Geography
Affected Grass Types
Crane Fly Larvae
Tipula paludosa
Crane flies are long-legged insects that resemble oversized mosquitoes but do not bite. The adult stage is harmless; only the larvae feed on turfgrass. Larvae, called leatherjackets, live in the soil and chew on grass roots, crowns, and sometimes tender blades. Heavy infestations cause thinning turf, yellow patches, or large dead areas.
Identification
Adult crane flies resemble oversized mosquitoes with very long, delicate legs and slender tan-brown bodies measuring about 1 to 1.25 inches long. They are weak fliers and are often seen resting on walls, doors, or grass during late summer and fall. The damaging stage, however, is the larva—called a leatherjacket—which is a soft, gray-brown, wormlike grub lacking a distinct head capsule and growing up to an inch in length. Leatherjackets live in the thatch and upper 1–2 inches of soil, where they feed on grass roots and crowns. Infested turf often shows indirect signs such as thinning patches, birds pecking at the lawn, and grass that pulls up easily due to root pruning.
Life Cycle
Crane flies typically emerge as adults in late summer to fall, mate within hours, and females lay eggs in turfgrass. Eggs hatch within 1–2 weeks, and larvae begin feeding in fall, continue through winter, and feed most aggressively in early spring as temperatures warm. They pupate in late spring or early summer. Tipula paludosa generally has one generation per year, while Tipula oleracea may have two generations, increasing its potential for turf damage.
Damage Notes
Crane fly larvae feed on grass roots, crowns, and sometimes blades, leading to thinning turf, slow spring green-up, and irregular yellow or brown patches. In heavily infested areas, turf may pull up like loose sod due to root loss. Severe turf decline typically occurs when populations exceed 30–50 larvae per square foot. Secondary damage from birds or animals digging for larvae may further disrupt turf surfaces.
Control
Crane fly management relies on maintaining healthy turf through proper mowing, fertilization, irrigation, and thatch reduction, as dense lawns tolerate feeding better. Biological control options such as beneficial nematodes (Steinernema feltiae) applied in fall or early spring, and entomopathogenic fungi like Beauveria bassiana, can suppress larval populations. Where regulations allow, targeted chemical controls are most effective when applied in fall against young larvae and may include active ingredients such as bifenthrin. Treatments are generally recommended when larval counts exceed 25–50 per square foot.
Regional Notes
Crane fly damage is most common in cool, moist climates such as the Pacific Northwest of the United States and Canada, where both T. paludosa and T. oleracea thrive, and in parts of the northeastern U.S. and Midwest where moderate infestations occur. In Europe, these species are widely distributed and are long-recognized pests in regions like the UK, Ireland, Germany, and the Netherlands. High rainfall, mild temperatures, and extended wet seasons promote larval survival, while prolonged drought tends to reduce populations; climate shifts toward wetter, milder winters have allowed these pests to expand gradually into new areas.