Crane flies
feed voraciously when the soil begins to warm up in spring. The larvae pupate below the soil surface in summer. The pupal stage lasts about two weeks. [...] General The larvae of crane flies , called leatherjackets, live in the soil and feed on roots and shoots (which they pull into the ground of mainly grasses [...] Eggs are black in colour, oval, 1mm long and deposited on the soil surface. Larvae are cylindrical, tapering toward the head, and grey-brown in colour.