Damage to lawns occurs from autumn to spring but is most severe in
the spring when the leather jackets are fully grown.
appear as yellowing, weak areas of grass where the roots have been
damaged. The grass can be easily pulled up with little or no root
growth. Damage is usually more severe when the previous autumn has
been mild and wet. Secondary damage can also be caused by birds and
mammals digging up turf in their search for Leatherjackets.
Adult Crane flies hatch from pupae in late July and August and lay
their eggs in the ground within 24 hours of hatching. The larvae
hatch about 2 weeks later and start to feed on grass roots, which
continues through winter and into spring. They stop feeding in
May/June when they will pupate in the soil. In general, they stay
underground in the day and move up to the turf leaves at night.
They are very sensitive to drying and do not survive if they are
dried out by the sun. On very cloudy days when the turf is wet you
can see the larvae in the turf. They are about 25mm long and have a
grey/brown leathery skin.