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Brown Hairstreak in Worcestershire - Bulletin 9

June 2005

Dear Brown Hairstreakers,

I thought I'd get in another quick bulletin before I shoot off to Greece next week. Managed to get over to Grafton Wood again on the Bank Holiday Monday and I am pleased to report a growing family of Brown Hairstreak caterpillars. In fact, growing in both senses of the word: most of the larvae have put on an extra couple of millimetres over the past week and are now all between 8-11 mm in length; and I managed to find another 5 caterpillars all within the same three areas of the wood. Out of the three original larvae found the previous weekend, I managed to relocate two.

Both had moved some considerable distance from where I had seen them last, although still on the same blackthorn plant. Certainly at this stage (just over half grown), the caterpillars appear very mobile. I found another larva on the rampage rather similar to the one I photographed last week which moved around 6 cm down the main stem of the blackthorn in the ten minutes I kept it under view. Indeed, on returning an hour later it had moved a further 4 cms or so along a side shoot where it was sitting rather nonchalantly under a leaf not far away from where I had first located it on my previous visit and trying to pretend it had been there all morning! Whether these daytime wandering caterpillars are the exception to the rule or the norm is open to debate and it would be interesting to examine this in more detail. The additional caterpillars were generally on blackthorns which I am pretty sure I had searched the previous week so I guess my ability to find them must be improving.

One observation was that most of the larvae I found were between 4-6 foot above ground level which is considerably higher than the height that the majority of eggs are laid and there was a tendency for caterpillars to be towards the tip of the individual blackthorn plant. This could of course just be observer bias as it is much easier to search blackthorn at nearer to eye level but it would be interesting to compare notes on this with our Upper Thames branch colleagues.

One question of course is who is going to keep an eye on all this caterpillar action while I am away and if you are interested in taking this on for the next two weeks please get in touch. Hopefully I have now managed to mark the caterpillars in a way that makes it easier to find them, although this could be wishful thinking. If you do visit the wood keep an ear open for Nightingales - the exciting news of the past week was of a report of a singing male which was the first for the wood in almost thirty years.

Best Wishes,

Mike Williams,
Brown Hairstreak Species Champion