If the birds and other mammals such as Badgers and Foxes are dining out on your lawn then this is one of the reasons why your lawn might be suddenly listed on the Egon Ronay 'Good Lawn Food Guide'....
What are they after?
Chafer Beetle Larvae are the larvae of the Common Chafer Beetle or more commonly known as the May Bug that can be seen flying around on warm early summer evenings. Chafer grubs are white, comma shaped, fleshy grubs with brown heads and 3 pairs of legs on the front segments of their body. Grubs live for 1-3 years before adult beetles emerge. Patches of dead or dying grass similar to that caused by leatherjackets are caused by the grubs. Early and correct pest identification is important
When a pest problem is suspected, the turf should be examined thoroughly to find the culprit. Pests are often found first in stressed areas, such as the edges of lawns or in shady or wet areas. They are not usually distributed evenly so it is advisable to look for spots that have discoloured, stunted or distorted turf. Insects tend to proceed outward from a central point; therefore they are generally most active on the outside edge. Part the leaves of the grass and look into the thatch layer.
Go on, be brave and set about exploring in the soil beneath the grass roots…
The larvae feed on the roots of grasses during the spring and summer. They cause yellow/brown patches and, as the grasses are eaten off at the same level, it may well be that a complete carpet of turf can be removed in tact. There are usually less numerous and less troublesome than leatherjackets but their presence is usually seen the first time the lawn gets stressed by cold or drought by the frenzied activity of large birds like Crows, Rooks and Magpies. The net result – no grass roots, no grass and a lot of ripped up areas once the birds have gone! The adults and grubs have many predators: birds, badgers, moles and even foxes and these cause damage to the turf areas when they are foraging for their food.Chafer Beetle Larvae live a little deeper the root zone than Leatherjackets which reside in the upper root zone. Get your garden or pen knife out and dig below the surface to locate some, preferably in an area that adjoins an area where the birds have been pecking. If present in the soil, you will discover the larvae in a little self made hollow in the soil. The eggs are laid in soil in the late spring by the adults in batches of 10 – 30.
What do the adults look like?
The adult Cockchafer is up to 35 mm long. It has a black thorax, rusty brown wing cases and brown legs, and the tail end of the abdomen is narrowly pointed. In side view, the abdomen has saw-tooth shaped patches of white under the edges of the wing cases. The fan-like tips of the antennae are particularly obvious in this species.
There is little or any benefit renovating and repairing any damage to your lawn until you have killed the larvae. As Chafers live in the soil for up to three years you can have more than one generation in the soil at any given time. Control them by applying an insecticide as soon as you have performed a positive identification, usually in the growing season – April to September. Prevention is always better than cure so once one application has been performed, repeat annually in the if repeat outbreaks are common particularly in light sandy soil areas.
Amateur Control Measures - Visit this web link Provado Lawn Pest Killer
Professional Control Measures - Weed Free - Contract Pesticide Application Services
Pictures and part text copyright acknowledged – Bayer Environmental Science & The Royal Entomological Society.
A downloadable .PDF version Chafer Beetle Larvae is available here