How to Identify and Get Rid of Flea Beetles
The flea beetle is a horrible plague in all gardens. If you spot damage, it's important to act quickly. Find out how to eliminate these pesky little beetles with this helpful guide by Epic founder Kevin Espiritu!
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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. This is not the pest that bites your dogs and cats (and sometimes you).
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? Most importantly, how do you kill them before they can devour your prized vegetable plants?
Today, I’m going to teach you all about flea beetles, help you identify feeding, tell you how to wipe them out, and hopefully answer all your questions.
What are Flea Beetles?
There is a wide diversity of beetles considered to be flea beetles. In scientific taxonomy, these species 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, I’m going to focus primarily on those that impact agricultural crops, especially food crops.
Types of Flea Beetles
Before I start, I did want to mention that there are a few species that are considered beneficial. They tend to consume weeds rather than food crops. However, their beneficial use is incredibly limited.
Crucifer Flea Beetle
Like both cabbage worms and cabbage loopers, this beetle tends to be attracted to cruciferous plants of the family Brassicaceae. This small black beetle is local to the northern United States.
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.
Striped Flea Beetle
Like the crucifer, 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.
Western Black Flea Beetle
These small beetles are a shiny black color and tend to live in the western United States and prefer Brassicaceae plants.
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.
Potato Flea Beetle
The potato flea beetle is very tiny and shiny black in coloration. They prefer Solanaceae plants such as potatoes and tomatoes. They are generally found east of the Rocky Mountains in the United States.
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.
Tuber Flea Beetle
A major problem in the Pacific Northwest, the tuber flea beetle feeds on Solanaceae plants, but is drawn mostly to the tuberous roots. They are a dingy, almost matte black color.
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.
Pale Striped Flea Beetle
Primarily a pest in warmer parts of the United States, the pale striped flea beetle has an incredibly wide diversity of host plants. This makes it one of the most dangerous, especially in agricultural areas such as California, where it’s common. Visually it looks quite similar to the horseradish beetle, a black beetle with off-white crescent-shaped stripes along its sides.
Life Cycle
In the winter, flea beetles overwinter in their adult form. Adults often hide under leaves or dirt clods or in protected areas. Once warmer weather comes in the spring, they begin to emerge over a couple of weeks.
Adults 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, which is a risk factor to root crops, most larvae are not particularly harmful to plants.
After several weeks, the larvae will pupate under the soil’s surface. Once the pupal stage has concluded, they emerge from the soil as adult beetles and begin the life cycle again.
The adult phase is when flea beetle damage is most prevalent. Most types will produce at least two generations in a year. In warmer climates, three or more generations are possible.
Common Habitats
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 they can hide beneath. In gardens, this leaf litter or beneath dirt clods and rocks are ideal.
It can be easy to identify an area where feeding is widespread, as they cause extensive damage to the leaves of their favorite plants. 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. Management is important because they’re avid consumers of various vegetable crops.
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. Feeding in this case occurs on eggplant, potato, tomato, pepper, and other members of the Solanaceae family. Potato flea beetles are Epitrix species, for instance.
Palestriped flea beetles feed almost indiscriminately, leaving damage on a wide range of plants. This Systena species beetle will consume most Solanaceae family plants, or vegetable crops (tomato, potato, eggplant, pepper, etc), along with cotton, grape, pea, peanut, corn, oat, strawberry, pumpkin, and pears. This makes them particularly dangerous agricultural pests.
How To Get Rid Of Flea Beetles
While there are a diverse number of species considered flea beetles, all of them are vulnerable to the same control methods. Let’s look at the different measures you can take to limit damage and get rid of them.
Environmental Control
One good option to combat the flea beetle is to plant trap crops that can handle injury before you decide to destroy them. In essence, these are sacrificial plants you don’t mind being eaten.
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 beetles you’re combating. Plant a small area of their favorite food to lure them there, then destroy them while they’re on the plants.
Interplant your susceptible crops with ones that aren’t as appealing. This slows down the progress from plant to plant. 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 they favor, such as dill and yarrow. 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 before they can become adults.
Placing yellow sticky traps throughout your yard and garden is another way to eliminate these pests. Once they’ve made contact with the sticky surface, they’re caught and can’t escape. Simply dispose of the trap later once it’s no longer sticky. Note that these will trap other insects as well, even beneficial ones.
Prevention
Floating row covers are useful for keeping beetles off of young seedlings, provided that they haven’t overwintered in the soil beneath the floating row cover.
Before planting, till or turn the top few inches of soil. This should cause any beetles to be revealed so you can remove them. Then plant your seeds and cover. This is especially effective for non-flowering crops such as radishes or cabbage. However, 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. Since they get cut up so easily by the fine powder, they tend to avoid areas where they will move through it.
Another powdered application that can be used is kaolin clay. Carefully coat your young plants in this clay to deter insects from munching on them.
Something else often used as a preventative measure is neem oil. A regular application of this to the leaves and stems of most vegetable crops 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.
Frequently Asked Questions
How do I stop flea beetles from attacking whenever the row cover comes off?
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. That will ensure your plants are pollinated while keeping the beetles away.
There are flea beetles killing my lawn. What can I do?
For something as large as a lawn, you’re likely going to need to use something like a targeted spray to eliminate the 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.