Leatherjackets

In the last couple of years leatherjackets have proved to be a huge problem in the lawns of Donegal. While spotting an infestation of leatherjackets is notoriously difficult, autumn is an ideal time to try and identify and treat these little pests before the problem gets out of hand.
   Leatherjackets are a real nuisance in the garden. They are the immature larvae of the common Daddy Longlegs. They take the form of two inch long, grey, legless grubs which have particularly tough skin. These grubs favor reasonably loose soil and are commonly found in gardens which have been cultivated in the last few years. They live underground where they eat the roots of plants, leaving yellow or brown patches of dead grass on lawns. In particularly bad cases whole lawns have been killed off by an infestation. In the late summer these grubs form into daddy long legs which quickly lay their eggs back into infected lawns. These eggs hatch in about two weeks and the grubs immediately start to feed on grass roots, on which they will continue to feed right through the winter into early spring. A wet autumn like we are having this year will also help to increase the number of leatherjackets as damp conditions increases the survival rate of eggs and young grubs.
   Spotting leatherjackets in a lawn can prove tricky. By their nature these grubs feed from below the ground, so the damage to plants and grass can be done before the problem is spotted. In the last few weeks however you may have noticed large numbers of mature daddy long legs emerging from your lawn in the early morning or as the lawn was being mowed. This is usually the first sign of trouble as they will have been laying their eggs in the lawn. Wet weather can also give these pests away, as following a heavy night of rain leatherjackets can often be found gathering on the surface of the lawn or on the nearby driveway.
   When an infestation of leatherjackets is discovered there are a number of ways of solving the problem. The most common and effective way of dealing with an infestation is to treat the area with a suitable soil insecticide. These insecticides are available from most garden centres and should be applied according to the manufacturer’s instructions in the autumn when the grubs are active and before they have done too much damage.
   However if you don’t like using chemicals an alternative is available. An old gardener’s trick is to water the effected area thoroughly in the evening and covered with black plastic sheeting. In the morning the grubs will have been drawn to the surface where they can be physically removed and disposed of or left for the birds to eat.
© Copyright, Highland Landscapes, Letterkenny, 2008.