A flea beetle is not a flea. Let’s get that out of the way right at the beginning! In fact, fleas and flea beetles have almost nothing in common, although they’re often confused with fleas by those less familiar with them. This is not the pest that bites your dogs and cats (and sometimes you).
But if it’s not a flea, what exactly is a flea beetle? How can you identify this surprisingly-common United States pest, and where are you likely to find it? Can you catch them before they jump away? Most importantly, how do you kill them before they can devour your prized vegetable plants?
Today, I’m going to teach you all about this agricultural pest, tell you how to wipe them out, and hopefully answer any and all questions you might have about flea beetles. There’s a huge amount of data to cover, so let’s dive in!
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Flea Beetle Overview
|Common Name(s)||Flea beetle, Crucifer flea beetle, Horseradish flea beetle, Striped flea beetle, Western black flea beetle, Eggplant flea beetle, Potato flea beetle, Tobacco flea beetle, Tuber flea beetle, Western potato flea beetle, Palestriped flea beetle, and other related common names|
|Scientific Name(s)||Phyllotreta cruciferae, Phyllotreta armoraciae, Phyllotreta striolata, Phyllotreta pusilla, Epitrix fuscula, Epitrix cucumeris, Epitrix hirtipennis, Epitrix tuberis, Epitrix subcrinita, Systena blanda, and other related species|
|Origin||North America, various regions|
|Plants Affected||Broccoli, horseradish, cabbage, radish, kale, turnip, collards, cress, other cruciferous plants, eggplant, potato, tomato, pepper, other members of the Solanaceae family, cotton, grape, pea, peanut, corn, oat, strawberry, pumpkin, and pears.|
|Common Remedies||Spinosad and pyrethrin sprays, beneficial parasitic insects, yellow sticky traps, floating row covers, diatomaceous earth, kaolin clay, neem oil, azadirachtin sprays.|
Types of Flea Beetles
There is a very wide diversity of beetles that are considered to be flea beetles. In scientific taxonomy, these beetles are all part of the tribe Alticini, which is part of the subfamily Galerucinae of the beetle family Chrysomelidae. While I’m going to touch on some of the Alticini tribe of flea beetles, I’m going to focus primarily on those which impact agricultural crops, especially food crops.
Before I start, I did want to mention that there are a few species of flea beetles which are considered beneficial, as they tend to consume weeds rather than food crops. However, their beneficial use is incredibly limited. With that, let’s get into some of the pest varieties!
Phyllotreta cruciferae, ‘Crucifer flea beetle’
Like both cabbage worms and cabbage loopers, the Crucifer flea beetle tends to be attracted to cruciferous plants of the family Brassicaceae. This small black beetle is local to the northern United States.
Phyllotreta armoraciae, ‘Horseradish flea beetle’
This black beetle has a wide and straight light brown stripe on either side of its body. As its name would imply, it prefers horseradish, although it does consume other plants. It is localized in the northern United States, generally east of the Rocky Mountains.
Phyllotreta striolata, ‘Striped flea beetle’
Like the Crucifer flea beetle, the striped flea beetle prefers Brassicaceae plants. This shiny beetle is black with crescent-shaped off-white stripes along its sides. It lives in both the eastern and Pacific regions of the United States.
Phyllotreta pusilla, ‘Western black flea beetle’
These small beetles are a shiny black color, and tend to live in the western United States. They prefer Brassicaceae plants.
Epitrix fuscula, ‘Eggplant flea beetle’
This textured black beetle is strange in appearance, as it looks hairy. Most commonly reported in the eastern United States, it is a solanaceous feeder, preferring eggplants.
Epitrix cucumeris, ‘Potato flea beetle’
The potato flea beetle is a very tiny beetle, shiny black in coloration. It prefers Solanaceae plants such as potatoes and tomatoes, and is generally found east of the Rocky Mountains in the United States.
Epitrix hirtipennis, ‘Tobacco flea beetle’
Tobacco flea beetles are brown with a large, darker spot on either side of their bodies. These are also solanaceous feeders, and have a wide ranged diet. They are common in warmer regions in the United States.
