BIOLOGICAL CONTROL OF LEATHERJACKETS WITH NEMATODES
The leatherjacket, also called tailor or stilt mosquito, belongs to the family of gnats (lat. Tipulidae) within the suborder of mosquitoes. Leatherjackets have a mosquito-like appearance, are 16-25 mm in size and brownish in color with conspicuously long legs. They fly from mid-August/early September to early October.
After flying, leatherjackets lay their eggs in the ground.
From about mid-September, the larvae hatch and pass through four larval stages: L1 and L2 feed mainly at night on above-ground plant parts, L3 overwinters in the soil below the frost line, and L3 and L4 feed during the day just below the turf in spring. From mid-May, feeding activity of L4 larvae decreases. They pupate in the soil to begin their flight as leatherjackets in mid-August/early September, completing the development cycle.
Damage caused by leatherjackets
The leatherjacket itself is harmless, it does not sting or eat plants. The only damage is caused by the meadow snake larvae in the L3 and L4 stages, which become visible under the lawn in spring. They are gray, legless, barrel-shaped, elongated about 4 cm long and can be easily distinguished from hair gnat larvae by the so-called "devil's grimace" at the anus. Their English name "leatherjacket" is derived from their appearance, it really seems as if they wear leather jackets.
Starting in spring, the L3 and L4 larvae feed just below the turf. This makes them an easy target for crows and other birds. Their pecking also damages the turf.
Meadow snail larvae cause the most damage in spring and early summer. The typical damage pattern is bare patches in the lawn in nests and holes caused by pecking birds.
Control leatherjacket larvae with nematodes.
Control of leatherjacket must take place in the fall, even though no damage is yet visible, because only the young larvae in the 1st larval stage (September/October) are susceptible to nematodes. Damage will not be visible until spring when the L3 and L4 larvae are feeding just below the turf. By then, however, it is already too late to use nematodes.
Our product nemastar® contains nematodes of the species Steinernema carpocapsae. This species specializes in meadow and cabbage snails, among others, and can use them for its own feeding and reproduction. The effectiveness is 80% if nemastar® is applied approx. two weeks after the peak of the snails' flight. The meadow snake larvae are then 1 -2 cm below the surface.
The nematodes are supplied alive in a powder. For application, they should be mixed with water exactly according to package instructions and applied to the affected areas.