White-letter Hairstreak butterflies

White-letter Hairstreak butterflies are under serious threat. This is directly linked with the substantial decline in the number of elm trees over the past 40 years. However, as one of the UK’s leading tree specialists and growers, here at Hillier, we have a solution that could save this rare butterfly from extinction.

Taking its name from the letter “W” that is created by the white zig-zagged lines found on its hindwing, the White-letter Hairstreak butterfly is a vital contributor to the wider environment as a natural pollinator and has become a priority species for conservation bodies such as Butterfly Conservation. It was this organisation that recently discovered White-letter Hairstreak successfully breeding on Hillier elm trees in Vauxhall Pleasure Gardens, London.

White-letter Hairstreak butterflies find habitats solely in elm trees, but the widespread reach of Dutch Elm Disease (DED) since the 1970s has seen the UK population of elm trees staggeringly drop by more than 30 million. In correlation with this, the population of the White-letter Hairstreak has dropped by 96%, leaving it at a critically low level.

Hillier, with our expertise in horticulture and tree development, is the exclusive UK grower of Ulmus New Horizon, an elm tree which is part of the resister elm breeding program, that is proven to be 100% resistant to DED and subsequently supports the White-letter Hairstreak butterfly.

Our vision is to bring the return of elm trees to the British landscape whilst saving the endangered butterfly species. U. ‘New Horizon’ is a versatile, hardy elm that can thrive anywhere. Derived from the Ulmus japonica and the Ulmus pumila, the UNH has been extensively tested and exposed to vast quantities of the fungus that causes DED – in much larger quantities than would be naturally encountered.

Account manager, Jim Hillier, commented: “We are incredibly excited about this discovery. Dutch Elm Disease has wreaked havoc among the tree population for years, and we believe that Ulmus new Horizon is the answer to providing mature elms for the future. It’s also key to the survival of the threatened White-letter Hairstreak butterfly. This discovery will increase the long-term habitats for the rare butterfly, providing food and breeding grounds, which will ultimately increase the population. At Hillier, we continue to focus on the natural world whilst also meeting customer demand for DED resistant trees and introducing new plants and trees.”.

Hillier promotes horticultural development, innovation and inspiration which is reiterated in this project as each tree is micro-chipped to allow us to track the development whilst continuing ongoing research.