IPM Crane fly solutions

Asked February 7, 2017, 6:22 PM EST

Hello! Since moving into my home last year, it's become apparent that we have crane flies in our yard. They have not destroyed my yard, but my neighbor has previously had issues and because of this uses a yard service and an arsenal of chemicals to deal with this. I would like to use an integrated pest management approach and have heard about beneficial nematodes. Where can I buy them in the metro area? Any tips for application methods and timing?

Multnomah County Oregon

2 Responses

In spite of what you may have heard, European crane flies seldom damage local lawns. Further, seeing numerous flying adults in fall do not guarantee damage the following spring. It will be helpful if you can describe the damage as well as when and where it occurs.

People often complain of brown spots, thin lawn, or dead areas. But more often than not, a water shortage is the cause, perhaps because of insufficient water in sunny areas; uneven water distribution; and/or a sprinkler which has become blocked by plant growth. (Overall, the recommendation is to apply an inch of water per week through the dry summer months.)

Turf specialists say damage is unlikely unless the total number of larvae exceeds 50 per square foot. Here’s how to determine how many larvae are present in one square foot:

1. Remove a 6-inch square of lawn that’s 2 inches deep.

2. Dig through the root mass to remove and count the larvae.

3. To determine the total per square foot, multiply by 4.

A healthy lawn is the best defense against crane fly damage. For details, refer to “Practical Lawn Care for Western Oregon” at https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/ec1521.pdf.

Another critical management tool against crane flies is to limit, or even stop, lawn irrigation after Labor Day. The reason: Limiting supplemental water in September means that the freshy laid eggs are unlikely to hatch.

If pesticides are to be applied, the most effective time is during the December-May window when the larvae are feeding on grass roots and crowns.

Additional resources for you:

- FAQ for Crane Flies in the PNW http://whatcom.wsu.edu/cranefly/faq.htm

- Managing the European Crane Fly in Whatcom County: An illustrated brochure which explains the crane fly life cycle. http://whatcom.wsu.edu/cranefly/articles/crane_fly.pdf

If you have images of the damage, please attach them when you apply to this email.

And, if you have additional questions, please ask.

I just realized that I didn't respond to your question about where to obtain beneficial nematodes. They're typically available at larger garden centers such as Portland Nursery, Al's Tree & Shrubs, First Light & Seven Dees. The package is a box with a certificate which is to be mailed to the distributor. Unfortunately, the time to apply beneficial nematodes is fall. See http://extension.oregonstate.edu/gardening/crane-fly-are-leatherjackets-munching-your-lawn