Worcestershire Record No. 21 April 2007 p. 13

THE HORSE CHESTNUT LEAF MINER (CAMERARIA OHRIDELLA) IN SW WORCESTERSHIRE

Robert Homan

The Horse Chestnut leaf miner Cameraria ohridella is an extraordinary moth. It was first recorded in the UK in 2002 (1) and has since spread throughout southern England to such an extent that it is now one of the most common leaf miners in the region. The insect was first recorded in Gloucestershire in 2005 and is now well established and widespread in that county (2). It has been recorded in small numbers in Horse Chestnuts in south west Worcestershire in the autumn of 2006 and the number of mines and their size, which is indicative of late summer and autumn generations, suggests that this region currently marks a frontier of spread. The distribution pattern up to mid-October 2006 is shown in Fig 1.

The distribution of Cameraria ohridella in SW Worcestershire, 2006, by monad  Leaf mine of Cameraria ohridella (left)and fungal blotch of Guignardia aesculi (right), Kemerton, September 2006

The results here are only tentative as the mines are difficult to see in the early stages of colonisation and can be overlooked among the very common fungal blotches created by Guignardia aesculi.  Kinsham Lane has a very large population of the insect and it could be that the moth is in its second year at that location. By contrast the records from the two monads at nearby Overbury consist of single mines only.

The moth has also been recorded at Upton upon Severn and at Barnard’s Green, Malvern. In the latter case, colonisation is certainly at an early stage with just four mines being located in a chestnut near the shopping centre, but none on the trees towards Malvern railway station or in Great Malvern itself.

By the time you read this, the information could be out of date, such is the rapidity of the insect’s spread. Certainly in 2007 Cameraria will be an easily found addition to Worcestershire’s insect fauna. Whether it is a welcome addition depends on the credence you wish to give to reports in the press about the potential impact of the moth on the UK’s Horse Chestnuts.

References:

“Horse chestnut leaf miner - Cameraria ohridella” - http://www.forestresearch.gov.uk/website/forestresearch.nsf/ByUnique/INFD-68JJRC
GAUNT, ROGER “Gloucestershire Moth Report 2005”, in The Gloucestershire Naturalist, No 17, June 2006.

Further note 30.10.06
As I suggested the information above IS out of date - I have found mines in Bushley and Broadway. Coincidentally there is a front page article in the Cheltenham Echo today all about "killer moths" and their potential to destroy chestnuts in Cheltenham's Promenade.

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