White-letter Hairstreak

Scientific Name - Satyrium w-album

Flight Period - June to August

Overwinters as - Egg

Habitat - Hedgerows, woodland

Larval foodplants - Elm

Conservation status - Section 41 NERC species of principle importance, UK BAP priority species, BC Priority high

Northamptonshire distribution - Localised and declining

Best public sites to see them - Brackmills Industrial Estate, Fermyn Woods, Finedon Pocket Park, Fineshade Woods

The White-letter Hairstreak, while widespread in the county, has suffered serious declines in the last few years. This is chiefly due to the ravages of Dutch Elm Disease on its larval foodplants of Elm trees. Many large areas of Elm have succumbed to this disease and locations that used to hold large colonies are now sadly gone. Fortunately, this butterfly does seem to be able to colonise new areas and each year more dots are added to the distribution map as new colonies are found. The butterfly is very similar to the Black Hairstreak but the hindwing lacks the row of black spots and the white streak forms a distinctive “W” mark, hence why it is called the “White-letter”. The White-letter Hairstreak is becoming quite uncommon in the county but its distribution still remains widespread and any Elm will be worth checking for them. However, the best sites to see them are Brackmills Industrial Estate, Fermyn Woods, Finedon Pocket Park and Fineshade Woods. For more information about how to identify the Hairstreaks please click here.

White-letter Hairstreak Distribution 2018 - 2022

White-letter Hairstreak

White-letter Hairstreaks mating

White-letter Hairstreak eggs

White-letter Hairstreak larvae can be remarkably well camouflaged