White Letter Hairstreak Butterfly - Satyrium w-album
The White-letter Hairstreak is one of our more-elusive butterflies as it flits high in the treetops. It gets its name from the letter "W" that is formed from a series of white lines found on the underside of the hindwings.
Elm is the sole foodplant and this species suffered as a result of Dutch elm disease in the 1970s and early 1980s. All species of elm were affected and there was concern that this species of butterfly might become extinct in the British Isles as a result.
This butterfly forms discrete colonies which are sometimes very small containing only a few dozen individuals. Colonies are typically focused on a small clump of trees or even an individual tree. These butterflies are not great wanderers and will reuse the same site year after year.
The adult butterflies are best seen early in the morning or late in the afternoon, when they will come down from their treetop resting place to nectar on various flowers, Thistle, Bramble and Privet being favourites. Most of the time, however, they remain elusive as they feed on honeydew in the tree tops. The adults never settle with their wings open.
When egg-laying, the female slowly crawls along twigs of the foodplant looking for suitable places in which to deposit her eggs.
Eggs are laid singly at all heights on elm trees and are a most-curious shape - a flattened sphere that has been compared to a flying saucer, with a flattened rim surrounding a central dome. It is typically laid on the scar that separates new and old growth and is green when first laid, but soon changes to a dark brown. The fully-formed caterpillar remains in the egg until the following spring.
White letter hairstreak Butterflies are found here at the Plotlands.