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Crane FlyCranefly

Aliases Bugsy, European Crane Fly; Mosquito Hawks; Tipula paludosa

Hangout: Young stay protected in soil of lawns; adults bob around lawns and porchlights in August and September
Physical Features: Young are wormlike with tough brownish skin and care called "leatherjackets"; adults are about 1: long with wings and spindly legs, and look like giant mosquitoes

Life Cycle
Leatherjackets are below-the-belt villains, attacking both the roots and tops of grass blades in the spring. In mid-May, European crane flies cease the attack and retreat to hideouts just below the soil, until August or September. When they emerge as adults, they look intimidating, resembling overgrown mosquitoes. However, adults won't attack your lawn. They only emerge for mating and egg laying.

Shoo Fly -Don't Bother Me!

1. Patrol the area

  • In late February or early March, after cold winter temperatures have killed off some trespassers, it's time to survey the survivors. Select three or four random locations on your lawn.
  • With a shovel or spade, cut three sides of a 6"x 6" square about 1-2 inches deep and peel back the sod to expose the bottom of the grass.
  • Count the number of leatherjackets you find. They'll be in the root zone and you may need to knock it apart to get the little critters out.
  • Multiply the number of larvae found in each location by four. This gives you the number per square foot, the reference for recommendations.
  • Replace each sample so it can grow back into the ground.
    Keep an annual record of the number of leatherjackets you track down.

2. Make a positive I.D.

  • There are several species of crane fly in this area. In order to effectively control them, you must know the exact species so you can properly counterattack. Wrangle up an adult crane fly and let a Master Gardener help you identify it.

3. Do a thorough background check

  • Keep up on crane fly biology-current research is teaching us more every season. Visit the Crane Fly website ( to see the most current information.
  • Become familiar with the crane fly lifecycle, and what can bring them to their deathbed. For example, many leatherjackets freeze to death in the winter.

4. Determine the danger level

  • Consider the health of your lawn. Healthy lawns can withstand well over 40 leatherjackets per square foot with no assistance. The action threshold for weak lawns is lower-about fifteen leatherjackets per square foot.
  • After May 15, the damage has been done. Focus on preventing damage next year by taking good care of your lawn, but don't bother killing this generation of crane fly.

5. Make a plan

  • Do-Nothing Method
    According to a survey done in 2001, no lawns in the Lake Whatcom watershed had cranefly at high enough levels to do damage. Leatherjacket populations will diminish during cold winter months and between mid-March and mid-May because of predators and other natural causes. As much as 50% of the invasion can be wiped out without your help. So if you don't have much damage, wait it out.
  • Manipulative Measures
    -Making and keeping your lawn healthy is the most important thing you can do in the fight against crane fly. For details on caring for your lawn, see Keeping Your Lawn and Lake Whatcom Healthy.
    -Disrupt crane fly habitat and promote a healthy root system by removing thatch every few years and increasing oxygen flow through aeration.
    -As semi-aquatic creatures, leatherjackets love soggy lawns. Keep your lawn well drained or plant something else in waterlogged areas.
  • Secret Agents
    Robins, starlings, parasitic nematodes and ground beetles search and destroy leatherjackets. Avoid using pesticides that could poison your allies.

Armed and Dangerous

  • WSU entomologist Art Antonelli estimates that 90-95% of chemical applications for crane fly are unnecessary. If you've sampled your lawn and know that you're one of the few with an actual crane fly problem, you may decide to arm yourself with a chemical substance. Apply suitable chemicals between April 1 and 15. Be sure the chemical is legal for home use on lawns. Information regarding chemical treatment of crane fly can be found on the WSU Hortsense web page (
  • Follow use, storage, and disposal directions on the label. It's the law.
    Find out if the pesticide you are using is deadly to bees or birds. Avoid harming innocent bystanders-birds are one of your biggest partners in the struggle against crane fly! If you are using a chemical toxic to bees, at least pull out any flowering weeds or clover they may visit later. Spray in the evening when bees aren't around.

6. Evaluate the results

  • After recording the annual leatherjacket count, note if and where any damage was seen that spring. This will help you determine the tolerance level of your lawn. Also record the effectiveness of any steps taken against crane fly.

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For more information, contact Scarlet Tang or Todd Murray
WSU Cooperative Extension (360) 676-6736
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