Cockchafer

The grub of the Cockchafer Beetle is a particular pest of grassland, cereals and new gardens that have been created over previous grassland. The grub lives in the soil for three or four years, moving near to the surface in the late summer. There are both biological and chemical controls available below.

Your Questions Answered

Q.
What are the habits of the full grown beetles?

Fully grown chafer beetles feed on the leaves of trees and plants but do not do much damage and the adult is not considered to be a pest. They are mostly active at night. It is the grub stage of the lifecycle that does the damage by feeding on the root system of plants.

Q.
Will dousing the lawn with the appropriate pesticide kill current and future generations or just the current one?

If you decide to use a pesticide on your lawn, then I believe this should eliminate this years infestation of chafer grubs: Provado Lawn Grub Killer, the active ingredient is: imidacloprid

Otherwise you could use a natural pest control from this company: http://www.angliangardener.co.uk/green_up_your_fingers/pest_diseases/chafer_beetle_larvae.htm

Q.
Should I worry if I have cockchafer grubs in my grass, will they do any long term harm.

Chafer grubs are a pest as they are root feeders and will cause large brown patches on your lawn especially as the ground dries out. They also can do serious damage to flowers and vegetables. Starlings, magpies and crows may also make a mess of your lawn as they dig them up. However they are harmless to humans as are the resultant beetles. If you only have a few I would be tempted to leave them alone. They tend to succumb to dry conditions so if this year's summer ever materialises the dry ground conditions will control them. The chemical imidacloprid will kill common chafer grubs but is not effective against the leathery skins of the cockchafer. Also it is highly toxic to other wildlife. If you would like to get rid of them, give the heterorhabditis nematode a try. They are natural aggressive organisms that you water into the ground and kill the grub by getting inside and releasing bacteria that prevent the grub from feeding. We don't stock them but they are available online

Q.
how to stop grubs in pots?

A soil insecticide that contains imidacloprid should do the trick. Bayer do a range, I believe the product line Merit or Premise is quite easy to get hold of in garden centres