25 March 2013
Chafer Grubs are the larvae of the Chafer Beetle. The grubs cause damage to lawns as they feed on the roots of grass. This can cause the grass to yellow as the water and nutrient uptake of the plant is reduced. But more visible is the secondary damage caused by birds when they dig up the grass to feed on the grubs.
Chafers have a 3 year life cycle. In practical terms this means that the insecticide we apply one season, (as part of an on-going control programme which has been running for seven years) does not immediately control the damaging bugs, but actually controls their numbers for following seasons.
This year the damage from the bugs is particularly bad because the chemical application we made in late spring/early summer 2011 was done in less than ideal conditions and was therefore less effective. The chemical must be washed into thoroughly moistened soil as swiftly as possible, as it degrades in UV light, and as such should ideally be applied in damp conditions. However in 2011 the chemical was applied on a day when rain was forecast, but unfortunately it never came.
The damage caused was most apparent in the Fellows Garden and it was decided that re-turfing was the best option for this area. The damaged turf was removed and new turf was laid in February. The lawn has just had its first mow of the year and is already looking good, and we have our two fake hawks (Ethel and Ernest) soaring majestically at the dizzy height of two metres, to discourage other birds from attempting to seek out any more Chafer Grubs.
In Latham and Front Court we decided to re-seed the patches of lawn which had been affected. This involved raking the bare soil to create a suitable seed bed, seeding the area, then covering the seed with a layer of loam to improve germination rates and reduce the likelihood of birds feeding on the seed. All we need to do now is to eagerly await the onset of a warm spring, allowing the new grass to flourish!