Crane Flies

Western Washington lawns only have one insect pest—the crane fly— and that insect is seldom a problem.

A recent survey of almost 200 lawns in Whatcom County found that none had enough crane flies to require any pest controls.

Not all crane flies are pests. There are 12-14 native crane flies that are beneficial in streams and forests. Only the European crane fly, an imported species, causes any problems.

Many people think they have a crane fly problem when they see yellow or brown patches in the lawn. However, these symptoms may have many causes, such as drought stress, animal urine or mower scalping.

A healthy lawn will easily recover from crane fly damage, even when the population is high. A few crane flies do not mean that you have a problem.

WSU Extension does not consider any treatment until there are at least 25 to 30 crane flies per square foot of lawn. A weaker lawn may be more susceptible to crane fly damage. The best crane fly control is to improve lawn health through proper fertilization, mowing, watering and other care.

Lawns with poor drainage are of concern. Water protects the larvae and also weakens the turf by rotting the plant's roots.

What you can do

• The best crane fly control is to improve lawn health through proper fertilization, mowing, watering and other care. A healthy lawn will easily recover from crane fly damage, even when the population is high.
• Check for areas in the lawn with poor drainage. Talk to us about how to correct the problem.
• Aerate your lawn to help the lawn roots take in air, water and nutrients. Ask us about seasonal aeration and fertilization.
• Water your lawn deeply and infrequently. The crane fly likes very soggy soil, so drying out the soil will help reduce its numbers.
• Attract birds. Many of them, especially starlings and robins, eat crane flies.
• Monitor your lawn. If you see any strange change in your lawn, such as a thinning or major yellowing, please call us immediately. We will come out and take a look.

What In Harmony can do

• As part of our lawn care program we can provide regular monitoring of your lawn for crane fly and take remedial action as necessary.

Reference

Crane Fly Pests of the Pacific Northwest, http://whatcom.wsu.edu/cranefly/