Leatherjackets

Key Points

  • Leatherjacket infestations can devastate crops that are attacked
  • Crops following grass represent the highest risk of economic damage
  • Use Risk Assessment Charts to establish fields at most risk
  • Soil sampling indicates pest levels in individual fields
  • Dursban WG is established as the product of choice for control of Leatherjackets

Introduction

leatherjacket

Leatherjackets are the larvae of the Crane fly — Tipula paludosa — or ‘Daddy Long-legs’ and cause widespread damage to vegetables, root crops, winter and spring cereals, and grassland. Feeding usually takes place just below the surface of the soil, with roots and underground stems being destroyed. In vegetable crops wilting of plants following destruction of the roots is normally the first evidence of attack. This can normally be easily confirmed by finding Leatherjackets in the soil near the damaged plants.

Biology

Adult females of the Common Crane fly are seen on the wing from late July to September. They lay around 300 eggs in the soil surface which hatch within 2 to 3 weeks. The larvae immediately begin feeding voraciously on roots and underground stems, particularly during periods of mild weather throughout winter, but also as the temperature rises in the early spring months.

The larvae reach maturity during late May and in to June. They then pupate in the soil and adults emerge again in late July to early September. Leatherjacket larvae are normally grey-brown in colour, soft, fleshy and legless. They can reach 50mm in length when fully grown.

Crops following grass leys, permanent pasture or arable crops with a grass weed infestation are particularly at risk. Ploughing grassland in July and subsequent cultivations can destroy up to 50% of Leatherjackets.

Product Choice

The first action must always be to carry out a Risk Assessment. This can be done using the Dursban* WG Leatherjacket Risk Assessment Chart (52KB PDF). If the Risk Assessment indicates treatment is justified, Dursban WG should be applied at 1.0kg/ha in a water volume of 200 – 1000 litres per hectare when damage is seen or predicted. Controlling Leatherjackets early gives the best economic response to treatment but application during periods of prolonged frosts should be avoided as Leatherjackets are less active near the soil surface under these conditions. Applications when temperatures are above 5°C give best results.

Examples of the actions required as a result of carrying out a Risk Assessment are shown below.

Risk Action
>12 Apply Dursban WG at 1.0kg/ha as routine.
8 – 12 Check fields for signs of damage or presence of larvae. An early indication of Leatherjackets can be given by the presence of birds, particularly rooks, crows and starlings, searching for the larvae. Apply Dursban WG at 1.0kg/ha if necessary.
<8 Treatment may not be needed.


Always check the Vegetable Pestwatch pages for the most recent bulletins.

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