Leatherjackets are the larvae of crane flies (Tipula spp.) (daddy longlegs). They are soil living larvae with a thick grey-brown skin, no legs and can grow up to 5 cm in length.
- Adults lay eggs between July and September in grass and cereals
- Eggs hatch 2-3 weeks later and the larvae feed in mild spells during autumn to late spring, pupating in the soil late May-June
- 90% of the time adults stay and lay eggs near to where they emerge, causing the population to continue to increase in the same field if they are not dealt with
Indicators of Leatherjackets
There are several signs that indicate the presence of leatherjackets:
- Large numbers of adult crane flies in July and August
- Feeding by rooks, crows and starlings
- Bare patches appearing in the grass
Leatherjackets feed on the roots and stems of grass plants at or below ground level.
Reseeded leys can be completely destroyed by leatherjackets.
Leatherjacket feeding not only reduces yield, but can also lead to the destruction of large areas of fields. At the economic threshold of 1 million per hectare, the weight of leatherjackets feeding below ground can be greater than the weight of livestock above ground.
Ploughing grassland in July and subsequent cultivations can destroy up to 50% of leatherjackets.