Snails and Earwigs

Large, irregular holes with no particular shape, in leaves, stems, flowers or fruit, are slug and snail damage. The confirming sign is a shiny trail of mucus on or near the leaf. Slugs thrive in cool, damp conditions and do most of their feeding at night or on dark, cloudy days, then nearly disappear in dry spells. Vegetables and fruit in direct contact with the soil take the worst of it.

This is the first thing to check on shade plants. Coleus, for example, prefers part shade or dappled light and soil that never fully dries, which is also what slugs prefer. For holes in coleus leaves, look for slime in the morning and go out with a flashlight after dark before blaming an insect.

Earwigs leave a similar ragged look made of numerous small, irregular holes, with no slime trail. They are flat, reddish-brown to black, and 1/2 to 1 1/4 inches long. Like slugs they feed mostly at night and spend the day in dark, moist crevices. A rolled piece of corrugated cardboard or newspaper left near the damaged plant overnight will hold them by morning, when it can be shaken into a pail of soapy water.

For slugs, the cultural controls come first: clear debris and hiding places, water in the morning so the surface dries by evening, and lay a board on the soil as a trap, then collect and destroy the slugs that gather under it. A container of fresh, undiluted beer works as a trap too.

Holes That Grow and Leaves Stripped to the Midrib: Caterpillars

Caterpillar damage starts small and does not stay that way. The imported cabbageworm, the velvety green caterpillar found on cabbage, broccoli, cauliflower, collards and kale, begins with small, smooth feeding holes that enlarge until the whole leaf is consumed and only the midrib is left. A full-grown one is about 1 1/4 inches long with a single yellow stripe down its back, and it is the same green as the leaf it sits on.

The droppings are easier to spot than the caterpillar. Large amounts of dark green fecal pellets scattered on or under the plant mean a caterpillar is feeding directly above. Handpicking works on a few plants. Bacillus thuringiensis, sold as Bt, is a microbial insecticide that the University of Maryland rates as highly effective on younger caterpillars, and a floating row cover prevents the butterflies from laying eggs in the first place.

Circular Holes and Notched Edges: Leafcutter Bees and Weevils

Damage that starts at the leaf edge has two common sources, and they are easy to tell apart. Leafcutter bees make a smooth semicircular cut about 3/4 inch in diameter, as neat as a hole punch. They carry the pieces off to line their nests, favoring rose, green ash, lilac and Virginia creeper. Colorado State University calls the injury a minor curiosity and notes that insecticides do not prevent it. If a prized rose is being cut heavily, loose netting or cheesecloth over the plant while the bees are most active is the protection the university suggests. The bees are pollinators about the size of a honeybee, so leaving them alone is the usual choice.

Black vine weevil adults chew smaller crescent-shaped notches along the margin instead. They feed on more than 100 woody and herbaceous species, with yew, hemlock and rhododendrons the favorites. Adults emerge in late May to early June, feed at night, and cannot fly. Light to moderate notching has little effect on plant health. The larvae are legless grubs about 3/8 inch long that feed on roots, and they are much harder to control than the adults.

Confirm the Culprit Before You Treat

A pattern narrows the list, and a sighting settles it. Check the plant twice: once in a warm afternoon, when Japanese beetles are feeding in the open, and once an hour or two after dark with a flashlight, when slugs, earwigs and weevils come out. Turn leaves over, look along the midrib, and scan the soil surface for pellets or slime.

Size helps you know what to look for. Flea beetles top out at 1/4 inch and earwigs reach 1 1/4 inches, so one needs a close look at the leaf surface and the other is hard to miss in a cardboard trap.

If you find no pest, no droppings and no slime on two visits, consider causes that are not feeding at all. Shot hole disease is one, and physical injury such as hail is another. Old damage is a third: a Japanese beetle skeleton found in October was made weeks earlier, and new leaves that open clean tell you the feeder has gone. When slugs turn out to be the answer, slug and snail control: what actually works goes through the options in order.