Lawncare tips – Leatherjackets

Lawncare tips – Leatherjackets – Why is my lawn going bald?

These could be the culprits….Leatherjackets are unattractive little creatures that can cause damage to your lawn.

Leatherjackets are the larvae stage of crane flies (or daddy-longlegs as they often known). Whilst a daddy-longlegs can be irritating enough flying aimlessly around a light fitting on a late summer’s evening, the damage their offspring do to lawns and turf can be far more vexing.

Life cycle of a daddy longlegs

Unbeknown to many, most of a crane fly’s life is spent underground. They hatch in September and October and spend all their time underground. In late May and June, the larvae pupate. This is the beginning of the process of becoming the insects we see flying around. Once this transformation is complete, they only live around two weeks during which time the crane fly’s main aim is to mate and lay more eggs in grass.

Lawncare tips – Leatherjackets – How does the daddy longlegs cause problems for turf growers and lawn lovers?

The problem with this whole process for turf growers and those of us with lawns is that in the months between hatching and pupating, the main activity of the larvae is eating grass roots. This doesn’t do the plants any good and, if the numbers of leatherjackets are significant enough, will result in areas of dead, brown turf.

Lawncare tips – Signs of leatherjacket damage

Of course, some turfgrass diseases can result in similar looking symptoms but it’s fairly easy to see whether leatherjackets are the cause:

Some birds, particularly, crows and magpies, enjoy dining on the leatherjackets, you may notice more such birds on the turf. The ground may also be marked with small holes where they have plunged their beaks into the soil to retrieve the grubs.

Look at the top layers of soil, particularly at the edges of the dead areas, where you will probably come across the leatherjackets. They are up to 3cm long with large, round, grey/brown bodies, they’re fairly distinctive.

Lawncare tips – Treatment for leatherjackets

Above all else, leatherjackets are particularly devastating for turf because they’re so difficult to control. The only home treatments for leatherjackets are nematodes which are watered into the soil. Unfortunately, these are only effective if the soil is warm enough. In the UK at least, such temperatures rarely coincide with the times of year in which leatherjackets are active.

This year could see leatherjackets become more of a problem for turf growers and gardeners. After wet autumns/winters, numbers of leatherjackets are particularly high since these are the ideal conditions for the crane fly eggs to hatch.

Worse, at the end of this month, changes to regulations will mean that the last chemical treatment effective against leatherjackets will no longer be available.

All is not lost, however. Though difficult to eradicate one can still use nematodes to keep leatherjacket numbers low. Apply them while temperatures are still high enough in early autumn as the larvae hatch.