It’s impossible to own a garden without encountering a few pests. Aphids, mealybugs, spider mites – these pests seem to be a mandatory addition to most gardens.
However, there’s one curious pest you may or may not have encountered that can leave quite a memorable first impression and a lot of severe damage in its wake.
We’re talking about the aptly-named common flea beetle.
These tiny frustrating garden pests tend to target specific plants, so not every garden will have them. Vegetable plants and garden crops are especially susceptible to these pests.
However, it’s important to know what they are and how to deal with them to avoid a lot of potential damage to your plants.
What Is A Flea Beetle And How to Control Them In The Garden
Flea beetles are tiny garden pests that have some unique traits.
Let’s take a closer look at ways to identify them, then delve into control methods.
Flea Beetles 101
Flea beetles belong to the Alticini tribe, which belongs to the Chrysomelidae (leaf beetle) family.
They generally measure between 1/16 and ⅛” inches long, although the spinach flea beetle (Disonycha xanthomelas) grows to ¼” inches long.
Depending on the species of flea beetles, they can be black, blue, bronze, brown, or metallic gray.
Some are solid, while others have stripes or spots.
However, one feature all types of flea beetles have in common is their long black hind legs which allow them to leap much like fleas.
This curious trait is how they’ve earned their nickname, and it’s easy to be surprised the first time one jumps away from you.
Other common species of flea beetles include:
- Crucifer flea beetle
- Tuber flea beetle
- Tobacco flea beetle
- Striped flea beetle
Most flea beetles have a specific preference for food, with many species targeting specific genera or species of flowering or crop plants.
A notable exception to this is the pale-striped flea beetle (Systena blanda), which is known to feed on a variety of crops as well as weeds.
However, some flea beetle species are actually beneficial, such as the genus Aphthona, which has been employed in the US as a biological control against the invasive leafy spurge (Euphorbia virgata).
Adult flea beetles can overwinter beneath leaf litter, wooded areas, garden debris, and other places of shelter.
Once temperatures reach 50º degrees Fahrenheit in the spring, adult beetles emerge and begin to lay their eggs.
Some species will only lay a single egg at a time, while others lay in clusters.
They’ll deposit the clusters of eggs in tiny holes in the ground or among roots or leaves, which take 7 to 14 days to hatch.
As soon as they emerge, the tiny white larvae will begin feeding on tender roots, such as those of seedlings, before entering their pupal stage.
Unlike many other small insect pests, little black bugs only reproduce one to two times per year.
Identifying Flea Beetle Damage
Flea beetle larvae will attack the roots of seedlings and tend to do extensive damage to plants started from seed in the garden than those started indoors and transplanted.
The amount of damage they do is usually very minor (unless there’s a population explosion), although the larvae of the potato flea beetle (Epitrix cucumeris) can result in notable crop damage.
Adults tend to be far more destructive. They have a unique pattern, chewing irregular holes in leaves, stems, and flowers. The holes in leaves are irregular and generally rounded, measuring up to ⅛” inches across.
It’s important to note that their damage in leafy greens can be misidentified as cabbage loopers. So it’s best to keep a lookout and properly differentiate them.
As they continue to feed, the entire leaves will begin to yellow, fade, or develop splotches, and the flea beetle holes will become bigger and more numerous.
If not treated, they can quickly defoliate entire plants, with seedlings being the most vulnerable.
Even worse, flea beetles have known disease vectors and can infect your plants as they chew.
Chemical Methods Of Controlling Flea Beetles
There are a number of active ingredients that work well against flea beetle infestation, including:
- Lambda cyhalothrin
- Insecticidal dust
Be sure to read the product label and follow instructions carefully, although chemical treatments should always be a last resort, as they can lead to superbugs if overused.
However, you can use repellant formulations if chemical control is not your cup of tea.
Organic Methods Of Controlling Flea Beetles
There is actually a wide range of organic control methods that combat flea beetles.
Three natural insecticides are neem oil, pyrethrin, and spinosad.
Beneficial nematodes, braconid wasps, ladybugs, and tachinid flies are all great allies in the garden and will actively hunt flea beetles.
You can also take advantage of intercropping companion plants that are strong-smelling, as it will make it more difficult for the flea beetles to find their target.
Marigolds, mint, and onions (including ornamentals) are just a few great options.
Alternatively, you can plant trap crops, such as radishes, prior to planting the rest of your garden.
As the flea beetles will attack the biggest, earliest crops first, you can lure them out and kill them before they can go after your actual garden.
Physical Methods Of Controlling Flea Beetles
Floating row covers are a popular method of keeping your vegetable crops safe from flea beetle attacks. This will provide a physical barrier to feeling. However, you must first ensure no eggs or flea beetle larvae are hiding in the soil.
However, you’ll need to remove the row covers in time for pollination.
You can also place sticky traps throughout your garden to eliminate these pests.
Moreover, keeping your vegetable garden free of weeds and debris is another good way to keep flea beetle populations down, as they’ll have fewer places to hide.
Limiting the food sources by removing weeds for flea beetles will also help control these pests.
In addition, planting trap crops can also effectively handle flea beetle. Trap crops will lure the flea beetles instead of the main crop.
Attracting beneficial insects, such as soft-winged flower beetles, lacewings, and field cricket can also help reduce the population, as they will feed on them.
Finally, you can till the garden in the fall, exposing any adults and often killing them.
However, it would help if you planted a cover crop or otherwise protected the soil afterward so it isn’t left bare for the winter.