Crane fly treatment
Our lawn care provider has told us we have a crane fly problem that needs attention. Some of our homeowner association (HOA) members want us to spray a chemical on the bad spots, but others do not want to apply any chemicals, citing health and environmental concerns. As the president of our HOA, I must get our board to make a decision very soon. Can you recommend what we should do?
Marion County Oregon
While crane fly can be a problem, action thresholds are 25 larvae per square foot. If you do not have populations exceeding these levels, treatment is not necessary. To determine your population, cut a 1 ft x 1 ft x 3 inch deep piece of sod, and then flip the sod over. The larvae will be visible at this depth.
If populations exceed 24 per sq ft and treatment is needed, I would apply a product with the active ingredient fipronil. While this product is effective on crane fly larvae, it is also a low-impact pesticide (http://www.ipmnet.org/tim/IPM_in_Schools/IPM%20Materials/Low_Impact_Pesticide_List.pdf) approved by use in Oregon schools.
The best time to apply the product is now! You can apply into April, but when considering the insect's life cycle, winter applications are the most effective.
Is spraying necessary for all the lawn area or just the obviously infected areas?
No, apply to areas where you are seeing damage/reduction in turf density. Crane flies prefer moist soil, which is often the low-lying, shady area in your lawn.