Flea Beetles: How to Stop Shothole Damage on Seedlings and Vegetables

By the Garden Voila editorial team · Updated October 30, 2026 · How we verify

Flea beetles are tiny, shiny black, bronze, blue or striped beetles, about 1/16 to 1/8 inch long, that jump like fleas when disturbed and chew many small round holes in leaves, giving them a “shothole” look. They are most damaging to seedlings and young transplants of brassicas (radish, arugula, kale, cabbage, broccoli), eggplant, potatoes, tomatoes and peppers in spring. Protect young plants with row cover from the day you sow or transplant, start with sturdy transplants, keep plants growing vigorously with water and fertile soil, use yellow sticky traps or a trap crop such as Chinese giant mustard or radish, and spray kaolin clay or a product labeled for flea beetles only when seedlings are under heavy attack. Established plants tolerate a good deal of feeding.

Flea beetle field notes

What are flea beetles?

Flea beetles are leaf beetles in the tribe Alticini, a huge group with thousands of species worldwide. The Wikipedia article on flea beetles explains that their name comes from the enlarged hind legs that let them leap away when disturbed. Different species specialize on different plant families: crucifer flea beetles attack brassicas, potato and eggplant flea beetles attack nightshades, and corn flea beetles feed on corn and can spread Stewart’s wilt. The Colorado State University Extension fact sheet on flea beetles notes that damage is most serious on seedlings and that established plants usually outgrow it.

How do you recognize flea beetle damage?

• Many small, round holes about 1/16 to 1/8 inch across, scattered over leaves, giving a shothole or sieve-like appearance.
• Pits where beetles have eaten partway through the leaf; these turn brown and may later fall out as holes.
• Stunted seedlings and wilted or dead cotyledons on newly emerged radish, arugula and brassica seedlings.
• Tiny dark beetles that jump when you approach or touch the plant.
• Tunnels or pimples on potato tubers caused by larvae of the tuber flea beetle in some regions.

Shothole damage can also come from fungal and bacterial leaf spots. Look for the jumping beetles to confirm. The pest identifier and the plant problem identifier can help you distinguish them.

What is the flea beetle life cycle?

Adult flea beetles overwinter in leaf litter, hedgerows, woodland edges and plant debris near gardens. They become active in early spring when temperatures reach the 50s°F and immediately seek out emerging seedlings and newly set transplants. Adults feed and lay eggs in the soil near host plants; the larvae feed on roots for a few weeks, pupate in the soil, and a new generation of adults emerges in mid to late summer. Many species have one or two generations a year. The heavy spring feeding by overwintered adults is the most damaging stage for gardeners.

Which flea beetles attack which crops?

How do you prevent flea beetles?

1. Cover seedlings and transplants with row cover or fine insect netting immediately at sowing or planting, sealing the edges with soil or pins. For brassicas, keep covers on as long as needed; for eggplant, remove at flowering or hand-pollinate. Use the row cover fabric calculator to size it.
2. Rotate crops so brassicas and nightshades do not follow themselves, and cover new plantings in fields where beetles overwintered.
3. Use bigger, healthier transplants. Robust transplants tolerate feeding far better than tiny seedlings; time indoor sowing with the seed starting calculator.
4. Delay planting slightly for very susceptible crops, or plant very early before beetles are active, depending on your region.
5. Keep plants growing quickly with adequate water and fertility, so they outgrow feeding.
6. Clean up crop debris and weeds such as wild mustard and nightshades that host beetles.

How do you get rid of flea beetles?

• Yellow and white sticky traps placed just above seedlings catch many adults; replace them as they fill.
• Trap crops: crucifer flea beetles strongly prefer Chinese giant mustard, Southern Giant Curled mustard and radish. Plant a border of these a week or two before your main brassicas, and the beetles concentrate there.
• Kaolin clay sprayed on leaves creates a fine white film that deters feeding; reapply after rain and on new growth.
• Vacuuming with a handheld vacuum catches beetles that hop up from disturbed plants.
• Diatomaceous earth dusted on dry leaves may deter some feeding but loses effect when wet and can harm beneficial insects.
• Insecticides labeled for flea beetles, such as spinosad or pyrethrin products, can protect seedlings during heavy pressure. Apply in the evening and avoid flowering plants.
• Beneficial nematodes applied to moist soil can attack larvae and reduce the next generation.

How much flea beetle damage is too much?

The UMass Extension guide to flea beetle biology explains that crucifer flea beetles overwinter as adults and attack seedlings as soon as they emerge, which is why early protection matters most.

Seedlings with only a few true leaves can be killed by heavy feeding, so they need protection. Once plants have five or six true leaves and are growing vigorously, they usually tolerate significant leaf holes with little effect on yield. Commercial guidelines for brassicas often suggest action when seedlings lose more than about 10 to 20 percent of their leaf area. For leafy crops like arugula and bok choy, where the leaves are the harvest, even cosmetic damage matters, so covers are the best approach. For tomatoes and potatoes, moderate damage on established plants is rarely worth spraying.

Flea beetles on eggplant

Eggplant is one of the most attractive crops to flea beetles and one of the least tolerant when young. Set out large, healthy transplants after the soil warms, cover them immediately with row cover and keep them covered until they are large and flowering. If covers come off early, check daily and use kaolin clay or a labeled product on young plants under heavy attack. Mature eggplants with many leaves can handle more damage. For other nightshade pests, see Colorado potato beetles and tomato hornworms.

