EUROPEAN MARSH CRANE FLY

MEET THE PEST

The European marsh crane fly causes damage to grass, flowers and vegetable gardens. Lawns and golf courses experience the majority of damage. Damage is caused by the larval stage, or leatherjacket, when it feeds on roots during fall and early spring. Damage occurs at night when larvae move from the soil to the surface destroying young seedlings. Leatherjackets have a tough outer skin, are light grey to brown in colour and have black irregular spots on their body. The leatherjackets are usually contracted giving the appearance of a shorter, plumper caterpillar, however when stretched out, they are approximately 1 1/2 inches (3 3/4 cm) in length. The adult crane fly is somewhat similar in appearance to a mosquito, only much larger, with its body measuring approximately one inch (2 1/2 cm) in length. The crane fly has very long fragile legs, long light grey wings and is grey in colour. Adults are harmless to humans, but many people dislike large numbers of them hovering around their property.

LIFE CYCLE

The life cycle of the European marsh crane fly consists of egg, larva, pupa and adult stages. In late summer, adult crane flies emerge from the soil, mate and lay up to 300 eggs in the upper soil layer and then die. This occurs within a 24 hour period after emergence. The tough black eggs which are oval in shape hatch within two weeks. The eggs require moisture and a temperature of at least 14 degrees Celsius before hatching into the larval stage. Larvae experience four growth stages beginning in the fall, overwintering during the third stage and completing the final stage in the spring. Many leatherjackets do not survive the winter especially if they are exposed to cold, dry conditions. During early spring, when the final larval growth stage is complete, leatherjackets continue their eating frenzy until early summer when they enter the pupal stage. This stage involves a resting period where the adults develop and emerge approximately two weeks later. Only one generation is produced per year.

CONTROL

Monitoring

When found in large numbers, larvae of the European marsh crane fly can be severe pests. Monitoring for leatherjacket populations can be helpful in controlling them particularly when the temperatures begin to rise in the spring. To monitor populations, mark off one square foot of lawn, dig up the top layer and count the number of larvae present. If over 20 larvae are found on a square foot of soil, control measures may be necessary.

Physical

Try removing adults and leatherjackets manually. This can be achieved using a net, rake or handpicking. Crush or place those collected in soapy water. Another option is to use sticky traps. Good lawn care will also aid in control. This includes proper mowing height (they like to lay eggs in wet grass or near tall grass, thus keep height low), adjusting the pH and adding fertilizer to help minimize leatherjacket impact and allow the damaged turf to recover. A slow release nitrogen fertilizer is often helpful. Since damp conditions are necessary for egg and larval development, drainage should be considered when establishing a new lawn. The removal of wet conditions will reduce optimum conditions for the development of European marsh crane fly populations. If the lawn is established, additional drainage on a wet piece of property may lower the number of leatherjackets present.

Chemical

If physical control measures are not effective, use a pesticide which will have a minimal impact on both you and the environment. Consult with an expert at a garden center for pesticides available. Before using pesticides, consult the Backyard Bug Brigade Brochure which contains information on safe pest control.

Always use a registered domestic class pest control product labelled for European marsh crane fly control and carefully follow the label directions.