Epitrix tuberis, ‘Tuber flea beetle’
A major problem in the Pacific Northwest, the tuber flea beetle tends to prefer Solanaceae plants, but is drawn mostly to the tuberous roots. They are a dingy, almost matte black color.
Epitrix subcrinita, ‘Western potato flea beetle’
This brown flea beetle is common throughout the western United States. It, like other epitrix species beetles, prefers the Solanaceae plants as its food.
Systena blanda, ‘Palestriped flea beetle’
Primarily a pest in warmer parts of the United States, the palestriped flea beetle has an incredibly wide diversity of host plants. This makes it one of the most dangerous flea beetles, especially in agricultural areas such as California where it’s very common. Visually it looks quite similar to the horseradish flea beetle, a black beetle with off-white crescent-shaped stripes along its sides.
Life Cycle Of Flea Beetles
In the winter, flea beetles overwinter in their adult form. They often hide under leaves or dirt clods, or in protected areas. Once warmer weather comes in the spring, they begin to emerge over the space of a couple weeks.
The adults will feed on plants for several weeks before the females begin to lay eggs. Their eggs are typically laid in cracks in the soil around the base of their food plants. Once the larvae hatch, they typically feed on the slender root hairs or on plant matter in the soil. With the exception of the tuber flea beetle larvae, which are a risk factor to root crops, most of the larvae are not particularly harmful to plants.
After several more weeks, the larvae will pupate under the soil’s surface. Once the pupal stage has concluded, they emerge from the soil as adult flea beetles and begin the flea beetle life cycle again. Most types of flea beetles will produce at least two generations in a year, and in warmer climates, three or more generations are possible.
Common Habitats For Flea Beetles
While flea beetles live near their host plants of preference, they also require some form of shelter from birds and other predators. Generally, this protection comes in the form of something that they can hide beneath. In gardens, this can be leaf litter or beneath dirt clods and rocks.
Flea beetles are widespread across the United States, although the species varies depending on the location.
It can be easy to identify an area where flea beetles are widespread, as they are often known to cause extensive damage to the leaves of their favorite plants. The damage can look like mottled yellowing and browning over most of the surface of the leaf. In more drastic situations, entire leaves can be skeletonized, leaving only leaf veins intact.
What Do Flea Beetles Eat?
While I touched briefly on this while describing the beetles themselves, flea beetles generally fall into one of two categories: cruciferous, or solanaceous.
The cruciferous varieties tend to be part of the Phyllotreta species. These beetles vary in their diets by the specific species, but tend towards broccoli, horseradish, cabbage, radish, kale, turnip, collards, and cress. At least one (the Western black flea beetle) is also known to consume beet, lettuce, and potato.
The solanaceous varieties are generally Epitrix species beetles. These tend to eat eggplant, potato, tomato, pepper, and other members of the Solanaceae family.
The palestriped flea beetle has an incredibly wide diet. This Systena species beetle will consume most Solanaceae family plants (tomato, potato, eggplant, pepper, etc), along with cotton, grape, pea, peanut, corn, oat, strawberry, pumpkin, and pears. This makes them particularly dangerous amongst agricultural pests.
How To Get Rid Of Flea Beetles
While there are a diverse number of species considered flea beetles, thankfully all of them are vulnerable to the same control methods. Let’s look at the different measures you can take to get rid of these plant devourers.
Organic Flea Beetle Control
Spinosad sprays such as Monterey Garden Insect Spray are effective against flea beetles. These work to poison the beetles after the spinosad is consumed on the plant matter, so it takes a day or two before the beetles die. A few spaced-out applications of this will eradicate the majority of flea beetles in your garden, leaving only those in pupal form beneath the soil’s surface.
Pyrethrin sprays work even faster to eliminate the flea beetles. A good pure pyrethrin spray that I like to use is PyGanic, which works on contact. If you have issues with other beetle types such as Japanese beetles at the same time as your flea beetle woes, you might consider a pyrethrin spray that combines both the power of pyrethrin and potassium salts of fatty acids, such as Safer Brand Home & Garden Spray. The pyrethrins will kill smaller beetles, but on the thicker-shelled beetles, the potassium salts will help eat into the beetle’s shell and allow the pyrethrins to do their job.
