Flea beetles, or flea beetles

Flea beetles are having a great time with the heat wave.

Indeed, it is in these particularly hot and dry conditions that this insect multiplies.

With good visibility (flea beetles are less than 5mm) you may be able to see these critters jumping like cabbage fleas in cabbage, for example.

But their presence is mainly characterized by leaves full of small holes…

Before we see how to prevent flea damage to our crops, let’s start by getting to know this insect a little better.

Presentation of the flea beetle

The flea beetle (subfamily Alticinae) is a small beetle measuring 1.5 to 5 mm, depending on the species.

There are different types, in different sizes and colors, but in common:

• highly developed hind legs, which allow them to make long jumps, hence their nickname of flea beetles.
• long antennae, useful for spotting their favorite foods
• wings, hidden under elytra, allowing them to travel hundreds of meters to taste these dishes…

Each species has its host plant (or its kind of host plant).

Here are the main species that are widespread in vegetable gardens in France, and more generally in Europe:

What damage do flea beetles do to our crops?

Flea beetles appreciate warm and dry situations (which will be useful to us below).

Also, the “attacks” are especially noticeable in the middle of summer.

But it can start in the spring (more or less early depending on the weather) and last until the fall (it also varies depending on the weather, but also on the species).

The flea beetle gnaws the leaves of its host plants and tears them with small round holes.

Heads (head cabbage) or inflorescences (cauliflower, broccoli, Roman cabbage) can also be affected.

When virulent, these attacks have the following consequences:

• a weakening of the plant (the tissues are severely damaged, the leaf can eventually dry out)
• disturbed development (less healthy leaf surface = less photosynthesis)
• reduced harvests, and especially depreciated (plant no longer very presentable… even though it remains perfectly edible)

as a preventive

• Promote biodiversity in your garden by planting hedges (for birds or hedgehogs in particular), by digging a pond (to house bats, fond of flea beetles), by placing heaps of stones (reptiles) or simply by conservation of wild areas…
• Keep the soil cool, especially with a good mulch, but also by watering more often than usual (early morning or late evening) if the weather is conducive to a proliferation of flea beetles
• Plant repellent flowers (marigold, cosmos) here and there in your vegetable garden
• Plant lettuce in combination with cabbage, turnips, radishes
• As a preventive measure, if conditions are right, spray a decoction of tansy
• Within sensitive crops, place branches of repellent plants such as broom or rosemary in particular
• Place an insect screen, with very fine gauze (2 mm)

• Water the foliage of sensitive plants with a fine spray (the flea beetles will go elsewhere, but come back a few hours later… repeat until you discourage them)”, or with a more aggressive spray (the message is immediately more clear. .. but avoid doing it on fragile plants)
• Spray a decoction of tansy
• Spray undiluted wormwood fertilizer (preferably prepared with dry leaves)
• Sprinkle with a manure of cabbage leaves, here is the recipe:

cabbage leaf manure

• In a plastic container, macerate 3 kg of well-coloured fresh leaves in 10 liters of water
• Cover a vent
• Stir daily until the bubbles disappear
• Filter
• Water at the base with 5 times diluted fertilizer (i.e. 1 liter of fertilizer for 5 liters of water) every 3 or 4 days as long as you see fleas (or new damage)

And are your crops affected at home?

How do you react?

Do you have any tips or recipes to share?