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?
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?
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?
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?
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
county's Cooperative Extension.
How do I know that I have a problem with crane flies?
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?
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
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?
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.