Plea for public help in tracking down rare UK butterfly

Only one colony of brown hairstreaks in the Midlands
July 2010: Conservationists in the Midlands are calling on the public to help expand the area's only colony of the brown hairstreak butterfly. The nationally rare butterfly favours ash trees, and the Worcesterhire Wildlife Trust would like to hear not only of sightings of the butterfly itself in the area, but also wants information about any trees that may be a suitable habitat. As part of conservation effort, a Brown Hairstreak Day will be held next month when the females are likely to be looking for nesting spots.

RARE SIGHT: The male brownstreak buttefly, which flies among tree canopies. Picture: Robert Wasley

Grafton Wood near Grafton Flyford, about half way between Worcester and Stratford-upon-Avon, is jointly owned by Worcestershire Wildlife Trust and Butterfly Conservation and is the centre of the one Midland colony of brown hairstreaks. In recent years, the colony has spread to surrounding woodlands and hedgerows including Trench Wood, Feckenham Wylde Moor and Humpy Meadow. People in the area are now being asked to keep a lookout for ash trees that are being used by the adults.

Males are rarely seen
brown hairstreaks will be on the wing at the end of this month and fly in the canopies of trees – so they are rarely seen by most people. Females are most frequently seen as they descend to hedgerows in late August and September looking for suitable egg-laying spots. The butterflies often congregate on trees known as assembly or master trees, usually ash, to feed on aphid honeydew although they're occasionally found lower down feeding on common fleabane and bramble.

Mike Williams, West Midlands Butterfly Conservation Species Champion, explained: ‘Numbers of brown hairstreaks have increased over the past few years - but we need help in identifying and recording their colonies.

‘In particular, we'd like to know of any ash trees that are being used by the adults. It can be difficult to see the butterflies as they tend to stick to the canopies of trees - but they do occasionally descend and it may be that some people have noticed butterflies flying around an ash tree from their upstairs windows. The size of the tree doesn't seem to be particularly important but they do tend to be prominent - often on the edge of woodland or in hedgerows.

‘The butterflies are best spotted early in the morning, before 9am, on warm sunny days.'

Residents in the Grafton Flyford, Stock Green and Cowsden areas in particular should keep a lookout as populations of brown hairstreaks are already known there, although the locations of only a handful of assembly trees are recorded.

James Hitchcock, Conservation Officer for Worcestershire Wildlife Trust, said: ‘It's really great that our population of brown hairstreaks in the area is expanding. Both the Wildlife Trust and Butterfly Conservation are working hard on our nature reserves and with local landowners to help ensure there is suitable habitat for the butterflies to expand their range.'

The two charities organise an annual Brown Hairstreak Day at the end of August to look for the female butterflies who descend to lay their eggs. This year's event takes place on Sunday, August 29. Those wishing to take part should call John Tilt on 01386 792458.

The trust would like to hear of sightings of brown hairstreak butterflies, as well as details of any ash trees that may be suitable for the colony. Contact Mike Williams on 07802 274552 with information about the brown hairstreak that may be of interest.