What are Chafer Grubs?
Chafer Grubs are the larvae of the common summer Chafer Beetle and they feed on the roots of your plants and decaying plant material.
These Beetle Grubs hatch from May – June and likely to cause havoc to your garden lawn, hence why they are sometimes called the ‘May Bug Larvae’. In most instances, the damage they do is minimal, however if these lawn grubs build into hoards then significant areas of your lawn can suffer from damage and drying due to a lack of water and nutrients.
Further damage can be done as common predators such as magpies, foxes, badgers and starlings tear up your lawn to find these protein rich critters lying a few inches below the surface.
Species of Chafer Grubs
There are 4 common garden chafer grubs in the United Kingdom, including: Garden Chafer, Welsh Chafer, Rose Chafer and Cockchafer grub. The main problems of chafer grubs in lawns is likely to be caused by the Garden Chafer bug and the Welsh Chafer bug.
What damage can lawn grubs do?
You will notice Chafer Grubs in your lawn around autumn and spring time if you are a victim to their attack. This is the part of their lifecycle where they mature and consume the grass roots from your garden lawn.
To spot damage, look out for any yellow patches on your lawn during these months, or any discoloured spots that may have been caused by those predators we mentioned earlier trying to eat the lawn grubs.
What damage to Chafer Grubs to do garden borders?
These white grubs can also affect vegetable beds and garden borders, they can kill early vegetables, strawberries and bedding plants. They can sometimes eat into your potatoes or bulbs, so watch out. Overall, border damage by grubs is rarely significant so don’t worry too much.
Garden Grubs Identification in the UK
If you are feeling brave, you can look for them under the loose turf where the patches appear on your lawn - they are white grubs in the soil. See if the grass comes away easily by tugging gently, if it does, it’s a high chance these white grubs are under the surface of the soil.
We recommend you use a suitable instrument such as a pruning knife to slice out a section of the turf to inspect any areas that wildlife may be giving their attention to, just in case they are causing the problem too.
The grubs have white bodies with brown heads and 3 pairs of legs close to their head. You can recognise them as ‘C’ shaped and can measure 25mm in length. Further in their lifecycle, these will develop into summer chafer beetles which measure 2cm in length and buzz around your garden in the early evenings in the UK.
Chafer Grub Treatment
We suggest before you consider refurbishing and mending any damage to your garden lawn caused by grubs, that you kill the larvae using chafer grub killer. These little white Chafer grubs can live in the soil for three years and these can multiply dramatically in this time frame before turning into summer chafers.
Chafer Grub Nematodes
In terms of controlling them, you can use biological control such as chafer grub nematodes once you have confirmed the damage is caused by grubs. You can use Nemasys Chafer Grub Killer which are microscopic animals that combat the larvae by infecting them with a deadly disease when they are watered into your lawn. Ensure that your ground is humid and at a soil temperature range of between 12-20 degrees Celsius.
You could also consider using horticultural garden fleece as a barrier to keep adult garden chafer beetles away from your vulnerable plants.
There is currently no approved chemical treatment for chafer grubs in your garden lawn for gardeners.
How do I prevent chafer grub attacks in the future?
In order to prevent chafer grub attacks in the future we suggest that you frequently check for signs of chafer grub infestation as outlined earlier in the article and deal with it proactively.
It is definitely worth scarifying and aerating your garden lawn during the autumn months. If your lawn has a reputation of infestation or disease try to wrap the turf by rolling it deep during the spring months.