Chafer grubs can pose a problem for those who prize perfect lawns, but can also be beneficial in your garden.
If you are wondering how to get rid of chafer grubs then it is likely that you have encountered a problem with your lawn. But it is important to realise that though they can lead to a lawn that looks less than ideal, there are many reasons want chafer grubs around. Only some chafer grubs pose a problem in a garden, and as you will discover in this article, not even these grubs need to considered a serious problem at all.
Read on to find out more about chafer grubs, when you might want to get rid of them, and why, most of the time in an organic garden, they are great garden wildlife to have around.
What are Chafer Grubs?
Chafer grubs are the grubs of chafer beetles. They live below the soil, beneath lawns, in beds and borders, and in compost heaps. There are a number of different species of chafer beetles present in UK gardens. These grubs can easily be confused with those of dung beetles and stag beetles, though these other creatures will do no harm in your garden and the stag beetle is an endangered species.
It is important to understand that there are around 20 different species of chafer beetles in the UK, and most of these will not do any harm in your garden.
The main grubs which pose a potential problem for gardeners are Smaller garden chafers (Phyllopertha horticola) and Welsh chafers (Hoplia philanthus). These types of chafer grub are most commonly found underneath areas of turf. They can be a viewed as a problem because they can destroy the root systems of grasses in a lawn – though they will not usually pose a threat to other mature plant species. Lawns can also be damaged by wildlife digging up the lawn to retrieve them.
Other species found in the UK include the cockchafer (Melolontha melolontha) and the summer chafer (Amphimallon solstitiale) will very occasionally feed on and damage the roots of plants in a bed or border, around the edges of a lawn. But these are usually not a problem in a garden.
All species of chafer, as you will discover below, have benefits within the garden ecosystem. One species – the Rose chafer grub (Cetonia aurata) can be particularly beneficial and is often found within a composting system, where they lend a helping hand in breaking down organic matter.
What Do Chafer Grubs Look Like?
Chafer grubs are chubby white grubs with bodies curved into a C shape. They have light brown heads and three pairs of legs close to the head end of their bodies. These grubs can reach a length of up to around 18mm long – bigger than the adults of the species. Larger chafer grubs such as the cockchafer and summer chafer can have larger larvae up to 30mm in length.
One thing to bear in mind is that it is very difficult to distinguish between the different grubs of different chafer species, and also difficult to distinguish those of chafer beetles from those of other beetles. Only if you are find these under turf, and see damage to the lawn, should you assume that these are feeding on the roots and that they may be a problem in your garden.
Chafer Grubs in a Lawn
As mentioned above, the only chafer grubs that can really pose an irritation to gardeners are small garden chafers and welsh chafers that can damage a lawn. If there is a serious infestation in a lawn, damage will be most clear between September and April, when the grubs are at their most active and are nearing maturity.
If chafers have been eating roots in a lawn, patches may become yellowed and die back. But a tell tale sign that chafer grubs are present are the disturbed areas of the lawn, where birds such as corvids (members of the crow family), foxes or badgers have dug to retrieve and eat them.
Gardeners who prize a perfect lawn may be irritated by the destruction, which can soon turn a neat and orderly area of turf into what looks like a pitted minefield. While other wildlife, such as leatherjackets, can also cause areas of lawn to die back, these will not usually be unearthed in the same way as chafer grubs by other animals.
In May or June, if you have a large infestation, you will see adult beetles flying up from the turf in large numbers, usually in the evening as light begins to fade.
In an organic garden, it is certainly worthwhile remembering that there are many more useful ways to use the space in your garden that will be far more beneficial to you (and to the ecology of the site) than a lawn. So if you are not able to maintain a perfect lawn, consider replacing it with a meadow garden, a vegetable plot, or even a beautiful and productive food forest. With more diverse and abundant, eco-friendly planting schemes, chafer grubs are far less likely to be a problem.
If you do wish to maintain a lawn, then keep it well watered and fed. (Though please make sure to use only organic fertilizers, and never synthetic fertilizers or herbicides, which pose a massive threat to the environment, wildlife and people). Problems are more likely to take hold in a lawn that is less heavily managed. Preventing moss growth may also help avoid a damaging population.
In very extreme cases, there is a biological control available. Gardeners can water in Heterohabditis bacteriophora nematodes any time when temperature are between 12 and 20 degrees C. (Usually July-September). These nematodes infect the larvae with a fatal bacterial disease. However, this is the ‘nuclear option’, and should only ever be viewed as a last resort.
Organic Control for Chafer Grubs
If the population of chafer grubs in a lawn has become excessive, this should be taken as a sign that the ecosystem is out of balance. In an organic garden, boosting biodiversity and maintaining a natural balance in the garden ecosystem is an important part of the puzzle. Excessive numbers of chafer grubs may be a sign that there are insufficient numbers of their natural predators in the ecosystem.
Attracting more rooks, crows, magpies, jays, foxes, badgers etc. to your garden is one of the best ways to keep their numbers under control. Make sure you have plenty of habitats and diverse planting to attract a wide range of wildlife into your garden.
The Benefits of Chafer Grubs in a Garden
The main reason why chafer grubs can be a good thing in your garden is that all species are important food sources for grub-eating wildlife. All organic gardens should have some ‘pests’, because it is only when these creatures are present that natural biodiversity will be maintained and their predators will be present too. So do not be too quick to wish to get rid of chafer grubs entirely.