Flea Beetle
Pest · Commonly affects: Rocket, Radish, Cabbage, Kale, Pak choi, Mustard leaves
Flea beetles are tiny jumping beetles that can turn healthy brassica and salad seedlings into lacework within days. They are most troublesome in warm, dry spring weather, when slow-growing young plants are vulnerable. Established crops usually tolerate some feeding, but repeated attacks can check growth and spoil leaves for the kitchen.
How to identify it
Adults are shiny black, bronze or dark-striped beetles, usually 1.5-3 mm long. They spring away like fleas when disturbed, especially on sunny days. Look for numerous neat, round holes, often called shot-holes, scattered through cotyledons and young leaves. Damage is most obvious on rocket, radish and brassica seedlings. The beetles may be hard to see because they drop to the soil or jump away as soon as foliage is touched.
Damage
Adults chew small holes through leaves, reducing the leaf area available to young plants. Heavy feeding can stunt or kill tiny seedlings, particularly in dry soil or during a prolonged cool spell. On rocket, mustard leaves and radishes, even moderate shot-holing can make crops unattractive to harvest. Older, vigorous plants normally outgrow the damage.
Prevention
Sow little and often so that seedlings do not all meet the highest-risk period together. Keep seedbeds moist, weed-free and fertile enough for rapid growth, without overfeeding. Cover susceptible crops immediately after sowing or planting with horticultural fleece or fine mesh, securing all edges. Grow rocket and oriental leaves in containers or under cover where practical, and rotate brassicas and salad beds between seasons.
How to manage it
Check seedlings frequently in warm weather and replace plants that are badly checked while there is still time to resow. Water in the morning to maintain steady growth and harvest damaged salad leaves promptly. Keep protective covers in place until plants are robust, lifting them briefly only for weeding. Encourage garden birds, ground beetles and other wildlife with varied planting and shelter, although barriers remain the most reliable protection for seedlings.
Flea Beetle: frequently asked questions
How do I identify flea beetle?
Adults are shiny black, bronze or dark-striped beetles, usually 1.5-3 mm long.
How do I prevent flea beetle?
Sow little and often so that seedlings do not all meet the highest-risk period together.
How do I get rid of flea beetle?
Check seedlings frequently in warm weather and replace plants that are badly checked while there is still time to resow.
General guidance for UK home gardens and allotments, focused on prevention and non-chemical control. For a confirmed diagnosis, the RHS or a local garden centre can help. Page updated 19 Sep 2026.