Leather Jacket or European Crane Fly
The adult European crane fly has very long legs and looks like a large mosquito with a body about one inch long, not including the legs. Homeowners are alarmed when thousands of these large flies gather on the sides of homes. The crane fly does not bite or sting.
The larvae is a maggot called a Leatherjacket, and is light gray to grayish, greenish brown, with irregular black specks of various sizes. The head is small and the anal area has six tapering lobes, giving it a unique appearance that makes it easy to identify.
Adult crane flies emerge from soil of lawns, pastures, and other grass areas from late August to mid-September. The females mate and lay eggs in the grass within 24 hours after emerging. These eggs hatch into small, gray-brown, wormlike larvae, which develop a tough skin; they are commonly called "leatherjackets." The leatherjackets feed on the root crowns of the grass during the fall. Leatherjackets overwinter in the larval stage. As the weather warms in the spring, they continue to feed. Damage by their feeding may become especially noticeable in during the early spring months. During the day, leatherjackets mostly stay underground, but on damp, warm nights they come to the surface to feed on the aboveground parts of many plants. Leatherjacket feeding stops around mid-May.
Leatherjackets go into a nonfeeding stage just below the soil surface during July and August. From late August through September pupae wriggle to the surface and the adult crane flies emerge.
European crane fly larvae feed on the roots of grasses. Usually very little damage is done as plants have a remarkable ability to compensate from minor root damage. However, when populations are high (estimated to be about 25-30 larvae per square foot) damage to turf areas can be extensive.
They feed during the fall and into the spring of the following year. They stop feeding in May. Damage generally starts to be noticeable during the spring, caused by feeding that occurred the previous fall and winter. Damage can also occur when birds scratch at the lawn surface attracted to larvae.
Allow the surface of the lawn to dry out. The newly laid eggs of European crane fly are extremely sensitive to drought. If the surface of lawn is allowed to dry out thoroughly, the newly laid eggs will collapse due to dehydration. When the adult European crane fly are flying around they are laying eggs, so stop watering the lawn and allow the top 2-3 cm of soil to dry out.
Beneficial nematodes can be used as a preventative means of managing the European crane fly larvae. The nematodes must be applied shortly after the eggs have hatched and the larvae are small and immature. The opportunity for effective use of beneficial nematodes on European crane fly is generally in September and early October.
Integrated Pest Management with Pest Controls
When the European crane fly larvae populations become extreme and immediate action is required, a pest control can be applied. Rather than apply pest controls in a preventative approach in the fall, we recommend waiting until the following spring and monitoring the lawns for damage. The reason we recommend waiting until the spring is because the winter weather often reduces the population to levels that do not cause turf damage.
If you suspect that you have a European crane fly problem, but are unsure, contact your local Nutri-Lawn and we'll come out and take a look for you.