White-letter hairstreak

The white-letter hairstreak is an enchanting butterfly from the Lycaenidae family. This dark-hued beauty often resides in treetops, feeding on honeydew. It is distinguished by its dark brown upper wings and a striking white streak on the underside, forming a W or M pattern on the hindwings. Typically, it rests with its wings closed, usually positioned at right angles to the sun during the day.

Found across the Northern Hemisphere, this butterfly ranges from Europe and Siberia to the Russian Far East, Korea, and Japan, but it is absent from North America. In the UK, it has a scattered distribution, primarily in England, but is absent from Ireland, western Wales, and much of Cornwall. To aid in its conservation, efforts have been made to plant disease-resistant elm trees.

The life cycle of the white-letter hairstreak begins with eggs laid on elm trees. The caterpillars hatch in March and feed on the flowers and leaves. When ready to pupate, they do so under leaves or on twigs, with adult butterflies emerging from late June to mid-August in the UK. They are particularly fond of sipping nectar from flowers such as the creeping thistle and lime trees.