Worcestershire Record No. 22 April 2007 p. 25

Mike Williams

The Brown Hairstreak Thecla betulae butterfly is one of the county’s more enigmatic species, easier to record at its egg stage than as an adult. In Worcestershire Record Number 20, April 2006, as part of a wider article I reported that recording efforts over recent years had located the butterfly in 108 1km squares. Much of this effort is based on searching for Brown Hairstreak eggs over the winter months. Although the butterfly is still confined to east Worcestershire, its distribution is now known to be considerably wider than previously thought. Recording has continued over the last year and we have now increased the distribution in Worcestershire to 135 squares, a 20% increase in known range over the previous year (see map). Several more squares have been added very close to the Warwickshire border and we have now recorded the butterfly virtually on the outskirts of Redditch! Undoubtedly, there will be more squares to add in future years but there have been some disappointments. Following the previous article, we learned that references in the literature to eggs being found on the perimeter of a disused airfield in fact referred to the old Defford airfield and a small team of recorders from West Midlands Butterfly Conservation carried out a search of this area in February 2007. Defford is well to the south of the Brown Hairstreak’s current range and it would certainly be a real discovery to re-find the butterfly in this vicinity. Unfortunately, we were unsuccessful and suspect that this part of the county has changed considerably since the original find by former butterfly recorder for the county, Jack Green, some thirty years ago. Blackthorn is certainly nowhere near so prevalent as in the core area to the north and what we did find had been largely flailed to blazes.

A much more likely but perhaps somewhat surprising location for the butterfly is along the verge of the M5 motorway! Following the sighting of an adult near a motorway over-bridge at Oddingley in Autumn 2006, permission was sought from the Highways Agency and their local contractors Amey Mouchel to carry out an egg search adjacent to the motorway. Both organisations proved extremely co-operative and this moment of motorway madness duly occurred in March 2007. The motorway embankment between junctions 5 and 6 contains surprising amounts of blackthorn, much of it in very suitable condition, but sadly no eggs were found and locating Brown Hairstreaks on the M5 and beyond remains a challenge for next year.

West Midlands Butterfly Conservation are keen to recruit further local Hairstreak Champions to assist with recording and conservation work and if anyone is interested in finding out more please drop me an email on mike@stagborough.fsnet.co.uk A regular ebulletin is produced to keep people up to date with the latest news and developments which can be sent on request.

The maps shown above are different in format from those in Worcestershire Record 20. They have been used to show the increase in the number of 1x1 km squares in which evidence of the butterfly has been found. Despite appearances there is as yet no evidence that Brown Hairstreaks have crossed the M5 near Oddingley!