Biological pest control

Our gardens can be devastated by chafer grubs, leatherjackets, slugs and vine weevil larvae. Steve and Val Bradley look at a natural solution in the form of nematodes

- Steve and Val Bradley

GROWING plants has always been a balancing act between the gardener and the pest population. Some insects are welcome pollinators, while others like ladybirds are natural predators that help control damaging pests such as greenfly. Some, like aphids, are obvious, while others do their damage unseen until it’s too late.

Danger to plant roots

Chafer grubs and leatherjackets are both larval stages of insects and rely on eating plant roots for their development. Unfortunately for us, this includes our lawns. Vine weevil larvae are similar, but less fussy. They will munch their way through most young roots and the first you know about it is often when the plant collapses.

Nature needs a hand

The go-to method of control used to be chemical, but thinking has changed and there is now more emphasis on letting nature control itself. However, there are times when this is not happening or you need it done more quickly because the plant is under threat. Some of the most common (and destructive) garden pests have increased in numbers thanks to a lack of intervention by well-meaning gardeners.

Slugs and vine weevils regularly feature in the RHS Top 10 pests, because dealing with them has become a contentious issue and the old slug controls are being withdrawn, quite rightly, for environmental safety reasons.

Grass can really suffer

Grass pests, including chafer grubs and leatherjackets, have become a major problem, killing large areas of turf as they develop into adults. The problem gets worse when birds, badgers and foxes, which see the larvae as juicy morsels, rip up the lawn to get at their prey, causing damage.