Chafer Grubs: what are they and how do they spread?
In May- June your lawn is at risk from a destructive pest which on its own can damage turf roots, but in addition can attract predators attempting to dig for them.
Chafer Grubs can decimate lawns in a few months, and their arrival in your garden can be hard to stop. The damage might not become visible until Autumn, however the process of egg laying begins in early June, with the grubs reaching full growth (and full appetite) over the remainder of the summer.
There is no pesticide that can stop Chafer grubs- though you can use biological nematodes to limit their spread. The key is to recognise the signs of Chafer grub damage & introduce the nematodes into the soil while the weather is still warm enough. Equally important to maintaining a grub-free lawn is prevention- regular maintenance, careful attention to inconsistencies like moss. The grubs will at present be getting nearer the surface, having dug themselves deeper in the spring to reproduce. Now they’re returning to the surface- and bringing an appetite. They feed primarily on roots, but the real source of Chafer annoyance is the local wildlife which will arrive to feed on them. Badgers, foxes and crows can pick turf apart to try and reach the grubs- causing very serious damage. These can be localised and extremely destructive- sometimes requiring total replacement of the turf. Lesser damage can require seeds to be sown over the affected areas. Unfortunately it can sometimes be difficult to identify the cause of your lawn’s damage, especially as Chafer grubs share many of the same destructive tendencies as Leatherjackets- different species grub, much larger but less popular with the local mammals (although crows and magpies love rooting for them). Simulating night- ie pouring water over the lawn and covering it with a light-excluding sheeting (such as polythene) and leaving overnight- with the sheeting removed a large number of brown-grey grubs will be visible. By comparison, Chafer grubs are white, and less inclined to head to the surface overnight. If all else fails it’s possible to find the irritating creatures by digging down into the layers where they secrete themselves.