Leather Jackets

If your grass is growing poorly or thinning in small patches during the months of March-May, you may have a problem with leatherjackets.

Starlings actively pecking in the turf are another sign of leatherjacket attack.

Leatherjackets are the larval stage of the crane fly or daddy long legs. The Leatherjackets start to feed on grass roots in the autumn. They will continue to feed through the winter and spring.

In the summer the Leatherjackets pupate, then emerge in August and start to lay their eggs back in the infected lawns.

Leatherjacket larvae are about 2.5cm / 1" long, greyish black in colour, legless and with no distinct head.

The young start to feed immediately after hatching, and as already mentioned will continue to feed throughout the winter, ready to gorge on grass roots in the spring.

In general, they stay underground in the day and move up to the turf leaves in the night. They are very sensitive to drying, and do not survive if they are dried out when heated up by the sun. On very cloudy days when the turf is wet, you can see the larvae in the turf.

Check the thinning areas in your lawn early in the morning when the grass is wet for the presence of the leathery, brown maggots, and look out for "Daddy Long Legs", flying near your turf or gathering on walls.

The symptoms of both Leatherjackets and Garden Chafer Grubs are the same :

• Grass growth slows and yellow patches appear.
• Grass is easily pulled up, with little or no root growth.
• Starlings peck at the grass in an attempt to eat the grubs.

To cure the problem:

The time to control the insects is when they are maggots, not flies. When you see them on the walls or flying about, it is generally ineffective to kill them with insect spray.

Therefore, when you see damage, and you have identified larvae feeding on your turf in the night or early morning, you should try and control them.

Water your lawn lightly in the evening. Cover it with black polythene sheeting. The larvae will be attracted to the wet, dark surface. In the early morning, remove the black polythene sheet. Many of the larvae will be caught on the surface. You can let the birds do the removal job for you or rake them off.

Or go to the opposite extreme. When the maggots are feeding in your turf, water your turf less. The turf can be dried out quite a bit before it will suffer, but the maggots need to be wet to survive.

Insecticides are also available for the control of leatherjackets. Water in an insecticide containing HCH in autumn or use a product based on leatherjacket killing nematodes in spring.