As the temperature rises with the arrival of spring, magpies, crows, badgers and foxes will start their hunt for some of their favourite snacks – chafer grubs, also known as lawn grubs. These are the larvae of beetles, such as chafer beetles, as well as the larvae of crane flies (known as leatherjackets). The larvae live just below the surface of the lawn and the animals and birds will scrape and dig in search of them, destroying the lawn in the process.
But it's not just the larger prey that can cause damage – the grubs do their fair share of harm themselves, too. They can attack the grass roots, which leads to slow growth and yellow patches on your lawn.
If you've been busy perfecting your lawn care, then seeing your hard work destroyed thanks to pesky grubs can be devastating. But don't worry – we've brought together all the expert advice you need to keep these pests at bay.
Article continues belowHow to get rid of chafer grubs using beneficial nematodes
When it comes to chafer grubs, the go-to approach to tackle these intruders tends to be with beneficial nematodes, available on Amazon. These are microscopic, living organisms that infect the grubs with a deadly bacterial disease.
Nematodes occur naturally in soil, and some companies, such as BASF, breed specific types that each seek out and kill particular prey. Their dedicated products arrive in the form of a fibrous paste, which you then disperse in water (following mixing guidelines). "The watery mix can then be applied via a watering can with a coarse rose for a small lawn or with a hose-end feeder for larger lawns," the team at BASF explains. Be sure to follow the instructions on your chosen product's label, though, as application methods may vary.
"Once the garden chafer grub and leatherjacket population has been reduced by the nematodes, the large amount of nematodes applied will die back to their original numbers found naturally in the soil," explains BASF.
This treatment tends to be quick and effective. "Normally, two treatments are sufficient to exterminate a colony," says John Negus, a renowned gardening expert and author of Garden Tools, An Illustrated Guide to Choosing, Using and Maintaining, available on Amazon.
And once you've dealt with the pests, repair damage either by laying new turf or sowing grass seed in mid to late spring. This is when any leftover grubs move deeper into the soil to pupate.
"Poorly maintained lawns are more susceptible to damage, so attention paid to lawn care can help avoid infestations," John adds.
Shop for nematodes to get rid of chafer grubs
Nematodes are ideal is you're looking for a natural and non-chemical way to tackle lawn grubs. But, there are alternative options available, too. Here are three well-rated products.
A water-dispersible powder that’s easy to mix by adding it to water. Using a watering can, it can then be applied to the lawn and will cover an area of around 10 square metres.
Natural product that is safe for children, pets and wildlife, and the lawn can be used immediately after application. Covers 100 square metres or 50 square metres when used at double strength, typically in spring.
With an average 4 out of 5 rating on Amazon, this natural product will treat up to 100 square metres of lawn. As it's a perishable item, it has around a two-week expiry and will need to be stored in a fridge until use.
When is the best time to get rid of chafer grubs?
As well as knowing how to get rid of chafer grubs naturally, for the biggest chance of success, you'll also need to know the best time of year to take action.
"The critical times for controlling this pest are April and September," says John Negus. This is partly because, for the nematodes to be effective, they need to be applied when the soil is warm and moist (between 12–20ºC, as the RHS advises). But also, at this time, the grubs will be nearest the surface of the turf and thus feeding on the roots.
Add it to your list of other spring and autumn lawn care jobs and you'll be rewarded with a healthy stretch of green.
You can also add nematodes as a preventive measure from July to September, the RHS says.
And if you're specifically looking to get rid of leatherjackets, a good rule of thumb is to wait two weeks from when you first see crane flies (usually in spring) before applying nematodes. Then, apply again in two weeks' time, keeping the soil moist throughout, says BASF.
How do you know if you have chafer grubs in your garden?
As John Negus says, the damage from lawn grubs can usually be spotted in spring or autumn.
Watch out for patchy areas of lawn turning yellow and dying, and more birds being attracted to it than usual in their hunt for the larvae.
In terms of the grubs themselves, beetle grubs, such as chafer grubs, have stout white bodies curved in a 'C' shape, light brown heads, and three pairs of legs at the head end, says John. Many kinds can be up to 18mm long.
And as for leatherjackets? BASF explains: "Leatherjackets are about 25mm long, brown, legless and with no distinct head."
The original version of this article previously appeared on Gardeningetc, a sister website to Homebuilding & Renovating.
