BACK__________________________________________________________________________________________________

Brown Hairstreak in Worcestershire - Bulletin 42

April 2007

Dear Brownhairstreakers,

Meet Billy, the Brown Hairstreak caterpillar, discovered and photographed by Les Clarke on 26th April.  Billy is the second larva to be spotted this year and joins Alison, who I recorded on 22nd.  Compared to last year these dates are very early for finding caterpillars and are a reflection of the warm and advanced spring.  We tagged far more eggs last winter and this undoubtedly helped enormously on 22nd when I managed to locate 58 eggs in total of which all but eight had already hatched.  It is easy to spot eggs that have hatched from the usually neat exit hole in the centre, best seen with the aid of a magnifying glass.  Eggshells are not eaten as in some other species and remain in situ on the twig.  This count compares with the equivalent weekend last year, which was the Grafton Wood open day, when we were unable to find a single hatched egg.  Finding larvae as always proved difficult and I suspect most were still within the unfurling leaves of the blackthorn where the tiny caterpillars burrow on emerging from their egg.  Alison was the smallest caterpillar I have found, no more than 3mm long but still extremely active.  We shall be trying to follow the fortunes of Alison, Billy and friends over the coming weeks and help with this will be welcomed.  Caterpillars can be found generally on the underneath side of blackthorn leaves but occasionally you may spot them making their way along the stem.  We are having an official caterpillar hunt on 20th May, meeting at Grafton Flyford Church at 10.00 am and we hope that some of our local champions will want to join in.  Caterpillars should hopefully be easier to spot by then as they will be a reasonable size.  We may also find larvae of various moths to provide a little variety.  Everyone finding a caterpillar gets to have the honour of giving it a name!  While at one level this seems a little odd (and probably is), the naming of caterpillars does have a serious side as it enables us to follow the development of an individual caterpillar and learn more about the life history of this fascinating insect.  One thing we would like to find out more about is the relationship (if any) between Brown Hairstreak caterpillars and ants and we would be very interested in hearing of any observations people might make.  Many butterflies in the same family as the Brown Hairstreak have a very close relationship with different species of ant but detailed observations are often lacking.  Last year, one of our caterpillars (Deborah), when virtually fully grown, was apparently "attended" by an ant and it would be interesting to know whether this is typical behaviour.  Some of the literature refers to Brown Hairstreak pupae possibly being buried by ants but nobody is clear about the processes leading up to this.  We would also be keen to find out which particular species of ant might be involved and if any ants seen could be collected for future examination that would be helpful.

Like last year, we have a number of Brown Hairstreak events planned for the summer.  Apart from the caterpillar hunt, we have a day planned on 5th August to search for male Brown Hairstreaks which always proves a challenge but can be very rewarding and then, on 2nd September, is our annual Brown Hairstreak day when we will offering a guided walk to see egglaying Brown Hairstreaks, followed by refreshments in the village hall.  Also on 12th August, we shall be having our yearly 'Blackthorn Bash' at Bob Steele's wood followed by a walk around the site in search of Brown Hairstreaks.  Finally and before all of this, is Butterflies, Bugs and Botany Day at Grafton Wood on 22nd July which is a brand new event organised as part of national Save our Butterflies week.  Please make a note of all these events now, more details will be provided nearer the date.  So far this has proved an exceptional year for many species of butterflies which have been recorded well ahead of their normal emergence times.  Common Blues, for example, which are usually not seen before mid-May sometimes later, were seen before the end of April and it will be interesting to see what impact this might have on species that fly later in the year like the Brown Hairstreak.  We will perhaps get a better idea on the caterpillar day as we will be able to compare the size of larvae found with those on similar dates in previous years.

As always, please email me with any Brown Hairstreak related news.  Otherwise hope to meet many of you on 20th.

Mike Williams,

Brown Hairstreak Species Champion