White-letter Hairstreak Satyrium w-album

Habitat

The White-letter Hairstreak is found in woodland edges and rides, and sheltered hedgerows. It depends on elm trees and was severely hit by Dutch Elm disease during the 1970's and 80's. Fortunately the caterpillars have been found to survive on new sucker re-growth as well as fully mature trees, and populations have now recovered in many places, although it is still cause for concern. Today it is fairly widespread and locally common throughout most of England, and its range has been extending northwards. Like the Purple Hairstreak it spends most of its time at high level feeding on honeydew, but will come down to nectar on flowers during early morning and late afternoon.

Identification

Both sexes are similar with a distinctive white 'W' on the dull brownish-grey underside of the hindwings. It may be confused with the Black Hairstreak, which has a brighter band of orange and a row of black spots along its inner edge.

Flight times

The White-letter Hairstreak is single brooded and overwinter as eggs, with adults on the wing during July and August.

Food plants

Eggs are laid on a variety of elm species.