Leatherjackets are the larvae of the European Crane Fly, commonly known as Daddy Long Legs. These larvae damage lawns by feeding on the roots of grass plants.
Adult crane flies emerge from pupae in late July and August, laying their eggs in the ground within 24 hours. The larvae hatch about two weeks later and start feeding on grassroots, continuing through winter and into spring. They stop feeding in May or June when they pupate in the soil. Generally, they stay underground during the day and move up to the turf leaves at night. Being very sensitive to drying, they cannot survive if exposed to the sun. On very cloudy days when the turf is wet, you can see the larvae in the turf. They are about 25mm long with grey/brown leathery skin.
Lawn damage occurs from autumn to spring, peaking in spring when the leatherjackets are fully grown. Symptoms include yellowing and weak grass areas where roots have been damaged. The grass can be easily pulled up with little or no root growth. Damage is usually more severe following a mild and wet autumn. Secondary damage may also be caused by birds and mammals digging up turf in search of leatherjackets.
How to Treat
The best time to control these insects is during their larval stage, not as flies. They can be controlled by hand removal or applying a biological nematode that attacks and kills the larvae within a few weeks. These nematodes are specific to the pest, making them safe for users, children, pets, wildlife, and the environment. The main application season is from late August to the end of October. A spring application is possible for severe infestations if the soil temperature is over 10 degrees Celsius.
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