**Leatherjackets** are the tough, grayish-brown, legless larvae of the **Crane Fly** (family Tipulidae). They are subterranean pests, primarily of **turfgrass** and various field crops. Leatherjackets cause damage by chewing on the roots and crowns of grasses and crops just below the soil surface, resulting in bare patches of dead vegetation. They are particularly troublesome in damp, poorly drained soils and during mild, wet winters where their feeding activity can be prolonged.
Taxonomy and Classification
Leatherjackets belong to the order Diptera (flies). They undergo complete metamorphosis. The Crane Fly adult is a long-legged, mosquito-like fly (often mistaken for a giant mosquito), but it is harmless and does not bite. The larva (Leatherjacket) is named for its thick, leathery, gray skin. The life cycle usually lasts one year, with the larvae being most damaging in the spring after overwintering.
Physical Description
Mature Leatherjackets are stout, worm-like larvae, 1 to 1.5 inches long.
- **Larva (Key ID):** Gray, brown, or dirty-green; legless; cylindrical; and tough-skinned (leathery). They lack a distinct head capsule, with chewing mouthparts retracted into the body.
- **Adult Crane Fly:** Harmless, very long-legged fly, often seen clumsily flying low over lawns in late summer/early fall when they emerge to lay eggs.
- **Damage Sign:** Irregular patches of grass thin and die, often appearing “chewed” at the base of the stems (the crown). Secondary damage from birds (starlings, crows) and skunks probing the lawn for the grubs is common.
Distribution and Habitat
Leatherjackets are common in temperate regions, particularly in the UK, Europe, and North America (especially the European Crane Fly, *Tipula paludosa*, which is invasive). Their habitat is primarily the root zone of turfgrass, pastures, and poorly drained arable land. They can sometimes be seen emerging from the soil on damp, mild evenings to feed on grass crowns.
Behavior and Conflict
The conflict is significant turf and crop damage.
- **Surface and Subsurface Feeding:** They feed on roots, subterranean stems, and occasionally pull entire grass blades down into their burrows to feed, leaving small holes.
- **High Moisture Preference:** Infestations are usually worst in areas of the lawn that remain consistently wet.
- **Secondary Damage:** Birds and other animals cause visible damage to the lawn when probing for the large, high-protein larvae.
Management and Prevention
Control is integrated pest management (IPM), targeting the young larvae in the fall or the older larvae in the spring.
- Improve soil drainage to make the environment less favorable for the female fly to lay eggs.
- Reduce lawn watering during peak egg-laying periods (late summer/early fall).
- Apply **Entomopathogenic Nematodes** (specifically *Steinernema feltiae* or *S. carpocapsae*) to the lawn in the fall or spring when the larvae are actively feeding. This is often the most effective method for home lawns.
- Targeted insecticides may be used in the fall against newly hatched larvae or in the spring against the actively feeding, overwintered larvae, applied according to professional recommendations.
Conservation and Research
Leatherjackets are managed as high-priority turfgrass and agricultural pests. Research focuses on optimizing the application timing and efficacy of biological control nematodes and identifying resistant turfgrass varieties.