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Crane Fly Frequently Asked Questions 
This page contains questions that are commonly asked about crane flies. Feel free to ask more (ask a question)! Check back often!

What is a crane fly?adult crane fly

There are many kinds of crane flies. In the Pacific Northwest, we have many native crane flies that are beneficial decomposers in streams and forests. However, we do have some exotic crane flies that came from Europe. These crane flies can do damage to our lawns.

Why are some crane flies pests?
crane fly larva

The larvae of pest crane flies, also known as leather jackets, feed on the roots of plants, mainly turf grass. Sometimes crane fly populations get high enough to cause damage to lawns.

I have hundreds of crane flies bouncing around in my yard, how do I get rid of them?
crane fly eggs

These are the adults of the crane fly. During summer, adults emerge, mate and deposit eggs. It is not practical to try to kill crane flies at this time. Keep window screens sealed and screen doors shut to keep flies from becoming an nuisance in your house. Adult crane flies do not damage your lawn, nor do they bite or sting. They are harmless.

What are my chances of having a crane fly problem?

For the average lawn, crane flies are rarely a problem. In a 2002 survey done by Whatcom County Master Gardeners, they found that 90% of Lake Whatcom watershed residents didn't have any crane flies at all! The rest of the lawns had few crane flies and no crane fly problems.

How do I recognize crane fly damage?
crane fly damage

Leather jacket feeding can cause brown patches in lawns. This is mainly due to the root feeding of larvae (leather jackets). However, many other environmental conditions and pests can do this too. If you see symptoms, contact your local Master Gardener at your county's Cooperative Extension.

How do I know that I have a problem with crane flies?

crane fly sampling
Before any decisions are made, the best thing to do is figure out if you even have a problem by sampling. Sampling crane fly populations is easy and takes just a short time.

What should I do about crane flies in my lawn?
crane fly pupa
You will need to first decide if you have a crane fly problem. Most of the time, you don't need to do anything! Vigorous lawns recover from crane fly damage. If action is needed, apply treatments in early to mid-April. Do this only after you've sampled your lawn for crane flies. If the problem is very bad, consider other methods for managing crane flies such as replacing the problem area with a lawn alternative plant.

How do I know what the crane flies are doing?

Crane fly activity and life stages change with the seasons. Visit the "Crane Fly Calendar" to see what the European crane fly is doing and what you should be doing.

Why do I see crane fly adults at times different than what the Crane Fly Calendar shows?
adult crane fly

Recently, there has been a new European crane fly discovered in the Pacific Northwest, known as the 'common crane fly.' We don't know much about this crane fly yet, but it does not appear to be a serious pest. The new crane fly is very difficult to distinguish from the European crane fly without a microscope (for more info). However, their life cycle is a bit different.
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