Round Holes in Leaves: Bee, Beetle, Slug, or Caterpillar?

Perfectly circular holes or half-moon notches cut from leaf edges are almost always leafcutter bees, which are beneficial pollinators that do no lasting harm. Rounded but irregular holes in the middle of leaves point instead to slugs, caterpillars, or — if the holes are tiny and numerous — flea beetles.

Most likely causes

  • Leafcutter bees — smooth, perfectly round or half-moon cuts along leaf edges
  • Slugs — roundish but irregular holes with slime trails nearby
  • Flea beetles — dozens of tiny round 'shotholes' scattered across the leaf
  • Caterpillars — rounded holes that grow larger daily, with droppings below

Compare the possible causes

Possible cause Key signs When it happens How likely
Leafcutter bees Circles and half-moons about the size of a dime cut cleanly from the leaf edge, as if done with a hole punch Late spring through summer, appearing over a few weeks then stopping Very common
Slugs and snails Rounded but uneven holes in the middle of the leaf as well as the edges, with silvery dried slime on leaves or soil Damp nights spring through fall, worst after rain Very common
Flea beetles Many tiny round holes about 1/16 inch across peppering the leaf, giving it a shot-full-of-birdshot look Late spring and early summer, concentrated on young plants Common
Caterpillars Rounded holes that started small and enlarge day by day, often with dark specks of droppings on leaves below Spring through early fall, whenever butterflies and moths are laying eggs Common

Visual clues to check

  • Study the hole's edge: perfectly smooth and circular means leafcutter bee; ragged or wavy means something was chewing, not cutting
  • Note the location: cuts only along leaf edges point to leafcutter bees; holes through the leaf's middle point to slugs or caterpillars
  • Count the holes: one to a few dime-sized circles suggests bees; dozens of pinholes suggests flea beetles
  • Shine a flashlight at a low angle across the leaf to catch dried slime trails, the slug signature
  • Flip the leaf over and check for caterpillars, eggs, or dropping specks along the veins
  • Watch the damage over three days: bee cuts stay identical, while insect feeding holes visibly enlarge

The causes in detail

Leafcutter bees

A leafcutter bee snips out each precise disc in under a minute and carries it off to line her nest cavity — roses, redbuds, and lilacs are favorites. No other cause makes cuts this geometric and clean-edged. The bees are gentle solitary pollinators, the plant is not harmed beyond cosmetics, and there is nothing to treat; entomologists universally recommend leaving them alone.

Slugs and snails

Slug holes look round at a glance but wobble when you look closely, and they often punch through the middle of the leaf rather than the edge — something leafcutter bees never do. Slugs favor soft, low foliage like hostas, lettuce, and seedlings. The confirming evidence is the slime trail, which shines when you angle a flashlight across the leaf.

Flea beetles

If the round holes are numerous and tiny rather than one or two big ones, think flea beetles. These small dark beetles jump away when you touch the plant, which is the quickest field test. They target seedlings and young vegetables — eggplant, tomatoes, radishes, brassicas — and mature plants usually outgrow the damage.

Caterpillars

Young caterpillars chew small round windows in leaves, and the holes grow with the caterpillar. Check the undersides of damaged leaves for the culprit itself, for pale eggs, or for pepper-like droppings. Damage that expands daily is the giveaway — a leafcutter bee's circle never changes size after it's cut.

When to worry

  • Seedlings and transplants losing most of their leaf area to shotholes or slug feeding — small plants can't outgrow heavy damage
  • Holes spreading rapidly across a vegetable bed within a week, suggesting an active and growing insect population
  • Slime trails on ripening fruit or vegetables, since slugs move from leaves to produce
  • Damage plus curled, sticky, or yellowing leaves, which suggests a second pest is also at work

What to do now

  1. Identify before acting — if the holes are clean circles from the edge, it's leafcutter bees and the right response is to do nothing
  2. For slugs, set a board or overturned pot near the plants and collect the slugs sheltering under it each morning
  3. Protect seedlings from flea beetles with floating row cover until plants are 6–8 inches tall
  4. Handpick caterpillars in the evening and check leaf undersides for egg clusters you can rub off
  5. Keep mulch pulled back a few inches from seedling stems to reduce daytime slug shelter
  6. If a prized shrub is being heavily damaged and you can't find the cause, bring photos and a sample leaf to your county extension office

What not to do

  • Don't spray insecticide at leafcutter bee damage — the bees are important pollinators, the plant isn't harmed, and the spray will hit other beneficials
  • Don't kill caterpillars before checking what they become; on parsley, dill, or milkweed they may be swallowtail or monarch larvae
  • Don't rely on salt for slugs — it damages soil and roots far more than it controls the pest
  • Don't tear off every damaged leaf; leaves with a few holes still feed the plant

Frequently asked questions

What makes perfect circles in leaves?

