European crane fly

The damaging stage is the larva, called a leatherjacket — a legless, gray-brown, tough-skinned grub up to about 1 to 1.5 inches long found in the thatch and upper soil; the long-legged, mosquito-like adult crane fly does not damage turf. Detect leatherjackets by soil sampling or a soap/saltwater flush in fall and spring. Two invasive species, the common European crane fly (Tipula paludosa) and marsh crane fly (Tipula oleracea), are the turf pests.

Thinning, yellowing turf beginning in late winter that can progress to bare, dead patches in spring, especially in wet, low areas; heavy root and crown feeding by leatherjackets weakens the stand, and surface feeding on damp nights leaves chewed, ragged turf. Birds digging for larvae can add to the visible disturbance.

Crane flies are flies with complete metamorphosis. Tipula paludosa has one generation per year: adults emerge and lay eggs in late summer/early fall, larvae feed through fall, overwinter, reach maximum size by midwinter, and do the most damage in spring before pupating. Larvae feed on roots, crowns, and shoots, and moist conditions favor egg survival and larval development.

Damage is concentrated in the cool, wet maritime climate of the Pacific Northwest (and other cool, humid regions) in wet, low-lying, poorly drained turf. Thinning typically begins in late winter and progresses to severe turf loss in spring (April-May) as overwintered larvae feed heavily; excess moisture and thatch increase risk.