Environmental Flea Beetle Control
One good option to combat the flea beetle is to plant trap crops. In essence, these are sacrificial plants that you don’t mind the beetles being drawn to. However, to plant trap crops effectively, you have to be willing to sacrifice a particularly favored type of crop plant to the beetles. This can be very effective if you have identified the specific type of flea beetles you’re combating and plant a small area of their favorite food to lure them there, especially if you then destroy them while they’re on the plants.
Get polycultural! Interplant your susceptible crops with ones that aren’t as appealing to the flea beetles and slow down the progress from plant to plant. Sometimes you can even manage to improve the growth of your crop – for instance, planting marigolds around the base of tomato plants can offer some protection from pests while also acting as a beneficial companion plant for the tomatoes. Some plants, such as catnip or basil, even repel the beetles naturally on their own.
Don’t forget to cultivate an environment that’s friendly to beneficial parasitic insects. Braconid wasps and tachinid flies are both predators of the flea beetle, and are more than happy to kill them off for you. They’re also quite useful against tomato hornworms. Unfortunately, you can’t purchase braconid wasps or tachinid flies commercially, but you can lure them by planting flowering herbs and plants that they favor such as dill and yarrow, as the adults of these beneficial predators will feed on the nectar from these plants.
Beneficial nematodes can also assist you in eliminating the larvae while they’re pupating in the soil. These microscopic lifeforms feast on insect larvae, wiping them out quite effectively before they can ever reach adulthood.
Placing yellow sticky traps throughout your yard and garden can be another way to eliminate these pests. Once they’ve made contact with the sticky surface, they’re caught and can’t escape, and then you simply dispose of the trap later once it’s no longer sticky.
And, if all else fails, you could always vacuum them up. Flea beetles are notorious for jumping, and they’re quite small, so they’re hard to hand-pick out of the garden… but a handheld vacuum can suck them up before they can leap away. Just be careful not to vacuum the leaves off your plants too!
Preventing Flea Beetles
Floating row covers such as Harvest-Guard are useful for keeping flea beetles off of young seedlings, provided that they haven’t overwintered in the soil beneath the floating row cover. Prior to planting, till or turn the top few inches of soil, which should cause any flea beetles there to be revealed, and get them out of the way. Then plant your seeds or seedling plants and cover. This is especially effective for non-flowering crops such as radishes or cabbage, but they need to be removed eventually on flowering crops like tomatoes to allow for pollination.
A healthy sprinkling of food-grade diatomaceous earth over the soil and the foliage of your plants can help deter flea beetles. While it’s completely harmless to humans and pets, to small insects, it feels like they’re moving across a field of knives. Since they get cut up so easily by the fine powder, they tend to avoid areas where they will move through it. However, it must be reapplied after rain.
Another powdered application that can be used is kaolin clay. Sold as Surround WP, you can carefully coat your young plants in this clay to deter insects from munching on them.
Something else which is often used as a preventative measure is neem oil. A regular application of this to the leaves and stems of most vegetables will deter a whole host of insect pests, among them aphids, asparagus beetles, potato bugs, and of course flea beetles, as well as many others. The neem cakes that result from the pressing of neem seeds to make the oil are also useful to work into the top of your soil, as they can deter flea beetles from overwintering in your garden bed.
An azadirachtin spray offers a distilled form of the azadirachtin oils that make neem oil such an effective repellent. I recommend Azatrol EC, which is very pure and needs to be thoroughly diluted per the directions before use.
Q: Flea beetles attacking whenever the row cover comes off, help!
A: As long as you’re not a commercial grower, you can likely hand-pollinate your plants and leave the floating row cover in place. It takes a bit more time, but use a Q-tip and gently swab the inside of one flower, then move to the next, and so on and so on. That will ensure your plants are pollinated, all while keeping the flea beetles away.
Q: There are flea beetles killing my lawn. What can I do?
A: For something as large as a lawn, you’re likely going to need to use something like a pyrethrin spray to eliminate the flea beetles. There’s just too much space to cover to opt for preventative measures, and powders like diatomaceous earth are going to get knocked off the grass whenever someone walks over it or whenever you water.
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