Flea beetles on radishes, arugula and greens

Quick crops such as radishes and arugula are often riddled with holes in spring. Sow them under fine netting from day one, or grow them in early spring or fall, when beetle activity is lower. Radish roots are rarely affected even when leaves are holed, so radishes can still be harvested, but arugula and mustard greens grown for salads need full protection. See easiest vegetables for beginners for timing these crops.

Do companion plants reduce flea beetles?

Some studies have found that intercropping brassicas with other plants, such as clover living mulch, tomatoes or tall flowering plants, reduces flea beetle numbers on the brassicas, likely by making them harder for beetles to find. Results vary, and the effect is usually smaller than that of row covers or trap crops. Mustard and radish trap crops have the best evidence. See companion planting: what works for an evidence-based look at other combinations.

You can find guides to related pests and diseases in our plant pests and diseases hub.

Flea beetle FAQ

When are flea beetles worst?

In most temperate regions, flea beetle damage peaks in spring, typically from April to early June, when overwintered adults emerge hungry just as gardeners sow radishes, arugula and brassicas and set out eggplant and tomato transplants. Warm, dry, sunny weather makes them more active, while cool, wet weather slows them. A second, smaller wave of new adults appears in mid to late summer and can damage fall brassica plantings. Plan covers for both spring and late-summer sowings, and use the frost date tool to time plantings so seedlings are as strong as possible when beetles become active.

Do flea beetles spread plant diseases?

Some do. The corn flea beetle transmits the bacterium that causes Stewart’s wilt, which can stunt or kill susceptible sweet corn varieties, especially after mild winters when more beetles survive. Choosing resistant sweet corn varieties is the main defense. Flea beetle feeding wounds on potato and tomato leaves can also provide entry points for fungal diseases such as early blight. On brassicas, feeding damage mainly reduces growth rather than spreading disease.

Do flea beetles damage potato tubers?

Most potato flea beetle damage is to leaves and is cosmetic once plants are established. In parts of the Pacific Northwest and western Canada, however, the tuber flea beetle’s larvae tunnel into tubers, leaving pimples, slivers and short tunnels that reduce quality. If you garden in those areas and see such damage, rotate potatoes far from previous plantings, keep plants vigorous, and check with your local extension office for regional recommendations. Elsewhere, focus on protecting young potato plants from heavy leaf feeding.

How do you keep row covers working against flea beetles?

• Install immediately after sowing or transplanting, before beetles find the crop.
• Seal edges completely with soil, sandbags or pins; flea beetles find small gaps quickly.
• Rotate the bed so beetles are not emerging from the soil inside the cover.
• Use fine mesh: lightweight row cover or insect netting with small openings.
• Support covers on hoops so plants have room to grow and leaves do not press against the fabric, where beetles can feed through it.

With early covers, a trap crop and vigorous transplants, flea beetles become a minor nuisance rather than a reason to give up on spring arugula, radishes and eggplant.

If damage still appears under covers, lift a corner on a warm afternoon and check for beetles that may have emerged from the soil inside, then move the planting to a fresh bed next time.

Healthy, fast-growing plants are the best defense of all.

Keep an eye on new sowings for the first three weeks, when seedlings are most fragile, and act quickly at the first sign of shotholes.

Sources: Colorado State University Extension, Flea Beetles; UMass Extension, Flea Beetle Biology; Wikipedia, Flea beetle.

What university research says about timing and thresholds

The University of Minnesota Extension describes adult flea beetles as very small, roughly 1/16 to 1/8 inch (2 to 3 mm) long, in black, bronze, bluish, brown or metallic grey, with large back legs that make them jump when disturbed. The spinach flea beetle is larger at about 1/4 inch. Adults overwinter in leaf litter, hedgerows, windbreaks and wooded edges, then become active in early spring, which is why damage is worst on spring seedlings.

Seedlings suffer, bigger plants cope

Minnesota Extension notes that seedlings tolerate feeding far less well than transplants. Heavy feeding can wilt or stunt them. Its treatment guide for seedlings is more than five beetles per plant, or 10 to 30 percent of leaves lost. By summer, crops are usually at the four- or five-leaf stage and can tolerate feeding, and adult numbers decline, so treatment is generally unnecessary. Plants also grow faster in warm weather, so a slightly later sowing can outgrow the damage.

Row covers and a radish trap crop

Screening or floating row covers keep beetles off young plants. Remove them before flowering so pollinators can reach the crop, and note that covers make weeding harder and beetles can slip in when the edge is lifted. Eggplant needs hoops because the cover cannot lie directly on it. For home gardens, the same source suggests planting radish ahead of the main crop as a trap, then treating the beetles once they are feeding on it. In farm trials in Washington, Pacific Gold mustard and pac choi worked best, and mixes of three brassicas beat one or two.

Sanitation and natural enemies

Remove crop debris after harvest to take away overwintering sites. A native braconid wasp, Microctonus vittatae, parasitizes adults, and generalist predators such as lacewing larvae feed on them, though the wasp is uncommon and is not sold. Kaolin clay gives mixed results and has to be reapplied after rain. If you do spray, the products listed for gardens include pyrethrins and spinosad; confirm the crop is on the label first.

Reviewed October 2026. Sources: University of Minnesota Extension: Flea beetles