Earth fleas: recognize, prevent & fight

Here you will find out how to recognize the damage caused by earth fleas, how to prevent them and why they are difficult to control with natural agents or insecticides.

Have you discovered many small holes in the leaves of your young plants? This suggests an infestation by fleas. We will show you how you can prevent an infestation or identify it at an early stage and explain which options are available for combating it.

Earth fleas: characteristics and way of life

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

With the first warm spring days, the females lay their eggs near 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 overwinter in the ground, in hedges or in dead parts of plants on the surface of the earth.

Recognize flea: damage, bites and Co.

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 to your young cabbage plants? If you find many small, sieve-like holes about four millimeters in size in your cabbage leaves, it is a flea infestation. Cruciferous family (Brassicaceae), such as radish (Raphanus sativus var. sativus), arugula (Eruca sativa) and the whole range of cabbage plants, for example Chinese cabbage (Brassicarapa subsp. pekinensis), White cabbage (Brassica oleracea convar. capitata var. alba) and Brussels sprouts (Brassica oleracea var. gemmifera), may be of the flea species Psylliodes chrysocephala be infested. Also nightshade family (Solanaceae), like potatoes (Solanum tuberosum), Eggplant (Solanum melongena) and tomatoes (Solanum lycopersicum) can be damaged. This is mostly the flea species Psylliodes affinis the culprit. The symptoms can appear over the whole gardening season, but especially in spring a strong infestation by fleas can severely weaken the young plants. Dry weather in April and May increases the incidence of fleas.

Earth fleas cannot attack mammals like us humans. But when the little bugs 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 earth fleas

Since the earth flea is difficult to control, preventive measures are very helpful. The use of a close-meshed vegetable protection net can effectively protect your vegetable plants from the small beetles. 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, as the beetles then come straight from the ground.

In addition, you should regularly remove weeds from the bed that has not yet been planted, especially in spring. This deprives the beetles of their food source in the spring before sowing or planting your crops. Regular watering in dry periods also helps to reduce the infestation pressure, because the fleas feel particularly comfortable in dry soil.

Mixed cultivation of endangered plants with onions or garlic can also prevent infestation. Fleas are naturally driven away 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 fleas and many other pathogens in check.

Growing young plants in a sheltered greenhouse or on the windowsill instead of direct sowing is a very good way of keeping the damage caused by fleas to a minimum. The fleas are particularly targeting small plants and hardly infest larger leaves away from the ground.
Rapid young plant development is crucial to prevent severe damage from fleas. 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 vegetables.

Note: To prevent earth fleas from multiplying quickly, a natural balance between predators and the beetles is important. Predator beetles and hedgehogs, for example, eat fleas. With a shelter made of piled leaves and twigs, you offer many useful insects and also the hedgehog a shelter. Anyone who has decided on a natural garden design will have fewer problems with fleas.

How you can prevent earth fleas:

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

Fight fleas

Fighting fleas is difficult. But there are biological possibilities that can help if an infestation is discovered early.

Fight earth fleas biologically

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

Biological preparations for fighting fleas are hardly available. Products based on pyrethrins in combination with rapeseed oil can be obtained from plants, but pyrethrins can harm the 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 fleas. The small roundworms are harmless to humans and attack the larvae of the earth flea in the ground. The nematodes use the larvae to reproduce and kill them in the process. You can order such nematodes in specialized online stores. Usually these are delivered in the form of a powder, which you can simply stir into the irrigation water.

Fight fleas chemically

No synthetic pesticides against fleas are currently permitted in Germany. We therefore recommend preventive measures and regular control of your young plants. In this way, you can take countermeasures with natural remedies at an early stage.

Home remedies for fleas

In the case of a slight infestation by fleas, you can try to prevent a stronger infestation with home remedies.
A stock of onions and garlic can drive away fleas. To do this, add about 50 grams of garlic or onions to a liter of boiling water. After boiling, the brew can be sprayed onto the infected plants.
A brew of wormwood and tansy can also help against fleas. For this, about ten grams of the dried herbs are brewed with one liter of boiling water. The cold brew can also be added to the infected plants.

Ground fleas feel particularly comfortable in dry soils. Anyone who wants to protect their soil from drying out too quickly is with the Use of mulch well advised. You can learn how your soil and plants benefit from mulching materials in our article on mulching.