How to tell if leather jackets are a problem in your garden;
Lawns develop patches where the grasses turn white, straw-like and die, where the leatherjackets have attacked and fed on the grass root system. This can be distinguished from similar effects caused by lawn diseases or adverse growing conditions by lifting the affected turf and finding leatherjackets in the surface layers of the soil
Another method to reveal leatherjackets in lawns is to soak it with water and covering it with material impervious to light, such as sacking or black polythene. The following day large numbers of grubs should be found on the surface under the cover
Crows, magpies, rooks and starlings will search for leatherjackets in turf. These birds leave small round holes in the turf where they have inserted their beaks.
Leather jackets have elongate tubular bodies, up to 30mm long, and are greyish brown. They have no legs or obvious head.
A specific pathogenic nematode, Steinernema feltiae, can be watered into the turf or soil. The nematodes enter the bodies of leatherjackets and infect them with a bacterial disease. To be effective, the nematode requires soil that is well drained but moist and with a minimum temperature of 12°C (54°F). The turf around the edge of affected areas should be targeted to deal with larvae spreading out from infestation “hot spots” in the lawn. However, by the time areas of infestation become apparent, the soil may be too cold for nematodes to be effective.
As a preventive measure, apply nematodes in September to early October against leatherjackets. Nematodes should be applied as soon as possible after purchase, following the suppliers’ instructions for use. It may be necessary to water the lawn before and after application to ensure the soil is sufficiently moist for nematode activity and survival.
There are currently no chemical controls for leatherjackets on lawns which can be applied by amateur gardeners, however lawn care specialists such as ourselves are licensed to carry and apply insecticides which can be used to reduce and control Leatherjackets populations very effectively.