Leatherjackets are the larvae of crane fly (daddy longs legs). Adults typically emerge in late July to the end of September early October, depending on the weather conditions.
Crane fly will begin to lay eggs almost immediately, depositing up to 400 eggs. These then hatch after approximately 14 days , this is when the larvae begin to feed on organic matter and roots.
The adult crane flies resemble a large mosquito and usually appear in late July till October. They have a short life expectancy of less than 14 days, but the larvae that hatch from the eggs laid around this time can create havoc in your grassland.
Feeding starts again the following spring and they gorge on grass roots before pupating to emerge as adults in August.
The symptoms include :-
· Grass growth slows and yellow patches appear.
· Grass easily pulled up with little or no root growth.
· Birds, particularly starlings, will pull at the grass in search of the leatherjackets.
Bacillus thuringiensis var . israelensis (Bti) has also been suggested as a promising biological control agent (Evans, 1996). Autumn application of Bti to grassland in Scotland reduced the leather jacket population from 3 million larvae ha-1 to 0.5 million larvae ha-1. This reduction was similar to chlorpyrifos applied at the recommended rate.
Taken from a paper published in the Sports Turf Research Institute's annual "Journal of Turfgrass and Sports Surface Science", Vol 80,