If you ever come across plants with tiny, irregular holes or gashes in their leaves (almost like they’ve been shot with tons of small bullets), or see tiny, shiny beetles crawling across your vegetables and flowers, you’ve got a new pest to deal with: fleas.
These tiny insects can be black, brown, copper, blue or metallic gray and some species have spots or stripes. True to their name, they use their large hind legs to jump like fleas from plant to plant when disturbed. (They’re not the type of fleas that bite your dogs and cats.) And despite their size, fleas have voracious appetites that can weaken or outright kill small plants.
I used to struggle with flea beetles in my garden and once stopped growing tomatoes because I couldn’t control the outbreaks. They are most active in the spring and early summer, although they will hang around all summer if there is plenty of food and no predators to stop them. (I’ll get into that in a bit.)
But over time, I realized that they can be easily controlled with some simple (and non-toxic) methods. The key is to catch them early so your plants have a chance to recover. Here’s what I’ve learned and how you can stop them from devouring your garden.
Disclosure: If you shop from my article or make a purchase through one of my links, I may receive commissions on some of the products I recommend.
Cover your plants early
Success starts with prevention, and this method works best if you cover your garden bed from the start before flea beetles enter. Once you sow seeds or transplant seedlings, cover them with floating row cover (insect netting) or light frost cloth. Doing this prevents adult flea beetles from landing and laying eggs.
Combine this method with a sprinkling of diatomaceous earth over dry soil (more on that below) to ensure you don’t accidentally trap any emerging flea beetles under the cover. Once your plants have grown large enough to survive pest damage, you can remove the cover.
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Keep weeds under control
Flea beetles often start the year feeding on weeds in early spring before migrating into your vegetable garden. So, it’s worth it keep your property free of weeds in spring and early summer to discourage pests. A tidy yard leaves fewer breeding grounds for flea beetles and helps disrupt their life cycle.
Welcome predatory insects to your garden
Flea beetles have many natural predators, and you can make your yard a welcoming place for these types of beneficial insects by growing plants they prefer.
Little known beneficial insects such as lacewingsfriendly predatory waspsand tachinid flies are particularly attracted to plants with umbrella-like clusters of flowers, such as sedge, lantana, fennel, cilantro, and dill. I also grow perennial sea kale, lettuce, chives and thyme, which are giving me some of my first blooms in the garden (because you don’t want to wait until summer to get flowers).
An advantage of bringing these beneficial bugs into your garden is that they are also natural predators of others pests such as aphidsthrips and leaf hoppers. This means less work for you and a more balanced ecosystem in the long run.
Know their preferred host plants
Some species of flea beetles feed on certain types of host plants. You can manage infestations more effectively by grouping these plants together in a bed (to make them easier to cover) or by growing them far apart (to minimize damage to entire crops).
In my experience, flea beetles typically feed on plants in the Brassicaceae family, such as cabbage, kale, broccoli, turnips, and turnips.
Since none of these leafy greens rely on pollinators, they can be protected with floating row covers for the entire season (or until they are large enough to withstand pest damage). Just make sure you don’t already have flea beetles coming out of the soil under the row covers – a light sprinkling of diatomaceous earth in the soil will help take care of that (see my tips for this below).
Flea beetles also attack plants in the Solanaceae family, such as tomatoes, tomatoes, peppers, eggplants, and potatoes.
Although flea beetles typically target these two plant families, some species eat squash and melon leaves, and generalist species will readily feed on other crops if they are particularly hungry with no other options around.
One way to reduce your chances of pests on your preferred crops is to transplant them into the garden later in the season when flea beetle numbers are lower and your transplants larger. Which leads me to…
Plant earlier or later in the season
Flea beetles typically produce two overlapping generations per year, and understanding their life cycle can help you strategically time your plantings.
- Spring emergence (April to May): Overwintering adults emerge in early spring when daytime temperatures reach 50°F. This first wave of flea beetles begins to feed on whatever is available in their host range, including weeds and cotyledons of young seedlings.
- Egg production (May to July): Adults lay eggs in the soil near the base of host plants and continue to feed in this apical window of foliage.
- Second generation (July to September): A new generation of flea beetles emerges and feeds in the summer and fall before overwintering in yard debris.
Because they hop and feed so quickly, flea beetles can decimate seedlings in a matter of days. You can try to minimize their feeding window by starting seeds earlier or later in the season and/or transplanting larger plants that can avoid a little flea damage.
One such trap crop that works incredibly well along the edges of your garden bed is the nasturtium. Flea beetles love scalpels and they will overwhelm them by the hundreds!
They also love cruciferous vegetables, especially arugula and radishes, which grow quickly and are easily seeded between rows of tomatoes and other valuable crops.
No, your trap crops won’t look pretty after a while, and that’s the whole point: They’re sacrificial plants that “trap” fleas to save your other plants. Once a trap crop is infected, you can pull it up and throw it in the trash (not the compost pile) or let the fleas do so until their dwindling numbers are no longer a threat to the mature plants.
Apply diatomaceous earth to plants
Already dealing with a flea beetle infestation? Don’t wait too long to deal with it.
Diatomaceous earth (DE) is a natural, highly absorbent, chalk-like powder made from the fossilized skeletal remains of diatoms (microscopic aquatic organisms). Although it may seem soft to us humans, DE is actually quite sharp and abrasive as the skeletons are made of silicon.
When diatomaceous earth is used as an organic form of pest control, the silica particles scrape away the insects’ protective outer layers, absorb their body oils, and cause them to dehydrate and die. DE works on contact and any moisture will render it ineffective.
This means it’s important to apply diatomaceous earth directly to dry leaves where you see flea beetles and around the base of the plant where they drop to the ground (and where the adults emerge after pupation). You’ll need to reapply DE after a cool morning, rain, or irrigation, so it’s not the easiest method, but it’s the easiest way to see results.
I have found that the best way to apply DE is to “dust” the plants using a powder duster (which I have linked below). A few puffs on the leaves and a sprinkling on dry soil usually does the trick.
Use beneficial nematodes
Some beneficial insects operate above ground as they feed on adult flea beetles. But others are working below they grind and attack flea beetle larvae before they develop into destructive adults.
Beneficial nematodes are soil-dwelling predators that actively prey on beetle larvae while being harmless to plants. Specifically, the entomopathogenic nematode species Heterorhabditis bacteriophora and Steinermena carpocapsae target the larval stage of flea beetles and can be applied around the base of host plants as a soil drench.
You’ll want to make sure you apply beneficial nematodes when the grubs are actually in the soil (but not too old) so the nematodes have something to feed on. This means from late spring to early summer (May to July) after the eggs hatch.
If you’ve been dealing with flea beetles for years, I highly recommend using beneficial soil nematodes (which also work on other pests such as squash vine borers).
You may not need to use all of these methods to control flea beetles. But for me, the triple threat of covering my seedlings, planting more annuals and perennials to attract beneficial insects, and using beneficial nematodes completely took care of my beetle problem.
