Leatherjackets cause damage to the lawn by feeding on the roots of the grass. Further damage which is often more serious than caused by the leatherjackets is caused predators feeding on the grubs as they tear up the turf. These predators include birds like crows and rooks and other mammals such as foxes and badgers.
Lifecycle of Leatherjackets
The cycle begins when the Crane Fly lays their eggs, (up to 300) in the lawn during the late autumn. The eggs hatch after two weeks into Leatherjackets. The Leatherjackets remain in the ground over winter as they grow and feed on the grass roots.They continue feeding and growing into following spring is when the most damage is caused. During May and June they pupate before they hatch into Crane Flies, where they surface and fly away. The Crane Flies then mate and the process begins again as they lay their eggs in the autumn.
Prevention of Leatherjackets
In the case of Leatherjackets, prevention is certainly better than the cure for the amateur gardener or lawn care enthusiast. If you observe a large population of Crane Flies during the later summer / early autumn period this can be an early indicator that Leatherjackets are likely to be a problem.The damage the following spring is often more severe if the autumn - winter period has been particulary wet and mild. If the infestation is severe the grass will have a yellowing apearance and can easily be pulled out by hand causes by the grubs eating the roots. Bird damage is a good indicator of a large population of Leatherjackets as they tear up the turf as they go insearch of the grubs.
If this is the case there are numerous nematode products that can be applied to control the Leatherjackets. These nematode products should be applied during the late summer - early autumn when the ground is still relatively warm. A further application in the spring can be made if the infestation is severe. However it is important to note that these products require a warm soil to be effective and this is not always the case in the spring time.
Nematodes are microscopic organisms that kill the Leatherjackets but are harmless. However it is important that you adhere to the manufacturers guidelines when applying these products.
Another method of removing Leatherjackets is to place a black polythene sheet over the lawn during the night.
The following morning the Leatherjackets will come to the surface of the lawn where they can be removed. This method of control is significantly more effective following rainfall when the soil is very wet.