What are Leatherjackets and what do they do?
Leatherjackets are the larvae of the crane fly (daddy long legs). In small populations, you are unlikely to notice any activity in your lawn. In larger populations they become problematic quickly.
Leatherjackets cause damage to lawns by feeding (often unnoticed) on the root structure of the grass itself. The problem is usually only detected when the population of the grubs in the soil is too large for the lawn to cope with, resulting in areas of lawn dying off. Often worse is the secondary damage which can follow – these grubs are the prey of birds, badgers and foxes. With a lack of rooting turf will often pull apart easily to reveal leatherjackets feeding in the root zone.
When will I see Crane Fly and Leatherjacket activity?
Some leatherjackets hatch into crane-fly in spring, however most emerge from the ground during late-summer/early autumn. Shortly after the crane-fly hatch they will mate, then return to your lawn to lay their eggs. A single female crane-fly is capable of laying up to 300 eggs, that’s a lot of grubs!! A couple of weeks later the small grey-black leatherjackets will hatch and begin feeding on the roots of your lawn.
You may notice leatherjacket damage occurring when patches of your lawn begin to turf yellow and die off. As there will be very little root left, the grass will easily pull up to expose the soil and grubs beneath.
How can I stop Leatherjacket damage?
With no pesticides available for the control of leatherjackets, the only product on the market is the biological control using nematodes. Nematodes are microscopic organisms when, if used correctly, can be applied to the soil to seek out the chafer grubs to attack them. There is a limited period of use for nematodes which can been seen on the Pitchcare.com chart below.
Another organic method of control is what we call ‘sheeting’. After heavy rain or having thoroughly watered any yellow patches in the lawn, cover them with black plastic sacks or tarpaulin and leave overnight. When you remove the covering the following morning, the leatherjackets will have come to the surface and can be removed by brushing, picking or blowing them off. If you’re lucky, you might get a helping hand from some garden birds.