Ground fleas: recognise, prevent and fight

Here you can find out how to recognize the flea bug, how to prevent it and why it is difficult to combat with natural means or insecticides.

Have you discovered many small holes in the leaves of your young plants? This speaks for an infestation by flea beetles. We will show you how to prevent an infestation or how to recognize it early and explain what options are available to combat it.

Earth fleas: features and way of life

the flea (Psylliodes) is actually not a flea at all, but a leaf beetle (Chrysomelidae). The confusing name probably comes from the fact that the beetle has extremely powerful hind legs. With these, the leaf beetle can jump very far, like a flea. Other distinguishing features are the species-specific dark brown to black coloration and the size of about three millimeters.

With the first warm days of spring, the females lay their eggs close to the ground on plants or directly in the ground. After less than two weeks, the larvae hatch and feed on roots in the soil. The resulting damage usually does not affect the plant. The larvae pupate in early summer and the adult beetles hatch in June to August. Depending on the weather, up to two generations can be run through in one year. The adult beetles hibernate in the ground, in hedges or in dead plant parts on the surface.

Recognizing flea: Damage, bites and Co.

Beetroot fleas prefer soft plant tissue and therefore particularly like to eat young leaves of vegetable plants. The gardening season has only just begun and you can already see the first damage caused by feeding on your young cabbage plants? If you find lots of small, about 1/4-inch, sieve-like holes in your cabbage leaves, you have a flea infestation. Cruciferous plants (Brassicaceae), such as radish (Raphanus sativus var. sativus), arugula (Eruca sativa) and the whole range of cabbages, for example Chinese cabbage (Brassicarapa subsp. pekinensis), white cabbage (Brassica oleracea convar. capitata var. Alba) and Brussels sprouts (Brassica oleracea var. gemifera), can be of the flea species Psylliodes chrysocephala be infested. Also nightshade plants (Solanaceae), such as potatoes (Solanum tuberosum), eggplant (Solanum melongena) and tomatoes (Solanum lycopersicum) can be damaged. Here is mostly the flea type Psylliodes affinis the culprit. Symptoms can appear throughout the gardening season, but a heavy flea infestation, especially in spring, can severely weaken young plants. Dry weather in April and May increases the occurrence of flea beetles.

Fleas cannot infest mammals like humans. But when the little beetles land on our skin, their saliva can cause skin irritation. Such flea bites can cause small red rashes. In non-allergic people, however, these are harmless.

Prevent flea beetles

Since flea beetles are difficult to control, preventive measures are very helpful. Using a close-meshed vegetable protection net can effectively protect your vegetable plants from the small bugs. To do this, however, the net must be attached to the ground in such a way that there are no gaps. If the bed is already infested, the measure is unfortunately ineffective because the beetles then come directly out of the ground.

In addition, you should regularly remove weeds in the bed that has not yet been planted, especially in spring. This deprives the beetles of their food base in the spring before you sow or plant your crops. Regular watering during dry periods also helps to reduce the risk of infestation, because flea beetles feel particularly comfortable in dry soil.

Mixed cultivation of endangered plants with onions or garlic can also prevent an infestation. Fleas are naturally repelled by onions and garlic. We also recommend that you do not plant particularly endangered plants in the same place every year. A varied crop rotation keeps flea beetles and many other pathogens in check.

Preparing young plants in a sheltered greenhouse or on the windowsill instead of direct seeding is a very good way to minimize flea damage. The flea beetles are particularly interested in small plants and rarely attack larger leaves that are far away from the ground.
Rapid seedling development is crucial to prevent severe flea damage. You can ensure rapid growth of your young plants with an optimal supply of nutrients. For this we recommend a primarily organic long-term fertilizer. Our Plantura organic tomato fertilizer provides an optimal ratio of the most important nutrients for your vegetable plants.

Notice: A natural balance between predators and the beetles is important to prevent flea beetles from multiplying quickly. For example, predatory beetles and hedgehogs eat flea beetles. With a shelter made of piled up leaves and twigs you offer a shelter to many useful insects and also to the hedgehog. Anyone who has opted for a natural garden design will have fewer problems with flea beetles.

How to prevent flea beetles:

• A close-meshed net keeps the beetles away, provided they are not yet infested
• Regular weed control in spring
• Don't let the soil dry out
• Mixed cultivation with onions and garlic
• Varied crop rotation
• Preferring young plants instead of direct sowing
• Beneficial insects in the garden support financially

fight flea beetles

Fighting flea beetles is difficult. But there are biological options that can help if an infestation is detected early.

Fight flea beetles biologically

Fleas are very difficult to get rid of. It is therefore particularly important that you regularly check your young plants, especially cabbage plants, for infestation by flea beetles from April onwards so that you can react quickly.
In the case of a mild flea infestation, dusting infested young plants with rock dust can help. This is very easy to do by putting some rock dust in a fine sieve and waving it over the plants - this way the plants are evenly dusted with rock dust. Applied once a week, the rock flour spoils the beetles' appetite for the young plants.

There are hardly any biological preparations to combat flea beetles. While pyrethrin-based products combined with canola oil can be derived from plants, pyrethrins can be harmful to beneficial insects in your garden. We therefore recommend that you take preventive measures and reduce the use of such agents to a minimum.
A biological measure is the use of Nematodes as beneficial insects against flea beetles. The small threadworms are harmless to humans and infest the larvae of flea beetles in the soil. The nematodes use the larvae to reproduce and kill them in the process. You can order such nematodes in specialized online stores. These are usually delivered in the form of a powder, which you can simply stir into the irrigation water.

Fight flea beetles chemically

No synthetic pesticides against flea beetles are currently approved in Germany. We therefore recommend preventive measures and regular inspection of your young plants. In this way, you can take countermeasures at an early stage with natural means.

Home remedies for flea beetles

If you have a mild flea infestation, you can try using home remedies to prevent a more severe infestation.
A broth of onions and garlic can drive away flea beetles. To do this, add about 50 grams of garlic or onions to one liter of boiling water. After boiling, the brew can be sprayed on the infested plants.
A decoction of wormwood and tansy can also help against flea beetles. To do this, about ten grams of the dried herbs are brewed with one liter of boiling water. The cold brew can also be applied to the affected plants.

Fleas feel particularly comfortable in dry soil. If you want to protect your soil from drying out too quickly, you can use the Use of mulch well advised. Check out our article on mulching to learn how mulching materials can benefit your soil and plants.