Leafcutter bees. The female cuts dime-sized discs and half-moons from leaf edges with surgical precision and uses them to wrap her nest cells. No chewing insect leaves edges that smooth. The damage is purely cosmetic, and the bees themselves are docile pollinators worth keeping around.

Should I get rid of leafcutter bees?

No. They don't damage plant health, they very rarely sting, and they pollinate flowers and vegetables. Their cutting season lasts only a few weeks. If the look bothers you on a prized rose, drape it loosely with fine netting during early summer instead of treating anything.

How do I tell slug holes from caterpillar holes?

Look for the evidence each one leaves behind. Slugs leave silvery slime trails on the leaf or nearby soil and feed mostly at night on lower foliage. Caterpillars leave dark pepper-like droppings and are usually findable on the leaf underside near the freshest hole.

Why are there hundreds of tiny holes in my seedlings' leaves?

That's the calling card of flea beetles — small dark beetles that jump when disturbed and chew 1/16-inch round pits and holes. They concentrate on young plants in late spring. Row cover over new transplants is the most reliable protection, and established plants generally outgrow the injury.

Related yard clues

Plant Damage Holes in Hosta Leaves: Slugs, Earwigs, Hail, or Deer? Holes in hosta leaves are most often slug feeding — hostas are the slug's favorite plant in the American shade garden, and silvery slime trails confirm it. Earwigs chew similar ragged holes in hot dry spells, hail punches holes with bruised edges all on the same date, and deer skip the holes entirely and eat whole leaves down to the stalks. Read the guide → Plant Damage Skeletonized Leaves: What Eats Everything but the Veins? Leaves chewed down to a lacy network of veins are usually the work of Japanese beetles or sawfly larvae such as rose slugs and pear slugs. Japanese beetles feed in plain sight in daytime swarms during midsummer, while sawfly larvae hide on leaf undersides and 'window-pane' the leaf from below — and stippled, bleached leaves that aren't actually eaten point to lace bugs instead. Read the guide → Plant Damage Leaves Chewed From the Edges: How to Read the Bite Marks Leaves eaten inward from the edges are usually caterpillars, grasshoppers, or — if the edges show neat crescent-shaped notches — adult weevils feeding at night. When whole leaf sections or stems are missing, the cut itself is the clue: a clean angled snip means rabbits, while ragged torn edges mean deer. Read the guide → Plant Damage What Is Eating My Tomato Leaves at Night? Tomato leaves that disappear overnight are most often the work of tomato hornworms, cutworms, slugs, or flea beetles — and if whole branches are gone, rabbits or deer. The size of the bites, whether there are slime trails, and how low on the plant the damage sits will point you to the culprit, and a ten-minute flashlight check after dark usually confirms it. Read the guide →

Still not sure? Compare with these clues

Bugs & Eggs Green Caterpillars on Plants: Which One Is Eating Yours? The green caterpillar on your plants is most likely a cabbage worm if it's on broccoli or kale, a tomato hornworm if it's large and has a tail spike, or a sawfly larva if it's on roses. Which plant is being eaten narrows it down fast, and handpicking plus row covers handle most of them — no spraying required. Keep in mind that some green caterpillars grow up to be butterflies worth keeping around. Read the guide → Bugs & Eggs Tiny Yellow Eggs Under Leaves: Pest or Friend? Tiny yellow eggs on the underside of leaves usually belong to squash bugs, ladybugs, Colorado potato beetles, or whiteflies. Identify them before you do anything — ladybug eggs look almost identical to pest eggs, and crushing them destroys one of the best aphid killers in your garden. Read the guide → Plant Damage White Squiggly Lines on Leaves: Leafminers Explained Those winding white or pale tan trails are made by leafminers — tiny fly, moth, or sawfly larvae that hatch inside the leaf and eat a tunnel between its upper and lower surfaces. The damage looks dramatic but is almost always cosmetic on ornamentals; picking off mined leaves is usually all the control a home garden needs. Read the guide →