Brown Hairstreak Bulletin - Issue 103

Dear Brownhairstreakers,
Once blackthorn begins to flower it becomes very difficult to spot Brown Hairstreak eggs but, this year, the late Spring has meant that the egging season lasted well into April rather than finish at the end of March as normal.  Indeed, the final foray by the Thursday Streakers on 11th April produced a combined count of over a 100 eggs from sites near Bradley Green and Feckenham which was pretty amazing and one of our highest individual daily counts of the entire season.  The tally included a very fine triple egg cluster photographed by Simon Primrose.  The large numbers found at Bradley Green, in particular, suggests an assembly tree in this vicinity and this is something we hope to follow up as part of this year's Big Ash Bash.  This will be the third year of our study into Brown Hairstreak assembly trees and we are still looking for further volunteers to help with this.  Martyn Ganderton at Stock Green has noticed that his garden tree, which has attracted Brown Hairstreaks for many years, comes into leaf later than other nearby ashes which is a feature worth checking out on our other known trees.  Back in March, Simon Primrose and Jenny Tonry received permission from the owner to search an a small field near the assembly tree at Cowsden which produced well over 20 eggs with others nearby.  Over at Shurnock (another assembly tree site), renewed efforts by Gill and Geoff Thompson, along with Simon Primrose, pushed the egg score there over the 300 mark which, although down by around 25% on the previous year, was still an impressive total.  An interesting observation here was that 55% of this season's eggs were laid on the highest part of the site which is certainly difficult to explain as generally the Brown Hairstreak favours more sheltered habitats.  When you add to this, the 600+ recorded around Grafton Wood, plus the many others recorded elsewhere and catalogued in previous issues of the eBulletin, the final figure for the season is well into four figures and this, of course, is only a tiny fraction of the total egglay in Worcs.  Hopefully, a reasonable percentage of these eggs will have survived the winter and will begin to hatch out within the next few days.  Geoff Thompson found the first "hatchling" at Shurnock on 1st May but clearly emergence is late this year as out of a sample of 12 eggs examined at Bradley Green yesterday I found only one so far hatched.  All of this, sadly, does not mean that Worcs will be swarming with Brown Hairstreaks come August as research suggests that up to 80% of caterpillars are found and killed by predators.  According to Jeremy Thomas, harvestmen, spiders and other insects are the main culprits in the first month and, after this, as they grow larger, it is the turn of insectivorous birds.
With so many natural enemies, good hedgerow management is key to maintaining Worcs' Brown Hairstreak population and we continue to work with local landowners and other conservation organisations as part of our Hedgerows for Hairstreaks initiative to encourage this.  We are always keen to find novel ways of getting across our message to the wider public and this spring we have produced, in conjunction with a local farmshop, a Sloe Jelly which is now on sale.  The sloes were picked last autumn, mainly by the Thursday Streakers, and have been mixed with sloe gin, apples and damsons to make a delicious jam.  Hairstreak Jelly is on sale at the Wayside Farm Shop in Wickhamford ( tel. 01386 830546) midway between Evesham  and Broadway and we are grateful to the owner Elspeth Robertson for her support.  Each jar sold has a Brown Hairstreak sticker on the lid and a tie-on label explaining that less intensive hedgerow management saves money, is good for wildlife and produces more sloes!  The Hairstreak Jelly can be obtained direct from the Farm Shop at £3.75 a jar or at events attended over the summer by West Midlands Butterfly Conservation beginning with the Tiddesley Wood Open Day this coming Sunday, 5th May.  Only limited stock is available so it is definitely a case of first come first served.  All profits from the sale of the Hairstreak Jelly is being donated to West Midlands Butterfly Conservation. 
Butterfly Conservation nationally has recently produced an update of its Brown Hairstreak factsheet which can be downloaded from the national website  The factsheet emphasises the importance of blackthorn suckers to the Brown Hairstreak and the need for rotational management of hedgerows.  It also advocates the cutting of known breeding hedges in August which is something that we have tried to encourage here in Worcs with some excellent results.  It is also good to see reference to avoiding the use of chemicals on field margins which is particularly topical given the recent EU ban on neonicotinoids, a group of insecticides which have been implicated in the decline in bee populations; a ban sadly not supported by the UK government.
The main event of the Worcs Brownhairstreaker's year is of course the annual open day at Grafton Wood which this year takes place on the Sunday of the Bank Holiday weekend, 25th August at the Three Parishes Hall in Grafton Flyford 11 am - 3 pm.  The event for the second year forms part of the Pershore Plum Festival ( and more details will be available nearer the time.  The Hairstreak Trail which was initially mentioned in eBulletin 93 nears completion and hopefully will be ready in time for this year's open day.
Mike Williams,
Brown Hairstreak Species Champion,
West Midlands Butterfly Conservation