Leatherjackets - Leather Jackets. Damage to plant roots. 

Letherjackets are the larvae of Cranflies and they feed upon roots or underground stems such as corms and tubers.

Nemasys - a biological control - can be used but the leatherjacket grubs can best be dealt with by ordinary cultivation procedures such as digging and hoeing. there are no soil insecticide treatments available. If the ground is empty of crops - such as is often the case on allotments, then a black plastic sheet can be laid down overnight, and the grubs will come to the surface, where they can be collected and dispensed with.

The adult Cranefly emerges from the soil in late summer, and soon get to work laying eggs in the soil - sometimes within a few days of becoming an adult! The eggs hatch into what we know as leatherjacket - though small at this stage - burrow into the ground and feed on roots and tubers throughout the autumn. They turn into 'leatherjackets' during late autumn, then overwinter in the ground, ready to resume feeding on plant roots as soon as the soil warms up in spring. Damage of the roots occurs and becomes noticeable in April - May. Whilst they remain underground in the daytime, they sometimes emerge at night - especially in damp and worm conditions.

Starlings and Blackbirds are happy to forage about in the borders and vegetable plot seeking out the tasty morsels we know and loath as leatherjackets!