The Impact Of Crane Flies On The Pacific Northwest

Updated for 2023

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At the tail end of every summer, fantastical beasts raise from the the turfs of the Pacific Northwest, almost immediately finding counterparts so they can mate. After a life largely made up of eating and living underground, you might seek out someone’s touch as soon as possible, too.

These beasts are more formally known as crane flies. (OK, maybe they’re not really beasts.)

Since the insect’s introduction to the area, crane flies have caused damage to lawns all across the Pacific Northwest.

The female crane flies quickly lay eggs right where they just emerged less than 24 hours previous: the doldrums of the damp soil. The process then starts all over again: eggs hatch, the larvae of the crane flies feed and destroy lawns for part of the year, and then pop up again in August and September to live for the best two weeks of their life in the temperate, wet climates of the Pacific Northwest.

Crane Fly Origins in the States

The European version of the insect migrated to the area with help from the shipping business. Vegetables that were grown in northern European countries were shipped over the America, and crane flies attached to the food and fed off them until they got to the Pacific Northwest, where they found a new home. The species that helped control the crane fly population in their previous home were no longer present, so the beasts were able to develop and spread in the right climates.

Crane flies are also known as leatherjackets or Daddy Long Legs because of their physical attributes at various stages of life. Crane flies are pretty big insects, usually about one-to-two inches long with six long, skinny legs once they’re in their adult stages.


Crane flies look a little like mosquitoes with stilts. They also have hard shells in the larval stage, thus the leatherjacket name. Despite their menacing nicknames, they don’t bite and are basically harmless to humans. They can affect the appearance of humans’ homes, though.

What Kind of Damage do Crane Flies Cause?

Since the insect’s introduction to the area, crane flies have caused damage to lawns all across the Pacific Northwest. Crane flies feed on the roots and crowns of grass and vegetables like potatoes, beets, and cabbage, and they spend almost all of their life underground feeding on these roots. Grass grows even quicker in moist conditions, so crane flies have more to eat when there is a particular rainy season.

After the eggs hatch in late-September, they feed on the ground for a couple months before laying dormant for the winter. Then crane flies start feeding again as larvae in the spring months (March through May), which is when most of the effects of crane flies’ feeding start to show on lawns. They stop feeding for June and July before emerging in the summer and briefly doing more damage to the roots.


Overall, “usually very little damage is done to plants by these creatures, including lawn grasses, because plants have a remarkable ability to compensate for minor root damage,” Jack DeAngelis of Oregon State University said.

Grass often gets patchy and dies when crane flies are present. “This dieback is especially noticeable in the spring,” OSU’s website dedicated to cane flies says. “Damage can also occur when birds come in and scratch at the lawn surface looking for larvae to eat.”

How Do I Get Rid of Crane Flies?

Due to their short lifespan once they’re adults and scheduled bouts of feeding when in the larvae stage, crane flies often die or stop eating before too much damage on lawns can be done. Their effects are still a sight for sore eyes, so there are steps to take before the spring feeding season to check if your lawn is infested with crane flies.

The easiest step in discovering if crane flies are in your lawn is cutting out a one-foot square patch of your lawn. (It’d be wise to cut out the patch in a place that isn’t too visible to a passerby, just in case you end up not replacing the patch.) Turn the patch over and check for crane fly larvae. They may be difficult to find because they’re embedded in the soil, but don’t worry—they don’t bite.

If the one-square-foot patch of lawn has more than 25 crane fly larvae it in, then you may want to begin pre-emptive steps so you can kill the crane flies before the effects on your lawn start to show.


These measures can include:

  • Turning off irrigation systems:Shutting off watering systems at certain times of the year—especially around September, when crane flies lay eggs—can prevent giving crane flies the best environment to thrive.
  • Spraying insecticides:Use sprays with ingredients like bifenthrin or pyrethrins. These help kill the crane flies before they do too much damage. They also can be poisonous to birds and bees, which feed on crane flies, so be sure to spray at night when less of these animals are feasting on the beasts.
  • Renovating your lawn: OSU’s Extension Program suggests that you can do a complete overhaul of your lawn if there are more than 25 crane flies per square foot. The new grass won’t be infested with the insects, and then you can take preemptive steps once you have your new lawn.
    If you already see the damage, that’s okay. The damage is done, and the crane flies have probably already died out by then or they will soon.

“They will die soon so there’s no need to spray,” said Brian McDonald, the senior research assistant at OSU’s turf program. Basically, the pesticides and insecticides will only do more damage to your lawn and the species living around the area.

WCrane flies sometimes make their way to sidewalks and driveways while still in the larvae stage. If they aren’t picked up by other animals, they might just die there. “I would dispose of them because they’ll begin smelling really bad once they’re dead,” McDonald suggests.

Other Options for Crane Fly Control

If all else fails and crane flies continue to be an issue, it’s important to contact a professional. Improper use of chemicals to try to dispose of crane flies can only make the matters worse and cost you more money to fix in the long run.

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