The adult crane fly looks like a large mosquito with long legs. They don’t bite or sting and are harmless to humans and pets. The larvae are small, gray-brown wormlike grubs; they develop tough, dark skin and are often called leatherjackets. Adult crane flies emerge from the soil between mid-August and mid-September. The females mate and lay eggs in the grass within 24 hours. Then the adults die without damaging the grass. In autumn and during warm winters and spring until mid-May, the crane fly eggs hatch, and the larvae feed on grassroots and crowns. This is the time when larvae do the most damage. During July and August, larvae burrow just below the soil surface, stop eating and go dormant. They then become adults, and the cycle begins again.

Everyone should make it a practice to inspect and spray for crane flies. They can destroy a lawn in days or weeks. They are in the air so they may choose your lawn for their nesting spot. Maintaining proper irrigation, fertilization, and turf health helps the grass outgrow crane fly damage.

Diazinon is a widely used pesticide to keep crane flies and other insects under control. It is important that it be applied once in the fall and once in early spring in order to treat the pest in its most harmful stages.