Now I know that looks aren’t everything BUT these really are grim to look at and they can do a lot of damage too. Chafer grubs are the young or larvae of garden chafer beetles (those brownish beetles which suddenly appear in large numbers in May and June and clatter against the windows !). They are one of the common causes of yellow patches on lawns (take a look at Jack’s article about leatherjackets to find out more about the other main cause at this time of year, leatherjackets). These plump, white-bodied brown headed grubs are even more attractive to badgers, foxes, magpies, so the damage to the lawn is even more severe. There are other species of chafer grub which nibble vegetable and ornamental plant roots and can cause severe damage.
Chafer grubs will feed on the roots of your grass until late into autumn then, as temperatures drop they burrow deeper into the soil and pupate. They stay snug in the earth until spring when they hatch out into adult beetles in May and June and then begin to lay eggs, starting the cycle of damage all over again.
Like with leatherjackets, the best method of control is to treat with nematodes, there is one especially formulated for use against chafer grubs. This one is called Heterorhabditis bacteriophora, a microscopic worm-like creature which you buy several million at a time and which swims through the moist soil, seeking out the chafer grubs, entering their bodies and destroying them. Once they have killed one they move off to kill another. It is a clever use of a natural enemy of an awful pest and works brilliantly, particularly if the grubs are still quite young and provided the soil is moist (you may need to water the lawn if weather conditions are dry) and at 12C or above, so treatment is best done ASAP. The great thing about this is that not only does it work well but it is also totally human-, pet- and wildlife-friendly. You can find out more or order it from my website www.pippagreenwood.com/products/protect-your-crops