Recognize, combat and prevent grubs

Grubs are larvae of various species of leaf beetles. In the Netherlands, the cockchafer, June beetle, rose beetle and Salland beetle are the most common.

Grubs live in the ground and you will therefore not easily observe them. You can see the beetle flying, especially in the spring.

Grubs live in the ground and are therefore sometimes difficult to find. If you are unsure whether there are grubs in your lawn, you can carefully shovel away a piece of grass from an infested area of ​​lawn to check whether grubs are visible. Identifying grubs in your lawn can help prevent further damage and take timely action.

When you dig them up and hold them in your hand, they curl up into a typical “C” shape. The grubs can grow up to four centimeters in size and are completely beige in color, except for the head. The head is colored chestnut brown. Just below the head you can clearly distinguish six legs. This is also the characteristic to distinguish the grub from the leatherjacket (larva of a crane fly).

The life cycle of grubs begins with adult cockchafers and other beetles flying around from late April through June, looking for suitable places to lay their eggs. These eggs hatch after several days to weeks, usually about four to eight weeks after the adult beetles have been observed. The larvae then continue to develop until they are large enough to pupate and fledge as adult beetles, which then lay eggs. In the Netherlands it usually takes three years for the life cycle to complete.

Bare and yellow patches of lawn
When grubs feed en masse on the roots of grass, the best available type of food, the grass above the ground dies. Without roots, the grass plants cannot survive and their health will visibly decline above the ground. Unfortunately, this can be seen in yellow or bare spots in the lawn. You can easily lift these areas of yellow and dead grass because the roots are missing. Roots of other garden plants can also attack the grubs.

Birds and moles
In addition to the feeding damage of the grubs, their natural enemies, such as birds and moles, can also cause damage. Nothing will stop these animals from getting the tasty snack out of the ground, especially not a beautiful lawn. As a result, you often see areas of disturbed grass where these animals have gone in search of grubs.

You can combat grubs easily and effectively with Phora nematodes.

The most effective nematodes against grubs are Phora, which are active from 12 degrees, but are most effective at temperatures above 18 degrees. Phora penetrates the grubs and kills them within a few days using a bacterium that this nematode always carries.

The best way to combat grubs is when they are smaller than two centimeters. That is about four to eight weeks after the adult beetles have been seen. This is usually from June to September. If you have not seen any beetles flying, it is best to combat them in August or September.

Even in the spring, between April and the end of May, last year's larvae can still be controlled. What is important for the timing of control is the soil temperature, so do not control too early, but certainly not too late in the year.

Because grubs live for several years as larvae, they must be controlled every year. This way you fight the young grubs before they can grow up. If you experience a lot of inconvenience, we recommend 2 to 3 treatments per year with at least a month in between.
Our biologists monitor the development progress of these grubs, so we know when the best time to combat them comes. Keep an eye on our newsletter to be informed of these moments.

If you have not seen any beetles and want to prevent this pest, it is best to apply Phora nematodes in August or September.

Combat grubs with garlic
You could keep grubs and leatherjackets away because of the strong smell of garlic extracts. However, this is not pleasant air for you either! It is claimed that the growth of grubs is stunted by garlic, although no scientific evidence has been found for this.

The garlic does not ensure that the grubs are controlled or disappear.

Control grubs chemically
You can choose to combat grubs chemically. However, we strongly advise against this because it not only affects the grubs, but also the entire soil life. These substances usually act on the nervous system of insects and do not distinguish between different species. This seriously affects all soil life, which then affects plant health and your beautiful lawn. Based on our mission and vision, we therefore always recommend using an ecological method of pest control.