What Are They?
Leatherjackets are the larvae of the European crane fly, commonly also know as Daddy Long Legs. These larvae feed on the roots of grass and consequently have a dramatic affect on the quality of the turf.
Have I Got Them?
Unfortunately when visual signs of Leatherjackets are evident most of the damage to the root system of the turf has already occurred. Crane fly hatch during August and immediately lay their eggs. It is approximately 2 weeks before the larvae hatch, when they immediately begin eating the roots of the turf. This means damage to the grass plant begins in September but at this stage the Leatherjackets are very small. However, they continue to feed through the winter and early spring growing in size until they stop eating in May and June.
One of the signs of significant numbers of Leatherjackets is the amount of starlings and crows pecking at the turf to access the grubs. One of the effects is that turf can be pulled away from the soil by hand because of damage to the root system.
How Do I Try To Control Them?
The most effective way to control Leatherjackets is to spray the turf with a proprietary product with the active ingredient Chlorpyrifos. Because the target is below the surface of the turf it is important that sufficient water is used. This will act as a drench rather than staying on the leaf; to help the active ingredient percolate into the turf it is helpful to apply when rain is expected.
Always ensure a suitable nozzle is fitted to the sprayer, a fine nozzle that is used when applying weedkiller will not achieve the drenching required.
How Do I Prevent Re-Occurrence?
The population of Leatherjackets is largely influenced by the weather so prevention is out of our control. The most important action to prevent turf damage is to spray before the end of November following the August when eggs are laid. This will successfully reduce the damage which otherwise would have been done throughout the winter.