White grubs are white beetle larvae that live in the soil. The two main larvae that cause problems in the garden are chafer larvae and otiorhynchus larvae.
These soil worms can cause a lot of damage to shrubs, vegetable garden crops, but also very frequently to lawns.
However, be careful not to confuse these larvae with the larvae of spider mites, which are beneficial to soil life. These are often present in the compost. Do not hesitate to ask the advice of a specialist in biological control before launching a treatment.
Biological solutions to eradicate grubs
Regarding the larvae, they can easily be eradicated by a treatment based on HB nematode. This is an entomophagous micro-worm (which feeds on insects), which can be bought in the form of powder to be diluted in the watering of the plants. For the application, one can use a watering can or a sprayer dedicated to the application of nematodes (type aquanemix).
Regarding the Colorado beetle, it is possible to fight directly against them when they have reached the adult stage, using a Colorado beetle trap covered with nematodes.
The beetle will rub against the trap and will be contaminated by the entomophagous HB nematode. The simple presence of chickens in the garden is also an effective way to control the populations of these devastating larvae.
It is also possible to apply a mulch made of buckwheat hulls to limit the othiorynchus’ egg-laying in your garden.
All these means combined should allow you to limit the damage of these pests.