Collection: Control chafer grubs

What is a grub?
A chafer grub is the larva of a scarab beetle. The most common are the June beetle, May beetle, and garden foliage beetle. The grubs have a similar outward appearance, but can differ in size.

What damage do grubs cause?
The chafer grubs cause considerable damage to plants as they feast on the roots. Between July and September, damage can be so great that large parts of a lawn can turn yellow and die off.

In addition, there is a risk of secondary damage from birds, moles, and other animals who feast on the chafer grubs. They can dig up the entire lawn and cause major damage in their search for the chafer grubs.

The lifecycle of grubs
There are different types of beetle, each with its own lifecycle, which can vary from one to four years. Most beetles lay their eggs between May and July, and it then takes three to six weeks for the young grubs to hatch. The chafer grubs will grow increasingly large in the first to third years until they pupate into an adult beetle. 

Managing grubs with nematodes
Chafer grubs can be tackled with nematodes most effectively while they are still young (smaller than 2 cm), in which case you will usually find between 80% and 95% dead within a few weeks of treatment. If the chafer grubs are larger, the efficacy of nematode treatment can fall to below 50%. It’s therefore important to apply the nematodes at the right point in time, when the grubs are still small. It’s also important to give them plenty of water, as this will help the nematodes to penetrate the soil and reach the grubs. In addition, nematodes will die if conditions are too dry.

As many chafer grubs live for several years, they must be treated every year so that the younger chafer grubs are dealt with before they become larger. If you have a stubborn infestation, you should apply nematodes two to three times a year, with a few months in between treatments.

What is the best time to treat chafer grubs?
The best time to treat chafer grubs is two to three months after the beetles emerge from the ground, which is between June and September. If you don't spot the beetles, we recommend applying the nematodes in August and September. The younger/smaller the chafer grubs, the more effective the treatment.

Which nematodes should I opt for?
Heterorhabditis bacteriophora is by far the most effective nematode for chafer grubs, so we recommend using it. These nematodes cannot tolerate cold and work best at soil temperatures in excess of 18°C. If the soil temperature is likely to fall below 12°C, they will be less effective. This is typically the case at the end of September or beginning of October, so don't delay when it comes to using the nematodes!