This little jumping beetle is particularly eager for the leaves of the vegetable garden, which it cheerfully pierces. Find out how to recognize flea beetles and which natural treatments to use to eliminate them.
Flea beetles: beetles
Flea beetles are between 2mm and 5mm long. They are a black colored back with metallic blue reflections and the rest of the body brown, some species such as Phyllotreta nemorum have a yellow stripe on the back. They have two long antennae, two hard, horny wings. Their hind legs are very developed, they allow them to jump high and have earned them the nickname "land fleas". The larvae are nested underground, they are the adult insects that we observe on the leaves. When disturbed, they drop to the ground. There are several species of flea beetles: cruciferous flea beetles, corn, potatoes, vines ...
Life cycle of flea beetles
After a winter spent underground, or hidden under a pile of leaves, the flea beetles come out of their hibernation in May. Depending on the species, they begin to nibble the leaves of their favorite plants. Females lay eggs at the foot of seedlings to provide food for their offspring. This spawning takes place in the spring, but females also lay underground before winter. The larvae will then enjoy the roots of the young seedlings. They also penetrate plants and dig galleries. The larvae, which hatched in the fall, can even spend the winter in the heart of the plant and emerge in the spring to pupate underground. A female flea beetle can lay up to 1000 eggs ... enough to devastate many crops!
Affected plants and damage
Depending on the species, flea beetles attack cruciferous plants (cabbage, turnip, arugula, etc.), nightshades (tomatoes, eggplants, potatoes, etc.) or even vines. The leaves of these plants are then riddled with small holes, rather circular in shape. Most of the time, they nibble on the young leaves, which are more tender for their taste. You must therefore pay special attention to the seedlings so as not to compromise all your efforts. Adept at dry and hot environments, they carry on with their task until frost.
Preventive control techniques
Certain plants would keep these pests away from the vegetable patch. This is the case of mustard and Chinese cabbage which create a diversion by attracting flea beetles. Conversely, tansy, red fescue or white clover would repel them. They should therefore be placed near plants prone to flea beetle attacks.
A layer of mulch has several roles: conserve moisture, limit the growth of weeds, protect from the cold in winter and from the heat in summer. By keeping the soil cool, mulching will limit soil colonization by flea beetles.
Surely one of the most effective techniques. Automatically install an insect screen on sensitive species. It will also allow you to fight against other pests that would have the bad idea to take a walk around your vegetable garden.
Once the flea beetles are spotted, they must then be scared away. These insects don't like humidity, so get a good cold shower. Then water the whole plant, at the level of the foliage but also on the ground. Preferably in the morning, so that the water evaporates well with the heat of the day and does not induce disease. However, avoid watering tomatoes which can cause late blight.
Even if it means watering, you might as well spray liquid manure which also has the advantage of strengthening the plants. You can then choose between tansy or nettle, leaving a few days between sprays.
Decoctions of garlic or chilli would have a repellent effect! Don't hesitate to spray it all over the plant, it's worth a try.
Some gardeners use strips of glue to capture adult insects. It may not be a stand-alone solution, but it will always be a few less flea beetles!
If you still can't get rid of the flea beetles, use a pyrethrum-based insecticide. Authorized in organic farming, this treatment respects the soil. However, use it only if other treatments have not worked. Indeed, an insecticide, whether natural or not, does not differentiate between pests and auxiliaries ...