Sources: AJC1 from UK, Cabbage-stem Flea Beetle (37130910672), Edited by Plantopedia, CC BY-SA 2.0 (large)/Gilles San Martin from Namur, Belgium, Psylliodes chrysocephala larva (31943790945), Edited by Plantopedia, CC BY- SA 2.0 (small)
Fleas are pests that often go unnoticed because they are so small that they are not noticeable. They can damage young plants so badly that they die.
In a nutshell
- Fleas belong to the leaf beetles
- they live in dry soil and feed on leaf and root tissue
- Overwinter between mulch, wood or in piles of rocks
- Young plants are particularly at risk
- Preventive measures are most important
What are flea beetles?
Despite the name, flea beetles have nothing in common with common fleas. They belong to the leaf beetles and are so small that they are easily overlooked. One characteristic of the beetles, however, is their colorful appearance, ranging from yellow to red to blue. Most of the time, the beetles also have a metallic sheen. Their hind legs are strong and actually allow them to jump, although not as far as fleas can.
damage picture
The beetles and larvae eat both the leaves and the roots. This can be seen from the fact that the plants take care of it. The bites in the leaves look like small holes. Sometimes feeding passages are also recognizable. In older infested plants, the leaves appear shot through with shot. Young plants can die off completely from biting the roots.
Harmful pattern: larvae of the large oilseed rape flea (Psylliodes chrysocephala) on oilseed rape (Brassica napus)Source: Gilles San Martin from Namur, Belgium, Psylliodes chrysocephala larva (31827378971), Edited by Plantopedia, CC BY-SA 2.0
affected plants
The beetles are usually "specialized" in a certain type of plant. That is why there are, for example, potato flea beetles (Psylliodes affinis) or rapeseed flea beetles (Psylliodes chrysocephalus). Overall, however, they can occur on all kinds of plants, including ornamental plants and fruit trees. The following plants in the vegetable garden are particularly badly damaged:
- Cruciferous vegetables: cabbage, arugula, radishes, radishes
- Nightshade: tomatoes, aubergines, peppers
Notice: The young plants of the species mentioned are particularly affected because they still have soft and unprotected shoots and leaves. The beetles and their larvae can completely destroy a young plant stand within a very short time.
Fight
It is not necessary to control all flea beetles. This is only important for infested young plants. However, aids should then be used as quickly as possible.
Plant manure wormwood and tansy
You can easily make your own manure from tansy (Tanacetum vulgare).
A manure made from plant parts not only drives away the pests, but also strengthens the plants. This is particularly important for flea beetles because the beetles feed mainly on soft plants. Wormwood and tansy work well on these bugs, used either alone or mixed.
manual
- About 50 grams of herb are crushed per liter of water.
- Put the plant material in a sufficiently large container. To avoid a strong odor, add some rock flour.
- Top up with the appropriate amount of water. A margin of around 10 cm should remain free, as the liquid manure foams a lot during development.
- Cover jar, but not airtight.
- Stir daily. Fermentation begins when the brew begins to foam.
- The liquid manure is ready when the foaming stops.
- Dilute the liquid manure with water before use. Use one part liquid manure and ten parts water. The agent is filled into a spray bottle and sprayed onto the plants until dripping wet. Or water the plants with it.
- If necessary, repeat the application after a week.
rock powder/algae lime
Dusting affected plants with rock dust protects them from pitting the leaves, but not from damage to the roots.
Notice: Rock flour or algae lime are also remedies against various fungal diseases on the leaves.
promote beneficials
Make sure that predators of flea beetles, such as hedgehogs, feel at home in your garden.
All animals that eat insects are welcome as beneficial insects in the vegetable garden. These include not only hedgehogs, but also shrews and larger species of beetles. Sufficient hiding places should be available for the animal guests.
glue strips
The little bugs can be caught with glue. To do this, wooden boards are coated with glue and placed between the plants. The animals hop or run onto the boards and stick to them. However, it should be noted that other animals could also be caught.
Prevent
While the right response to a flea infestation can prevent worse from happening, early prevention is even better. First and foremost, good care of the plants is helpful:
- water regularly, the pests do not like damp soil
- Keeping the soil loose, hoeing from time to time disrupts the development of the beetles
- mulching prevents penetration into the soil
- need-based fertilizing vigorous plants
Other recommended preventive measures include:
cultural protection networks
Small vegetable patch with protective net
They are available in different versions, for the tiny beetles the mesh size has to be very small (less than 1 mm). Protective nets only work if they are attached really close to the crop, because the pests use every loophole. They also have the disadvantage of having to be removed and reattached every time you tend to the plants.
mixed cultures
Combining different types of vegetables with each other fulfills two tasks. On the one hand, the vapors from the plants can deter pests, on the other hand, pests are distracted from their actual goal. Mixed cultures with spinach should work well for flea beetles. It is also important to change the cultivation site every year.
Early sowing
With fruit vegetables it makes sense to only place strong young plants outdoors, then they are no longer so attractive to flea beetles. Cultivation on the windowsill or under glass is suitable for this.
frequently asked Questions
How do flea beetles reproduce?They lay eggs that hatch into larvae that feed on plant parts. The larvae pupate in the soil. This is why regular chopping is so important, because it disturbs the animals during pupation and makes it easier for beneficial insects to find the larvae and pupae.
Do flea beetles also occur in greenhouses?The pests can also invade greenhouses or cold frames, but are easier to control there.
Are older plants at risk?They can be attacked by flea beetles, but the damage is limited and is more of an optical problem.