Leatherjackets in Lawns

Leatherjackets are the pupal stage of the Crane Fly or Daddy Long Legs

You may have seen a number of small grey grubs in your lawn when you mow or trim the edges – these are most likely the larvae of Crane Flies, known as ‘Leatherjackets’.

These grubs are laid by adult Daddy Long Legs towards the end of the summer and into early autumn, growing into bothersome grubs within a few weeks. The grubs feed on the roots of grasses and small plants, including seedlings.

The grubs survive over the winter by sheltering beneath the soil, with mild winters resulting in particularly large and damaging larvae which chew away at your lawn and leave yellow patches. These will then pupate into adult Crane Flies in the summer, which you can often find in vast quantities on your lawn surface and around lights in the early evening.

Treatment

There is currently no chemical treatment available for Leatherjackets, as the Bayer Lawn Grub Killer was withdrawn in 2013.

One suggestion for a nature friendly approach is to moisten the lawn, then drape an opaque dark fabric or plastic over the area. This encourages the grubs to rise to the surface so they can then be exposed the following day in massive quantities, ready for your local birds to gobble them up! Be prepared for a feeding frenzy!

We do supply a biological control for Leatherjackets, made by Agralan. This comprises a direct delivery of Parasitic nematodes called ‘Steinernema feltiae’, which are a natural predator of the Leatherjacket. The supplied package is mixed in a watering can and applied to the whole lawn in September/October with a repeat treatment in March/April if necessary. Note: as these are living creatures, they must be applied as soon as they arrive and soil must be at least 10ºc.

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