Help the Forestry Commission and look out for a new insect pest this summer

Oriental chestnut gall wasp (Dryocosmus kuriphilus) is an insect pest of sweet chestnut trees which was first found in Britain in June at a site in Kent. 

Oriental chestnut gall wasp (OCGW) poses a serious threat to our sweet chestnut trees and the Forestry Commission are taking eradication and containment action to control the outbreak.  They are also conducting intensive surveillance to check if the pest has spread further.
 
 

The Forestry Commission have asked if people completing OPAL tree health surveys this summer can look out for OCGW. Don’t worry, the wasp does not sting or pose any other risk to human health. 
 
You can refer to the Forestry Commission website for full information, including a symptoms guide which you can print or download onto your mobile phone or tablet www.forestry.gov.uk/gallwasp . 
 
What to look for:  The most obvious symptoms are green or rose-coloured galls on leaves, which can grow to 4cm in diameter.  You are unlikely to see the tiny wasps, which are less than 3mm long (see photo above for reference).
 
What to do if you think you have spotted the pest:
1.  Check that it is a sweet chestnut tree – refer to the OPAL tree health guide to distinguish between sweet chestnut and horse chestnut.  The Forestry Commission do not need reports of galls on other trees.
2. Check the symptoms – it is green or rose-coloured galls on leaves which are characteristic of CCGW.
3. If possible, take a clear well-lit photograph.
4.  Note the precise location of the tree/s e.g.  a 10-digit Ordnance Survey grid reference; full address, including the full postcode; and/or precise instructions for finding the tree/s, e.g. “35 metres north-west of the park entrance in XXX Street”.
5. Contact the Forestry Commission preferably by sending an e-mail to: tree_health_england@forestry.gsi.gov.uk ; or telephone  0300 067 4000.  Please provide a daytime telephone number where the Forestry Commission can reach you to clarify any points.