If the leaves in your vegetable garden are suddenly full of tiny round holes and small dark beetles jump away when you brush the plants, you're most likely looking at flea beetles. Around your Roseland home, they tend to show up in spring, just as you're setting out young plants. They're small, but they can do real damage to seedlings. Below, we'll cover what flea beetles are, how to recognize their damage, which plants they prefer and what you can do to protect your garden. If you're finding insects you can't identify, our pest inspection services can help you sort it out.
What Flea Beetles Are
Flea beetles are a group of small leaf beetles. They get their name from their thick back legs, which let them spring away like fleas the moment they're disturbed. They aren't related to fleas, and they don't bite people or pets.
- Size. Very small, often about the size of a pinhead to a sesame seed.
- Color. Usually shiny black, bronze, metallic blue or green. Some have pale stripes.
- Behavior. They sit on the leaf surface and jump when you get close.
Adults spend the winter in leaf litter, weeds and plant debris near the garden. They become active as the weather warms in spring and move onto the first tender plants they find. Their larvae live in the soil and feed on roots, though the adults cause most of the damage you'll notice.
Flea beetles are most active on warm, sunny days. On cool or cloudy days they may hide lower on the plant or in the soil, so a garden that looked clean in the morning can be busy by afternoon. Some species have more than one generation a year, which means a second round of feeding can show up later in summer, often on fall crops like kale, radish and turnips.
Signs Of Flea Beetle Damage
- Shot holes. Many small, round holes or pits in the leaves, as if they were hit with tiny pellets.
- Damaged seedlings. Young plants that look stunted, wilted or chewed down soon after planting.
- Jumping insects. Tiny beetles that leap off the leaves when you touch or shake the plant.
- Brown, papery spots. Older feeding marks can dry out and turn brown around the edges.
Plants Flea Beetles Prefer
Different species prefer different plants, but two plant families are frequent targets in home gardens:
- Tomato family. Eggplant is a favorite, along with tomato, potato and pepper.
- Cabbage family. Radish, arugula, kale, cabbage, broccoli, turnip and mustard greens.
Some species also feed on corn, beans, beets, spinach and flowers. Some flea beetles can spread plant diseases as they feed, which is another reason to keep them in check on young plants. If you're also seeing yellow and black striped beetles on your squash or cucumbers, those are a different leaf beetle. Our guide on how to control cucumber beetles covers them.
Are Flea Beetles Harmful?
To people, pets and your home, no. They don't bite, sting, carry disease to people or come indoors to breed. The concern is for your plants.
Established plants can usually handle some feeding and keep growing. Seedlings are another story. A small plant has only a few leaves, and heavy feeding in its first weeks can stunt it or kill it outright. Leafy crops like arugula and kale can also become hard to sell or unappealing to eat when every leaf is full of holes.
How To Protect Your Garden
- Use floating row covers. Lightweight fabric over young plants keeps beetles off. Seal the edges with soil, and remove the cover from plants that need bees for pollination once they flower.
- Start with sturdier plants. Larger, healthy transplants handle feeding better than tiny seedlings.
- Time your planting. Planting a little later in spring can help plants avoid the first wave of hungry beetles.
- Clean up debris. Remove old plant material and weeds in the fall, since adults overwinter there.
- Try a trap crop. Some gardeners plant radishes nearby to draw beetles away from more valuable crops.
- Use sticky cards. Yellow sticky cards near plants can catch adults and show you when they're active.
When To Call A Professional
Most flea beetle problems are best handled with garden practices, and a local garden center or your county office of Rutgers Cooperative Extension can help with crop-specific advice. EcoFusion doesn't provide vegetable garden treatments. Where we help is when you aren't sure what you're dealing with, or when insects from the yard start finding their way into your home. Our NJ DEP-licensed technicians can inspect your property, identify the pests you're seeing and recommend a plan using Integrated Pest Management and EPA-registered, eco-safe products.
Flea beetles are small, but on young plants they can make a big difference. A little early protection goes a long way toward a healthy garden at your Roseland home.