In the wild: Mainly grass roots, sometimes small plants and seedlings
Throughout UK and Europe
Adult crane flies or (daddy longlegs) emerge during late summer to mate and lay their eggs into lawns and flower beds. They are greyish-brown long-legged flies that are around 4cm in length and have a wingspan of up to 6cm. Their larvae, commonly known as leatherjackets, develop underground over 8-10 months where they feed on grass and plant roots. The larvae are greyish-brown, have tubular bodies and grow up to 3cm in length. When fully grown, they pupate just below the ground and then emerge as adults in late summer to early autumn.
Adult crane flies do not cause any damage. On lawns, their larvae cause patches of dead and dying grass as they feed on the grass roots. Young plants and seedlings are often killed by the feeding of crane fly larvae on the roots.
Commercially available entomopathogenic nematodes can be used as a precautionary treatment where crane fly may occur. These microscopic worms are watered into the lawn or flower beds where they search for crane fly larvae, enter inside them and cause a bacterial infection within which kills them.
Entomopathogenic nematodes can also be used as a crane fly control treatment. In addition, crane fly larvae are very susceptible to drowning, so a thorough and prolonged watering of a lawn should significantly reduce their numbers.
Crane fly larvae are a good food source for birds such as crows, magpies and starlings. Regularly mowing an infested lawn will enable these birds to find the larvae more easily.