These are the grubs of the common crane fly or 'daddy long legs'. They cause severe damage to turf areas over the autumn to spring period when they are feeding on the grass roots. The effects are most noticeable during dry spring weather when the turf starts to die off due to an inadequate root mass, which cannot provide adequate water and nutrients to the plant.
There are several signs that indicate the presence of leather jackets:
- A large number of adult crane flies in July and August
- Rooks, Crows and Starlings feeding on the lawn
- Bare patches appearing in the grass
- Yellow patches in early spring
Chafer grubs are the larvae of the chafer beetle. They cause problems on lawns by feeding on the roots of grass plants.
The adults appear between May and July depending on the weather conditions in spring, they feed on shrubs and trees before laying the eggs in the grass.
Larvae hatch about 2 weeks later and begin to feed on grass roots until late September when they move deeper into the soil where they pass the winter. The larvae have white bodies curved in letter C shape, light brown heads, with 3 pairs of legs.
As the larvae grow bigger, they cause more damage. Early symptoms include gradual thinning, yellowing and weakening of the grass where the roots have been damaged followed by the appearance of irregular dead patches. In most cases the larvae are discovered when birds or mammals begin to rip up areas of the turf looking for the grubs.
Frit Fly occurs in almost all grasses in the UK. They produce small (about 5mm long) yellowy white larvae that bore into the centre shoot causing loss of tillers. The plant isn’t killed but is stunted and grows poorly. The individual larvae can move and attack other tillers and other plants.
Biological Control of lawn pests.
With the removal of chemical insecticides to control insect pests in lawns, we have to rely on biological controls called nematodes. These are microscopic worm-like multicellular animals, some are beneficial to us and some are not. The beneficial ones either kill the target pest or as in the case of ants, cause them to move their nest. They are generally applied as a drench to the lawn surface where they move through the soil to find their target. Once watered into the lawn, they will need to be “cared for” until they have found their target. This usually requires the lawn to be kept moist by watering so that the nematodes can move through the soil.
In comparison to chemical controls, I have found them to be very much more expensive, and if the care instruction not followed, very much less effective.
The home owner is now faced with two choices, use the nematodes and do the required work to ensure they are effective, or, allow nature to take its course and then repair the damaged caused after the attack. It’s not possible to calculate which method is the cheapest, as the damage can be from a small patch, out to large areas of ripped up and damaged turf.