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Fight grubs in the lawn successfully

Some grubs can cause massive damage and destroy entire lawns. This is how you act effectively against the beetle larvae.

The larvae of many species of beetles are called grubs. Especially the larvae of the cockchafer (Melolontha), the June beetle (Amphimallon solstitiale) and the garden leaf beetle (Phyllopertha horticola). All three belong to the scarabaeidae family and can cause great damage to domestic lawns. However, there are also beneficial insects among the grubs, some of which are even protected. We'll tell you how you can recognize the pests and how you can take action against them.


Distinguish white grubs: Characteristics of the noxious grubs

It is important that you properly identify the harmful grubs first. Each species has distinctive features that you can quickly recognize with the necessary prior knowledge. We'll tell you how to correctly identify the unpopular guests in your garden and differentiate them from beneficial insects.

The grub of the Cockchafer becomes up to four inches long. Its expected life is between three and four years. The cockchafer grub is relatively evenly shaped over the entire body and has a slightly yellowish color. Depending on the stage of development, this color can darken a little (towards brownish). The cockchafer's grub is characterized by strong mandibles (mouth tools) and pairs of legs on the foreleg.

The grubs of the June beetle look very similar to those of the cockchafer, but are slightly smaller. They are usually indistinguishable from laypeople. The so-called locomotion test should also help the untrained eye to differentiate between the grubs of the two species. If you put the larvae with their backs on a smooth surface (for example a pavement slab), you should be able to tell from the type of movement which grubs are involved. The cockchafer grub should curl up on its side while lying on its side. The larvae of the June beetle, on the other hand, should stretch and then try to crawl.

The grubs of the Garden beetle are not as evenly shaped as those of the May and June beetles. While they are rather narrow on the foreleg, the abdomen thickens with increasing length. The garden leaf beetle grubs are bright white in color, but sometimes have grayish shades. Your mouthparts and legs look rather small, but are all the more powerful. In the "locomotion test", the garden leaf beetle's grub attracts attention with its caterpillar-like movements.

Danger: Be sure to identify your grubs before taking any action. In the case of the little animals, for example, the larva of the rhinoceros beetle (Oryctes nasicornis) act. This is a beneficial insect and is under nature protection.

White grubs in the lawn: symptoms of damage

You can tell that your own lawn is infested with grubs if the grass plants appear to be dying off over a large area. Note: The death of the lawn can of course also have other causes, which is why you should reiterate this assumption. Simply dig up a small portion of the dead area and search the excavation for larvae.

The grubs move a few centimeters underground and feed on rotting but also fresh plant material. It can happen that, in the event of a large number of infestations, entire sward are eaten up. What remains is a brown and dry meadow.

Secret tip: The females of the grubs prefer to fly to short-mowed lawns to lay their eggs. So if the females appear heavily in the "cockchafer years", you should stop mowing the lawn for about three weeks.

Fight grubs in the lawn successfully

The best way to prevent grubs is to encourage their enemies in your own garden. A cozy, "untidy" corner in the garden attracts hedgehogs and birds, which then willingly take care of the white grubs. And the mole also likes to eat grubs. A less conspicuous opponent is the insect-infecting fungus Beauveria brongniartii. It occurs in most soils and attacks the grubs there. He grows through these with his mushroom mycelium and kills them in the process. Beauveria brongniartii unfortunately cannot be specifically settled by private users, but is favored by a moist soil. At the same time, white grubs prefer dry locations. In the long term, it therefore makes sense to improve dry sandy soils by building up humus so that they also store moisture in summer.

Fight grubs with nets

If you observe a strong flight of cockchafer in a "cockchafer year", then you can cover your lawn with close-meshed nets or tarpaulins. The beetles' flight time lasts about three weeks. Meanwhile, you should prevent the female beetles from laying their eggs in your lawn. Of course, covering the lawn is only an option for smaller areas. If you use a tarpaulin, it is also necessary to uncover the area for a few hours every day so that the lawn does not die from lack of light.

Fight grubs with nematodes

In the case of acute infestation, however, the methods mentioned above do not really help. The most effective way to control grubs is with nematodes. Nematodes are tiny beneficial insects that parasitize and kill the beetle larvae. However, the little helpers can only be used effectively in young larval stages, which is why the correct application time should be observed. Control with nematodes between July and September is ideal.

Furthermore, you have to make sure that you choose the right nematode species so that beneficial organism-host interaction can take place. For example, our Plantura HB nematodes of the species Heterorhabditis bacteriophora work reliably against grubs in the lawn. To use the beneficial insects, the temperatures should be permanently above 12 ° C and it should not be too dry or extremely wet. The nematodes come in powder form and are dissolved in water and distributed on the lawn with the help of a watering can.

Eliminate grub damage

Have you discovered a population of white grubs in your garden and successfully combated it, or have the beetles finally hatched from their pupation and flown out? What remains is damage to the lawn, which weeds can now all too easily colonize. If there are only small holes in the area, a fast-germinating lawn pavement is ideal - the slower weeds don't stand a chance. If your entire lawn is affected, only sowing the lawn again with the right lawn seed mixture will help. We would be happy to help you choose the right type of lawn.

Conclusion: Fortunately, a strong infestation with white grubs rarely occurs in lawns. As a preventive measure, beneficial insects can be promoted in the garden. In addition, a moist, humus-rich soil favors the settlement of opponents such as the insect-infecting fungus Beauveria brongniartii and at the same time makes the location unattractive for the beetles to lay eggs.

If you would like to find out more about nematodes as beneficial insects, read on here.

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I study agricultural science with full conviction - an obvious choice for me, as I grew up on my parents' farm and learned early on to be caring for plants and animals.
Favorite fruits: grapes, mango and bananas
Favorite vegetables: Brussels sprouts, spinach and potatoes