Distant: Damage appears in the spring after the turfgrass begins to green. Infested turf may be thin and brown or closely cropped in patches. Small patches may coalesce into large patches of bare soil or dead turf (Images D, E, and F).
Up close: Patches of scalped or dead turfgrass; leatherjacket larvae in thatch or top layer of soil.
When damage would be found: Mostly in the spring
Host: All cool-season turfgrasses
Site: Craneflies prefer turf growing in moist soils with high organic matter
Description of damaging stage: The larvae (called leatherjackets) are grayish-brownish, and look like a thin caterpillar with no legs and no visible head. Most of the damage is caused when they are full grown in the spring (Image G).
Sampling: If hundreds of cranefly adults were observed, or if cranefly damage has been observed in your area in the past, observe the turf at night with a flashlight to see leatherjacket larvae on the surface, or sample by digging up several 1 ft2 areas of the turf. Break the soil apart and look for leatherjackets. Leatherjackets will be 0.25 to 0.5 inches long in the fall, and 0.75 to 1.0 inch long in the spring. More than 15 per ft2 is likely to cause turf injury in home lawns and golf course roughs, while more than 5-10 per ft2 could cause injury to fairways, tees, or greens.
Preventing Pest Injury to Turfgrass: Home lawns, recreational turf and golf course roughs can be managed to avoid insect injury without insecticides by using proper fertility, mowing at a height of 3.0 to 4.0 inches, and watering during dry periods. This will build a dense stand of turf and a diverse community of insects that will keep turf pests under control. All lawns in Michigan will typically start off lush and green in the spring and will go dormant and turn brown during periods of little rain. Information on the use of insecticides to treat turf pest problems is only meant to be used for the unusual cases where turf damage from pests becomes unacceptable. Even then, insecticides should only be used in areas of a lawn with severe turf damage, and only until a dense turf is re-established.
Using insecticides: Use insecticides judiciously, temporarily, and only in response to unacceptable turf injury. Many insecticides are poisonous if ingested, and therefore must be stored in places where they cannot be found by children. Use the rate recommended on the label for the pest you are attempting to control. Wear rubber gloves, safety glasses (or goggles), rubber boots, long pants and long sleeved shirts when mixing and applying insecticides. The most caution is needed when mixing a concentrated insecticide in water, because skin contact with the concentrated insecticide in the original container is more dangerous than contact with the diluted insecticide after mixing. Water the turf immediately after applying the insecticide to wash it to the base of the plants or into the soil and allow the turf to dry before allowing access by people and pets.
Chemical Control of Cranefly: The ideal situation is to find the leatherjackets in the fall and to make a fall application (late September to mid October) of chlorantraniliprole, carbaryl or clothianidin. This will prevent damage in the spring when the larvae are likely to cause the most damage. If crane fly damage is not discovered until April or early May, apply dinotefuran at that time.