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Brown Hairstreak in Worcestershire - Bulletin 10

June 2005

Dear Brown Hairstreakers,

Thanks to Terry Smith for keeping a watchful eye on our tagged Hairstreak caterpillars while I was away. The good news is that they seem to have flourished and, while on a return visit to Grafton Wood on 19th June I could only re-find two, both were fully grown at 18 mm in length. These were amongst the two smallest larvae that I had found on a previous visit, so I hope this means that the others had already made their way down to ground level to pupate. The pupal stage of the butterfly's life cycle is probably least understood of all and there appears to be little experience of finding Brown Hairstreak chrysalises in the wild. It may be like some of our blue butterflies that they are tended by ants but again no-one really knows for sure. So if you really want to make a name for yourself go find a pupa!

According to some of the literature, the caterpillars turn a rather fetching purple/pink before they descend to pupate but this, on the face of it, seems unlikely given that they have spent their entire larval stage trying to blend in to the leaves of the blackthorn. It seems much more likely that they descend first, then change colour later. Anyway, I thought some people might enjoy a picture of a 'purple cat' albeit a captive bred one courtesy of David Redhead of Upper Thames branch with again my apologies for those not on broadband. There is no doubt that there is still a lot to learn about the life cycle of the Brown Hairstreak. One clear conclusion of our larval study this year is that caterpillars do not always sit motionless on leaves during the day only becoming active at dusk as has been previously suggested. On the contrary, larvae can be surprisingly mobile during the day, moving some distances up and down the blackthorn bush at a fair pace.

The next big event on the Brown Hairstreak calendar is of course the emergence of the adult butterfly. Again, there seems little agreement over the length of the pupal stage and no doubt this is weather dependent and will vary from year to year. 2005 has all the signs at the moment of being an early season for butterflies with White Admiral, High Brown and Silver-washed Fritillary already well on the wing in the Midlands so I think around 20th July would be a good time to start looking for those elusive male Brown Hairstreaks. If you spot one please let me know. Our own branch foray (or folly as it is termed in the latest West Midlands branch newsletter) is on Sunday, 31st July meeting at Grafton Flyford Church starting at 10.30 am when we hope to search for Brown Hairstreak assembly trees. Please try to come along and bring binoculars and telescopes if you have them. The more people that turn up, the more potential territory we can cover. The following Sunday, 7th August, we shall be doing some blackthorn management in a piece of privately-owned woodland that is being specially managed for the Brown Hairstreak so also please try to support this if you can. This has become an almost annual event and is greatly enjoyed by all, especially after partaking in the lunchtime refreshments on offer!

The other Brown Hairstreak news is that we did a display last weekend in the Three Parishes Hall as part of an event aimed at drawing up a Parish Action Plan. The results of a recent public consultation were on display and it was very encouraging to see that many respondents had singled out wildlife including birds and butterflies as one of the reasons why they liked living in the area. Several respondents specifically mentioned the importance of Grafton Wood nature reserve. As a result of discussions on the day, we hope to be able to contribute a piece on local wildlife to the finished report. The support of the local community for Brown Hairstreak conservation is vital and if you know of anyone who might be interested in being added to the email list please let me have their details.

Mike Williams,
Brown Hairstreak Species Champion