BUTTERFLY CONSERVATION UPPER THAMES BRANCH

 

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Green Hairstreak Report 2006

 

by Tony Croft

 
Green Hairstreak
Photo © Tony Croft

 

The first reported Green Hairstreak sighting of the 2006 flight season in the Upper Thames region was on April 26 which was four days later than in 2005. The first sightings nationally were on April 21 in County Armagh and Hampshire. The final report for our region was on June 16 which was six days earlier than 2005; so a slightly shorter flight season.

 

The number of reports from observers was remarkably consistent in the mid-forties for which I am very grateful, so thank you for that.  The number of individual butterflies reported, however, was way down on 2005; only about 95 as compared with about 155.  This has to be put down to the very wet weather during the May peak.  Obviously the rain deterred people from going out to look for butterflies but did it reduce their emergence and mating?  Only time will tell. From May 14 to 28 2005 there were around 65 individuals reported.  For the same period in 2006 the number was just 10.

 

There was no discernible addition to its reported range, the Chiltern escarpment being its favoured location, but some gaps were filled in by Dave Wilton with sightings from Gavray Drive Bicester and a gentleman who called himself  “excited of High Wycombe” aka Andy Spragg who had  witnessed his first ever Green Hairstreak landing on the manure that he had just applied to his allotment!

 

I’m looking forward to this coming  season to see how the poor numbers in 2006 translate in 2007.  This is clearly a very tenacious butterfly so I live in hope.

 

As an aside I often trawl through websites of other branches to see how this species is doing elsewhere and I noticed that on the Dorset Branch website their final sighting of Green Hairstreak in 2006 was on August 5 at Canford Heath, the next previous sighting having been June 24 at Fontmell Down.  I then noticed that in 2005 their final sighting was on July 29 at Upton Heath near Poole with regular sightings back to July 9 then with a gap to June 22 . Years 2004 and 2003 were more typical of our area but 2002 had a final sighting of July 26 the previous being June 27, although the archived data for that year is very sketchy.

 

All the July and August sightings were on or near heathland leading me to surmise that perhaps in Dorset the Green Hairstreak may have two distinct flight times depending on habitat.  Otherwise the flight time in the past two years has lasted for almost three months as opposed to about two months everywhere else.

 

An alternative answer to this enigma could be that in Dorset the Green Hairstreak is occasionally double-brooded although only one book that I know of makes reference to this possibility.  All the authoritative literature states that it is single-brooded.  After consultation with Jim Asher, however, a double-brood would appear to be the more likely explanation.  I suppose that a butterfly which has such a range of habitats and food plants is bound to confound the accepted norms from time to time.

 

For information, this is the list of larval food plants for the Green Hairstreak:

 

 

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