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Monitoring and decision making You can investigate and find out yourself the level of crane fly larvae in your lawns. Research has given us thresholds or levels of infestation that helps us decide to relax or take further action. Here is what to do; In February or March select three or four random locations on your lawn. This time of year is selected so to let the normal winter death of larvae to take place. With a shovel or spade cut three sides of a six inch by six inch square about 1-2 inches deep and peel back the sod to expose the bottom of the lawn grass. Count the number of leatherjackets you find. They will be right there in front of you. Multiply the number of larvae found in each location by four. This gives you the number per square foot, the reference for recommendations. If your count exceeds an average of 25 larvae per square foot in a healthy lawn, then some management action may be appropriate. The action threshold for weak lawns is lower - about fifteen larvae per square foot. I want to reiterate that the most important action is making and keeping your lawn healthy and vigorous. See the recommendations above. If you have taken all of those actions, and you find high levels of crane fly leatherjackets in the spring, then you might wish to consider a further step of an insecticide. Or you may decide to convert your lawn over to other forms of ground-cover will be more successful in your yard. There are a number of insecticides that are registered by the EPA for use by homeowners on crane fly. The two most commonly used are chlorpyrifos (Dursban) and diazinon. Both are available in granular and liquid form, although some liquid formulations are not available to homeowners, because special licensing is required to purchase, handle and apply them. Due to its toxicity to birds, WSU does not recommend diazinon for crane fly control. . Chlorpyrifos is the preferred material and is very effective against this pest. Granular formulations are usually safer to the user because there is a smaller percentage of the "active ingredient" in the formulated product and therefore the likelihood of exposure and possible harm to the applicator is reduced. It is important to avoid the tendency to over-apply the granules to the point where they are easily visible on the lawn surface. Apply according to the label directions. Liquid formulations are equally effective and may be preferable because there is less tendency to over-apply. Regardless of the formulation used, care must be taken to use them properly so that they reach the target pest (crane fly larvae in the soil) and do not effect non-target species near the home or in nearby waterways. Unfortunately, both chlorpyrifos and diazinon have recently been detected in surface waters in the Puget Sound Basin, including Lake Whatcom. If you live in the Lake Whatcom watershed, please consider the special responsibilities of affecting the water supply for close to 100,000 people with your actions. Other choices on the horizon There exists a number of different kinds of microscopic insect killing nematodes (roundworms) that have the potential for seeking out and killing crane fly larvae in lawns. Unfortunately, in the past, research has indicated that these are not effective in the cool soils we have in the Pacific Northwest. Recently new types have been identified that are supposed to be more effective at cooler temperatures. We intend to conduct some research on the effectiveness of these new types right here in Whatcom County soon. If they appear to be effective they will become a highly desirable option for those lawns that monitoring indicates a serious threat from crane fly larvae. previous				In this article... Introduction Smart Management Grow healthy lawns The cycle of life Monitoring and decision- making Printer-friendly format combines all sections of this subject See also: "ECF & CCF" - by Sharon Collman "Managing ECF in Whatcom Co." - by Todd Murray and Scarlet Tang "ECF- Management History & the loss of Dursban" - Antonelli and Stahnke
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