Chafer grubs are the larvae of chafer beetles in the family Scarabaeidae, which also includes dung beetles. There are eight species of chafer beetle in the UK. Some can cause issues in lawns, but many do not. In fact, some chafer beetles are pollinators, while some larvae help break down decaying matter. What’s more, chafer beetles and their larvae form part of healthy ecosystems, providing food for a range of birds and mammals.
How to identify chafer grubs
The large, c-shaped fleshy chafer grubs found in lawns can grow to nearly 2cm long. They have brown heads and creamy bodies with three pairs of legs. They could be confused with vine weevil larvae or leatherjackets (cranefly larvae). However, vine weevil grubs are much smaller and don’t have legs. Leatherjackets are large, but they’re darker and have no clearly identifiable head and no legs. Stag beetle larvae also resemble chafer grubs, but they grow much bigger and are almost always found in rotting tree stumps or roots. Stag beetle larvae are harmless, important in recycling dead wood, and – like chafer grubs – a valuable part of the food chain.
Where do you find chafer grubs?
Different species of chafer grubs can be found in lawns, borders and compost heaps. Garden chafer and Welsh chafer grubs (not restricted to Wales) are the most likely to cause problems in lawns. Cockchafer and summer chafer grubs also live in soil and can be found in garden borders. Although they occasionally cause issues by eating the roots of plants, in most cases they cause little or no harm, so can be left alone.
If you’re lucky, you might have rose chafer larvae living in your compost heap, helping with the composting process. They live in decaying vegetation for two years before pupating in the summer. Most emerge as adult beetles the following spring. The iridescent emerald green adults can be seen flying around in the late spring and summer, feeding on pollen, nectar and petals from a range of flowers including roses, honeysuckle and elder.
How to get rid of chafer grubs
Unless they’re causing serious problems in lawns, leave the grubs to provide food for mammals and birds such as starlings, which are now on the UK Red List due to widespread declines in populations since the 1990s. In some areas of the UK, chafer beetle larvae also provide an important source of food for chicks of the wheatear – an amber-listed summer visitor.
If chafer grubs are causing serious problems, you can repair the lawn by sowing seed or laying turf. They can also be treated with nematodes (usually Heterohabditis bacteriophora) that kill the grubs. However, once it has become obvious there’s an issue with chafer grubs, it can sometimes be too late to apply nematodes, as they require warm soil temperatures (12-20°C) to work. There are no pesticides licensed for use by home gardeners on chafer grubs.
Frequently asked questions
How do I know if my lawn has chafer grubs?
If you have chafer grubs in your lawn, you might see starlings or rooks feeding, or large bare patches where badgers or moles have been digging. You may see yellowish patches and when you dig under the turf, there may be grubs visible. While leatherjackets may cause some damage to grass roots, they do not usually attract animals that will dig up patches of lawn.
What damage do chafer grubs do?
Chafer grubs in borders are unlikely to do much damage. When grubs in the lawn are nearly fully grown in early autumn, or when they move back up through the soil after winter hibernation and before pupating in spring, they may damage grass roots and encourage birds and mammals to dig up lawns. You might notice yellow patches in the lawn and areas of churned up grass where animals such as badgers have been searching for the grubs.
