Proprietary products are also available to ensure that ewes get adequate magnesium. Excess magnesium is unnecessary and may cause scouring. Grassland Management Leatherjackets Leatherjacket populations are very high this spring causing significant damage to grass swards. The larvae of the crane fly feeds just below the surface of the soil destroying the roots and the underground stems of grass causing the plant to die. If large dead patches are appearing in pasture, examine just below the surface of the soil to confirm identification.
Leatherjackets lack a distinct head and are completely legless.
They do not curl around when touched. Bibionid larvae are often mistaken for leatherjackets but they have a distinct black head and are of minor importance. Sprays containing chlorpyrifos such as 'Dursban' or 'Spannit' give good control for leatherjackets.