Leatherjackets, the larvae of craneflies, might seem harmless when seen in your house, but when they lay eggs in your lawn, it can create a major problem. These grubs, with tough, leathery skin, feed underground on grass stems and roots, leading to bare patches in the lawn. The damaged areas can attract birds looking to peck at the grubs, while badgers and moles may also cause further destruction while digging for them.
In the UK, there are around 350 species of craneflies. The adults emerge and lay eggs on turf from August to October, which eventually hatch into grubs that start feeding on roots underground. This feeding activity usually becomes noticeable between November and January or February, resulting in grass dying off or being pecked at by birds.
Leatherjackets are more abundant after a wet autumn as moist conditions support the survival of eggs and larvae. Badgers and moles can detect the movement caused by the grubs in the ground and may dig up lawns in search of them.
To check for a leatherjacket infestation, look for elongated grubs that can grow up to 30mm long, with no distinct head or legs. An effective way to bring them to the surface is by saturating the grass and covering it with black sacks or tarpaulin overnight, allowing the grubs to emerge and be removed by hand or eaten by birds.
Gardeners can take several steps to reduce the damage caused by leatherjackets and discourage predators from disturbing the lawn. Firstly, creating movement in the garden by running a mower over the lawn can deter craneflies and their larvae. Additionally, removing thatch, opting for different lawn seed varieties like bent and fescue grass, and using nematodes – microscopic worms that target pests – can help control leatherjacket populations.
Furthermore, distractions like bird deterrents and repairing the lawn in spring can also mitigate the impact of leatherjackets on your lawn. By taking proactive measures and staying vigilant, gardeners can protect their grass from the threats posed by these troublesome grubs.