Anyone seen the annual arrival of daddy long legs, or craneflies, in their house of late? They may be a minor irritant in the home, but when they lay their eggs in your grass that can be more of a problem.

This is because the larvae, known as leatherjackets because of their tough, leathery skin, feed underground on stems and roots, which can cause bare patches to appear in your lawn, or attract wildlife such as birds to peck at them, while badgers and moles will cause more lawn damage foraging for them.

There are around 350 species of cranefly in Britain.

Adults emerge and lay eggs on the turf from August to October which will hatch a few weeks later, which is when the grubs start to feed on the roots, going under the surface, says lawn expert David Hedges-Gower, author and chair of the Lawn Association.

A leatherjacket grub in the grassA leatherjacket grub in the grass (Image: Alamy/PA)

If it’s cold they will overwinter as small larvae and won’t do a lot of damage until mid-summer, but in a mild winter they will continue to feed and can become big enough to cause lawn problems.

Leatherjackets are often more prevalent after a wet autumn.

Badgers and moles sense movement in the ground and will dig away at your lawn to investigate.

How do you know if you have leatherjackets?

The easiest way to tell if you have an infestation is to find a grub. They have elongated tubular bodies and can grow up to 30mm, with no obvious head or legs and can be brown or black.

To encourage them out of the lawn, saturate the grass and cover it with black sacks or tarpaulin overnight.

In the morning, the grubs will have risen to the surface and will be easy to see. They can be discarded by picking them off by hand or leaving them exposed for hungry birds.

Is there anything gardeners can do to minimise the damage the grubs can do and deter predators from digging up the lawn?

1. Promote movement. Craneflies and their larvae don’t like movement or human noise or machinery sounds, so it might be worth running a mower at its highest setting over your lawn when possible, to deter them.

2. Get rid of thatch: They lay their eggs just below the surface, sometimes in the thatch. They like undisturbed ground, so places where there’s been no real effort made on the grass. Lawns with a lot of thatch are likely to have more.

3. Use different lawn seed: Rye grass doesn’t have many plants per square metre, so if you have an attack on a rye grass lawn that is already thinning out during winter – which it does – it doesn’t take much for a small leatherjacket infestation to wipe out a lawn, whereas in a traditional lawn, you’ll have 20,000 plants. So an infestation in a natural native lawn probably goes unnoticed.

4. Consider distractions: Birds, badgers, moles and other wildlife will forage for the grubs in your lawn, pecking and digging to extract the larvae. Try traditional bird deterrents like CD cases hanging on a line around the lawn, or netting, anything that would interfere with the insects re-laying eggs or stop creatures foraging.

5. Wait till spring to repair the lawn: If your lawn is thin it will be sticky and claggy and very cold, so you’ll never germinate anything. Clean up the mess as best you can and prepare for February to April time.