Tony O’Neill, gardener and author of the popular “Composting Masterclass” and “Your First Vegetable Garden,” combines lifelong passion and expert knowledge to simplify the art of gardening. His mission? Helping you cultivate a thriving garden. More on Tony O’Neill
If your plant leaves, especially young plants, look like they have been shot with buckshot, there is a good chance you’ve got one of the many types of flea beetle pests in your garden.
Flea beetles are distinct in their small size and disproportionately larger hind legs. They’re called flea beetles because, like flees, they jump. Most species of flea beetles attack only one plant group (or closely related groups), making general identification easier.
There are several insect species referred to as flea beetles. Let’s explore some of the most common species, their preferred food sources, and how to manage them effectively. In farming operations, the damage caused by flea beetles is often not worth the cost of managing them using insecticides.
The adult beetles chew small holes through the leaf, leaving wounds that resemble buckshot holes. Most flea beetles’ larvae, or early stages, eat roots, but as they mature move to chew the leaves on your plants.
Damage from flea beetles is inclined to affect younger plants and seedlings. In severe infestations, plant growth is impeded as the plant’s photosynthesis activity is damaged. In extreme cases, the plant can die.
More than anything, the aesthetic appeal of the plant is affected.
Later in the article, a table lists the various species of flea beetles. Despite the considerable overlap in preferences, each variety of flea beetle has a clear favorite plant.
For instance, certain flea beetles solely consume potatoes, tomatoes, and other nightshade plants, while others enjoy eating cruciferous vegetables like broccoli, cabbage, and others. Mustard is often used as a trap crop for these beetles, drawing them away from cash crops.
Identifying a Flea Beetle
Adults typically range from the fifteenth to a sixth of an inch long. Their hind legs are significantly larger than the front ones. Colors include brown, green, metallic blue, to black; they may have stripes or spots. Flea beetles feed on foliage and occasionally cause severe damage.
Eggs are laid in the soil at the base of host plants, are elliptical in shape, one sixty-fourth of an inch tiny, and white to yellowish-gray.
Larvae cause the most damage to potato tubers (and possibly carrots). The little worm-like larvae have white bodies with brown heads.
Pupa can be found several inches deep in the soil.
Flea Beetle Life Cycle and Habits
Most flea beetle species overwinter in the adult stage, and adults reside in field rows, roadsides, and other protected areas to overwinter.
In the spring, the adults migrate out of their overwintering site as soon as adequate vegetation is available for feeding and egg deposition.
A few flea beetles have larvae that grow on plant leaves. A flea beetle with this behavior is the apple flea beetle, which has larvae that grow on evening primrose.
The larvae of the various flea beetle species are black or gray and have short legs. Instead of shotholes, the larvae make big, uneven leaf holes.
The larger varieties of flea beetles, the apple flea beetle being the most prevalent type, can grow on leaves, and adults chew in a more generalized manner rather than making shotholes.
Only one generation of flea beetles with larvae that grow on leaves occurs yearly, although the adults may remain visible for several months.
Although flea beetles are ubiquitous, the damage they cause to plants is frequently negligible. Before any impact on output on established plants, 20–30% or more of the leaf area must have been eaten.
The garden plants most likely to gain from treatment are more delicate seedlings, ornamental or food-grade plants, and potatoes that tuber flea beetle larvae may harm.
The flea beetles’ rapid movement can make management more difficult. Understanding their nature and life cycle will make it easier to choose the best tactics, actions, and times to lessen their negative effects when gardening.
Cultural, physical, biological, and chemical methods should be employed to manage flea beetles when necessary.
How To Spot & Control Beetles
Scout for Flea Beetle
Watching for adult flea beetles on sensitive plants is critical, especially during springtime management. Until they go through their susceptible period, check on seedlings at least twice a week.
A pest treatment recommendation is 1 to 5 flea beetles per plant due to the potential severity of harm to seedlings.
When flea beetle levels are high or on mature plants that are more vulnerable to eating, such as ornamentals and leafy greens, treatment may be required.
Sticky Traps for Beetles
Sticky traps are a monitoring tool that indicates when and how many adult flea beetles are present, but they are inefficient at controlling populations. Remember that they will also draw some helpful insects, such as pollinators when considering their use.
Sticky Traps For Beetle Larvae
Flea beetle larvae can get caught in traps. However, it is very unlikely this will help control the levels on your plants while gardening.
Cultural and Physical Controls
Adjusting planting times in your garden to avoid peak adult activity periods will lessen plant injury and improve tolerance to feeding injury.
Planting early under protective covers and soil-warming mulches advances plant maturity before flight peaks and increases plant tolerance.
Promote healthy, fast-growing plants when gardening by ensuring the seedbed is well-prepared and that essential nutrients, ample compost, and water are available—healthy plants grown in well-drained, healthy soil rich in organic matter.
Trap Crops to Reduce Beetles
Plants that flea beetles find attractive can be used as a trap crop. These crops are better when they are larger; well-kept trap crops are more alluring to flea beetles; plant the trap crop 2 to 4 weeks before the cash crop. Chinese southern giant mustard illustrates crops that work well as a flea beetle trap.
Insect pests can be confused, repelled, or prevented from finding hosts by companion plants. Marigolds, dill, and green onions are a few companion plants used when planning your gardening management to reduce adult flea beetle levels.
Plants that can be interplanted with or under-sown in cash crops include legumes like vetch and clover. These mulches can hide host plants from flea beetles and offer habitats for helpful insects that live below the ground, like predatory ground beetles.
Good sanitation techniques when gardening is crucial to lowering overwintering adult flea beetle numbers because adults hide under soil clods and plant detritus.
In the fall, you can remove or destroy refuge habitats by rototilling or plowing crops, residues, and weeds. Those in the mustard family are among the most troublesome weeds.
