This blogsite is intended primarily for use in a survey of 10 km square SK18, in the Hope Valley of Derbyshire, for evidence of the White-letter Hairstreak as part of a UK wide survey being undertaken by Butterfly Conservation (details see Links).
Information is also posted from survey visits to two other Derbyshire 10 km squares selected for the WLH Survey - SK07 and SK13: and similarly for SD 96 Yorkshire, SD 99 Yorkshire, SD64 Lancashire, SX16 Cornwall and SW23 Cornwall.
White-letter Hairstreak Butterfly Survey Procedures
Preliminary procedures involved finding elms occuring in the square, since these are the principal food plant of the butterfly's caterpillars. These are then periodically visited looking for WLH eggs, lavae pupae and eventually butterflies (in the flight period mid June- Mid August). Progress with SK18 The survey of the 10km square continues in 2008, but so far no evidence of WLH has been seen this year. No WLH butterflies have been seen so far (including on the tree where they were seen last year) although the flight period started in nearby counties at the beginning of July. In 2007, WLH butterflies were found in the SK18 10 km square at Castleton and a pupae at Hope. Although elms were found in the target km square SK12 83 and its associated tetrad, they are generally in exposed situations at relatively high altitude. No evidence of WLH has been found in them so far. So far, attention has focused on the target kilometre square SK12 83 which covers the Mam Tor area. The secondary search has concentrated on those km squares which are close to it: in particularly, those of the 2km square in which it occurs and those in the vicinities of Castleton, Edale and Hope; see items in the the Blog for elm and WLH findings; photos of some of the elm trees found so far can be seen in Photos section together with some notes. Although prior to this survey there were no records of WLH sightings for this 10km square, we have already had some success. A pupa has been found on an elm near Hope and the butterflies have been seen "spinning" by a large elm in the middle of Castleton (details see blog).This brings SK18 to status "WLH found in 10 km square". So far, no WLH eggs, lavae or pupae have been found in the target 1km and 2 km squares. This far north in the country, the distribution of the WLH is highly dependant on altitude. In Yorkshire, for instance, WLH are rarely reported above 200 metres. Butterfly Conservation have asked us to continue surveying the 10km square to establish find at what altitude WLH are no longer found. Help in surveying the remnant of the one hundred 1 km squares in the SK18 10km square for both elms and WLH would be much appreciated. Whilst the flight period of the butterfly occurs in July and early August, survey activity continues after that, looking for WLH eggs. These can be found most easily in the late autumn and winter, when the leaves have fallen from the elm branches on which they are laid. If you wish to get involved, contact me, Rob, on robinsects@yahoo.co.uk. Progress with other squares The only square which has been given particular attention is another in the local local area - SK07 in the Buxton area of Derbyshire. WLH butterflies have been seen by the Wye Bridge in Buxton (see Blog item). Again, this is the first reporting of WLH for this 10km square. Other squares have only had rapid cursary surveys, looking mostly for elms in the target 1km and 2km squares. They were surveyed merely because I happened to be in the area and noted that at these squares appeared not been previuosly looked at. It is hope that the information provided will be of help to anyone who should take on surveying of these 10 km squares in detail. There is no intention, on my part, to make repeat visits. Rob Foster
