Crane Fly Problem

How to Solve a Crane Fly Problem

The Crane Fly is a turf damaging insect that can cause damage in all species of cool season turf grass. Crane Flies can be found in parts of the American Northwest, Northeast, and also parts of Michigan. The Crane Fly can be a big problem in the Seattle area! Approximately 10% of the lawns that we work on suffer from crane fly infestation.

But did you know that it is not the Crane Fly that causes damage to your lawn? The damage is caused by the larvae that the Crane Fly leaves behind. If you have areas in your lawn that look like this picture to the left, then it is likely that you have a lawn that is being damaged by Crane Fly Larvae, and once they start feeding on your lawn, they will keep at it until either your lawn is destroyed, or they are.

Identifying the Crane Fly:

Adult crane flies look like giant mosquitoes. They have slender bodies that are brownish-tan in color and feature one pair of long, smoky-brown wings. They also have very long legs. Crane Fly larvae are small and worm-like, ranging in color from olive-gray to greenish-brown. The tail end of the abdomen bears six fleshy, finger-like lobes. They also have a black-pointed head that withdraws into the front part of the body when disturbed.
Crane flies lay their eggs in grass in the summer or early fall. The eggs hatch into larvae or maggots, known as ‘leatherjackets’ because of their gray-brown leathery skin. Crane fly larvae live in the soil and feed voraciously on the roots, shoots and crowns of grass plants during the fall and following spring. Eventually the larvae grow to be 1.5 inches long.

Most of the lawn damage caused by Crane Fly larvae occurs during the spring, when larvae are feeding on the roots and leaf blades of your grass. The results of these feeding habits are recognizable areas of sparse turf, missing foliage and general bare areas in affected lawns. Upon closer inspection these areas often reveal large numbers of larvae in the thatch and upper soil. Crane Flies are considered a pest to turfgrass in the Northwest because they can quickly destroy your lawn.

The Crane Fly Life Cycle

Crane Flies produce one generation per year. The eggs are laid just under the soil surface and require adequate moisture to survive. Receiving the moisture needed to survive during the spring is not a problem in the Seattle area! Because the larvae cause the most damage to your lawn during the spring, most of our customers are shocked to see these large, ugly, brown patches suddenly appear in their lawn. These ugly brown patches of unhealthy, or dead grass, are evidence that the Crane Fly larvae have been feasting on your lawn.

The Solution

The solution to the Crane Fly larvae problem is first to kill the Crane Fly larvae by applying a product that has the right ingredients to kill this pest dead in its tracks. The product we use is called Mallet Insecticide which has been trusted for decades by golf course superintendents, arborists, lawn care operators, nursery professionals, and parks and recreation directors. This product is a granular formulation that contains the active ingredient Imidacloprid, which is a systemic neurotoxin that affects a pest’s central nervous system. Once a pest comes into contact with Mallet, the active ingredient triggers paralysis that leads to death. Imidacloprid binds more strongly to the insect’s neuron receptors, making it effective at killing nuisance insects. Once the larvae have been killed we will then proceed with a full lawn renovation. This will include dethatching your lawn to remove moss, thatch, and dead grass, then aeration, followed by applying fertilizer, and optional soil conditioner and Overseeding.