MENACING LAWN OWNERS, ASSAULTING TURF
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
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.
WARM WEATHER PERIODS IN LATE WINTER OR EARLY SPRING CAN LEAD TO EARLY
FEEDING AND EXCESSIVE DAMAGE TO LAWNS.
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
- Keep up on crane fly biology-current
research is teaching us more every season. Visit the Crane
Fly website (http://whatcom.wsu.edu/cranefly/)
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
- 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
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 (http://pep.wsu.edu/hortsense/).
- 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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