Floating Row Covers
Light, water, and air can pass through row coverings. Plants are physically protected from pests, insects, illnesses, and environmental pressures like frost by row covers. Row covers can also prolong the growing season by retaining heat.
It is crucial to remember that flea beetles can emerge from under row covers installed where host crops flourished the previous year and can overwinter in gardens (under soil clods, plant debris, and weeds).
Parasites and Predators
Adult flea beetles are consumed by generalist predators such as lacewing larvae, big-eyed bugs, and damsel bugs. Parasitoid wasps can also kill some kinds of adult flea beetles. These helpful insects are drawn to plants that produce nectar and pollen, such as anise, chamomile, clover, dill, and marigold.
Entomopathogenic nematodes are soil-dwelling parasitic worms that kill insects that live in the soil, including flea beetle larvae.
Are Nematodes Good or Bad for Dealing With Adult Flea Beetles?
People worry when gardening about nematodes; they hear that they will attack plants too. It is important to recognize there are many species of nematodes, some are good, and others are bad. The good ones can be used for controlling adult flea beetles and slugs.
The fungus Beauvaria bassiana is responsible for white muscadine disease, which can lower flea beetle numbers. When fungal spores are in touch with insects, they stick to the insects, germinate, and penetrate their bodies.
Applying commercially prepared B. bassiana preparations in the evening and in humid conditions will increase their effectiveness because sunshine can dry up and kill spores.
The damage caused by flea beetles seldom warrants chemical intervention. If you do use pesticides, read the label instructions very carefully. Ensure that any flea beetle pesticides you are considering are legitimately registered for use on the crop.
Common Flea Beetle Species
With so many flea beetle species seen when gardening, such as The striped flea beetle, Potato flea beetle, crucifer flea beetle, and pale striped flea beetle. I thought it would be a good idea to compile a table below to help you identify and name the adult flea beetles you may notice while gardening.
|Comments & Host Plants
|Apple flea beetle
|Wide range of hosts, mostly members of the cabbage family of plants (Cruciferae family). The state’s most destructive flea beetle species is the western black flea beetle. Two generations, and occasionally three, are normal. Early season hosts for these insects include winter annual mustards like flixweed.
|Cabbage flea beetle (western black flea beetle, crucifer flea beetle)
|Phyllotreta pusilla, P. cruciferae
|Sweet corn, soybeans, sorghum, small grains, and several vegetable crop species (particularly those in the nightshade and cabbage families). Because they can spread Steward’s disease (bacterial wilt), flea beetles are a problem in the cultivation of corn.
|Corn flea beetle
|Wide range of hosts, mostly members of the cabbage family of plants (Cruciferae family). The state’s most destructive flea beetle species is the western black flea beetle. Two generations, and occasionally three, are normal. Early-season hosts for these insects include winter annual mustards like flixweed.
|Desert Corn Flea Beetle
|Primarily corn, but also wheat, barley, sorghum, sudangrass, sugarcane, and other grass crops
|Elongated flea beetle
|It closely resembles the pale-striped flea beetle, with similar hosts.
|Hop flea beetle
|cucumber, strawberry, tomato, beet, strawberry, hops, and cabbage. One of the earliest springtime beetles to emerge
|Horseradish flea beetles
|Phyllotreta armoraciae, P. albionica
|Horseradish, occasionally other mustards.
|Leafy spurge flea beetles
|Aphthona flava, A. lacertosa, A. nigriscutis
|Younger larvae develop on roots and late stages burrow into the crown of the plant.
|Palestriped flea beetle
|Mainly Amaranthus species like pigweeds. Occasionally, hosts include beets, spinach, Swiss chard, lettuce, and allied plants.
|Potato flea beetles
|Epitrix cucumeris, E. subcrinita, E. parvula
|It has the broadest range of hosts among all flea beetles, including weeds, squash, beans, corn, sunflowers, lettuce, and potatoes.
|“Spinach flea beetles,” including the three spotted flea beetle
|Disonycha triangularis. D. xanthomelas, D. collata
|“Spinach flea beetles,” including the three spotted flea beetle
|Sumac flea beetle
|Currant, skunkbush, sumac.
|Tobacco flea beetle
|Various plants from the nightshade family, such as eggplant. Most typical in warmer regions
|Toothed flea beetle
|Corn and other grasses
|Tuber flea beetle
|Potatoes. Larvae are associated with tuber injuries.
Frequently Asked Questions
How do I identify a Flea Beetle?
Most adult flea beetles are small, darkly colored, occasionally shiny or metallic, jumping quickly when frightened. Flea beetles have several varieties.
Which plants are most susceptible to flea beetles?
Brassica (cabbage family) and solanaceous (nightshade family) plants’ foliage, as well as other root crops like potato tubers, are all susceptible to attack by flea bugs.
When are plants most susceptible to flea beetles?
Young vegetable seedlings are especially vulnerable to adult feeding harm, frequently appearing as tiny shotholes and pitting in leaves and cotyledons.
Which are the best ways to manage flea beetles?
The most effective management methods are row covers, trap crops, mulches, and sanitation.
Other Pests To Watch For In The Garden
Flea beetles are a nightmare when it comes to damaging your plants, But there are so many more pests and diseases, such as Whiteflies, Fungus Gnats, Hornworms, Termites, Rats, Blackflies, Aphids, Allium Leaf Miner, Ants, Thrips, Slugs, and Spider Mites, just to name a few.
Learning each of these pests and how to deal with them can greatly increase your chances of having a successful garden.
Flea beetles can cause harm to crops in the brassica and nightshade families, but by following best gardening practices like composting, mulching and hygiene, these pests can be managed. Before using insecticides, consider the impact on the soil biota.