Above:- Adult Horse Chestnut Leaf Miner (Cameraria ohridella)

Cameraria ohridella was only discovered near Macedonia in 1985. It was originally discovered in Greece in the 1970's, but not recognised as a separate species until 1985. It then spread rapidly to other European countries, before reaching the UK (at Wimbledon, south-west London) in 2002, but was considered likely to have arrived the previous year, due to the number of mines found.

Accidental transportation via either road or rail, was thought to be a contributing factor in helping the moth reach the UK. Since 2002, it has been found over much of the south-east UK, reaching the neighbouring county of Leicestershire in 2005. The moth has already reached Derbyshire.

We are inclined to believe that this moth may have become established in southern areas of Nottinghamshire during 2006.

The long-term threat by C. ohridella infestation, to one of our most easily recognised trees is not fully understood and the moth's rapid colonisation of the UK, is being closely monitored by the Forestry Commision. Current evidence suggests that there is no decline in tree health and that trees are capable of producing new growth later in the year. Trees seem to survive repeated infestations OK and the damage is largely cosmetic (there can be hundreds of mines per leaf) Most damage occurs too late in the growing season to adversely affect the tree anyway.

The Forestry Commision is not operating a felling policy at this time and is unlikely too in the near future at least.

After weeks of searching at varous sites, we finally discovered several occupied mines on a Horse Chestnut in the grounds of Nettleworth Manor near Mansfield Woodhouse on July 9th 2007. The mines all seemed to be below a height of about 2 metres. Following checks with other UK entomologists, it was revealed that there were in fact, no known (or reported) records of this invasive moth for the county to date.

We made a better count of the number of mines present the following morning, reaching around 15/20 mines on the two Horse Chestnuts present. Further searches have been conducted and we found an increasing numbers of mines on three other trees nearby. Most of the mines found so far, have been found on foliage growing in sheltered locations, often well under the tree canopy and in shade. Side shoots from the trunk are also affected.

Confirmed locations/records of the Horse Chestnut Leaf Miner in 2007

Low-level infestation ... Within just a few days of the original discovery, mines were found at Attenborough and in the Mapperley, Daybrook and Arnold areas of Nottingham. It is possible that the moth may have been noted in Wollaton Park during 2006, but no supporting evidence was produced and the record cannot be verified. In the north of the county, more mines were quickly found at both Carburton and two sites in central Worksop. The moth is also well represented from the Southwell area and was finally found at Eakring on July 18th. The moth is obviously extremely widespread throughout Nottinghamshire, but currently at a fairly low infestation rate from the evidence produced to date.

At the end of July, trees with a considerably higher rate of infestation were found in Caunton, where the number of mines per leaf ranged from a single mine to well over 25 on many leaves. On many leaves, the surface area was affected by about 60-75%.

Right:- Three leaves showing different levels of C. ohridella infestation. The middle leaf is currently fairly typical of those found at most of the sites surveyed to date (July 31st 2007) but the leaf on the far right is from Caunton, which has the highest level of infestation found so far.

Of the locations checked in 2007, trees at Oxton and Caunton had much higher levels of C. ohridella infestation than anywhere else. But it was believed at the time, that many south-east Nottinghamshire sites would have shown infestations of similar levels. An appeal at the time for records from this part of the county proved to be unsuccessful, so this was never confirmed.

A year on and a return visit to Caunton in mid-September, showed just how quickly infestation levels have increased. Large proportions of the same trees, were now almost devoid of any green leaf area following a succession of broods throughout the year.

Right :- Cameraria ohridella mines on Horse Chestnut at Caunton in 2007. Below left :- A wider view of the same Horse Chestnut tree in September 2008, showing the huge number of Cameraria ohridella mines now present. Below right :- Close up showing the typical amount of affected leaf area.

We are still willing to recieve and collate all further records of C. ohridella in Nottinghamshire for passing on to the county micromoth recorder and other organisations. Records are needed from the following areas of the county. Bingham, Radcliffe-on Trent, Cotgrave, suburban areas east, south-east, south, south-west and north-west of Nottingham, Retford, Worksop and most of north Notts, Tuxford, Newark, Mansfield, Sutton-in-Ashfield, Kirkby-in-Ashfield and Hucknall.

Please e-mail any records and/or photographs to the address below, quoting a grid reference, date and an estimate of the number of mines present (either total or per leaf) etc. E-mail any records to us at Eakringbirds.com

The following people have contributed sightings and further records from around the county -..RJ ..Rob Johnson; .DP ..Dilys Pendleton; TP ..Trevor Pendleton; .RR...Richard Rogers.