Crane flies, often mistaken for giant mosquitoes or “mosquito hawks,” are common lawn pests that can cause significant damage to your grass. While adult crane flies are harmless and feed on nectar, their larvae, known as leatherjackets, are the culprits behind unsightly brown patches and thinning turf. Understanding how to control crane flies is crucial for maintaining a healthy and vibrant lawn.
Identifying Crane Flies and Leatherjackets
Knowing what crane flies and their larvae look like is the first step in effective control.
Adult Crane Flies: These insects are most active during twilight hours and are attracted to moist environments, especially irrigated lawns. They are characterized by their delicate, veined wings, which typically span about an inch, and their long, stilt-like legs.
Leatherjackets (Crane Fly Larvae): These plump larvae are grayish to olive-brown and can grow up to 1.5 inches in length. Leatherjackets have a tough skin, giving them their name, and resemble headless, legless caterpillars or grubs. They live in the soil and feed on grass roots and blades.
Recognizing Crane Fly Damage in Your Lawn
Leatherjacket feeding habits can lead to noticeable damage to your lawn. They feed on all parts of the grass plant, from the roots and crowns to the blades themselves.
Signs of Infestation:
- Thinning Grass: One of the first signs is a general thinning of your lawn, especially in spring.
- Brown Patches: Irregular brown patches will begin to appear as grass weakened in the fall starts to die off in the spring. Damage is most prominent in the spring.
- Visible Larvae: To confirm leatherjacket presence, use a shovel to lift a section of damaged grass. You will find the leatherjackets feeding in the soil beneath the grass layer.
- Increased Bird or Animal Activity: Birds, skunks, and raccoons may start digging in your lawn as they prey on leatherjackets, indicating a potential infestation.
Effective Methods to Kill Crane Flies and Leatherjackets
Controlling crane flies involves a combination of preventive and active treatments, primarily targeting the damaging leatherjacket larvae.
Preventive Lawn Care
While not directly killing crane flies, certain lawn care practices can make your lawn less attractive to them:
- Proper Watering: Avoid overwatering your lawn, as crane flies prefer moist conditions for egg-laying. Water deeply but less frequently.
- Thatch Management: Excessive thatch can provide a favorable environment for leatherjackets. Dethatch your lawn regularly to reduce this layer.
- Healthy Lawn Practices: Maintain a healthy lawn through proper fertilization, aeration, and mowing. Strong, healthy turf is more resilient to pest damage.
Active Treatments to Kill Leatherjackets
For existing infestations, direct treatments are necessary to kill leatherjacket larvae. Insecticide applications are most effective in early spring and late summer/fall.
- Spring Treatments: Target leatherjackets that have overwintered in the soil before they cause significant spring damage.
- Fall Treatments: Aim to control newly hatched larvae and emerging adults in late summer and fall to prevent future infestations.
Recommended Insecticide Products (Based on Original Article):
GardenTech® products with the active ingredient Sevin® are effective for controlling leatherjackets. These products work by contact to kill crane fly larvae.
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Sevin® Insect Killer Granules:
- How it works: Kills leatherjackets both above and below the soil surface. Provides extended protection against leatherjackets and other listed pests for up to three months.
- Application: Apply using a standard lawn spreader for even coverage. Water immediately after application to activate the insecticide and move it into the soil where leatherjackets are present.
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Sevin® Insect Killer Concentrate:
- How it works: Kills adult crane flies and leatherjackets by contact, and offers continued protection for up to three months against listed pests.
- Application: Use a pump-style sprayer to apply to lawn areas where crane flies are present or damage is observed. Ensure thorough coverage of grass and plant surfaces.
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Sevin® Insect Killer Ready to Spray:
- How it works: Similar to the concentrate, it provides contact kill and extended protection.
- Application: Attaches directly to your garden hose for easy mixing and application. Spray affected areas thoroughly, ensuring complete coverage to treat existing pests and prevent further damage.
Important Note: Always read and carefully follow all product label instructions for safe and effective use, including application rates, safety precautions, and target pests.
Tips for Successful Crane Fly Control
- Timing is Key: Apply treatments at the recommended times (early spring and late summer/fall) for optimal results.
- Watering After Granules: Watering is crucial after applying granular insecticides to move the active ingredient into the soil.
- Monitor for Signs: Regularly check your lawn for signs of leatherjacket damage, especially in spring.
- Act Promptly: If you notice increased bird or animal activity or suspect leatherjackets, treat your lawn promptly to prevent severe damage.
By understanding the life cycle of crane flies, recognizing the signs of leatherjacket infestation, and implementing appropriate control measures, you can effectively protect your lawn from these damaging pests and maintain a healthy, beautiful outdoor space.
