Identification

Leatherjackets are the larvae of cranes flies which are very familiar to advisers and farmers. The adults are weak fliers with long gangly legs and a long slender abdomen, known to many as `Daddy long-legs`,. Whilst the adults do not affect crops, leatherjackets are an important pest of farm crops. Leatherjackets are greyish / brown and up 40 mm long. They do not have legs or an apparent head and they have a tough leathery outer skin. Leatherjackets can be readily found in the vicinity of recently damaged plants.

Symptoms

Whilst cereal seed can be hollowed out greater damage is caused by the leatherjackets moving along the rows of plants and feeding on the stems at or below ground level. The first symptoms appear as yellow, wilted plants which can lead to individual plant loss as well as loss of crop in patches.

Damage to young beet plants is caused by the leatherjackets moving along the rows of plants and feeding on the stems and roots at or below ground level. The first symptoms appear as yellow, wilted plants which can lead to individual plant loss as well as loss of crop in patches.

Life-cycle

Eggs are laid in grassland areas and after about 10 days the leatherjackets emerge and start feeding on plant roots. During mild winters feeding can continue through until spring when activity is at its peak and when fully mature the leatherjackets pupate in mid - late summer. The pupae have the ability to `wriggle` to the top of the soil to allow the adult flies to emerge in late summer, pupal cases can occasionally be seen protruding from the soil surface. There is usually only one generation per year.

Importance

Leatherjackets are a widespread and important pests of a wide range of crops including cereals, grass and root and vegetable crops. Where populations are high whole crops can be completely lost.

Threshold

The greatest risk is for spring cereal crops after grass. ADAS threshold for spring cereals are 50 leatherjackets /m2 or 5 leatherjackets / m row.