White-letter Hairstreak

Durham Priority Species
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White-letter Hairstreak Action Plan

Priority Species: White-letter Hairstreak

Priorities
1. Safeguard existing populations and achieve a more widespread distribution of white-letter hairstreak
2. Increase the area of suitable habitat, that supports populations of white-letter hairstreak

Targets
Vision Statement: To improve survey coverage for white-letter hairstreak and provide better understanding of its distribution in the Durham BAP area

Target Type Unit Value
1. To maintain the range of the white letter hairstreak in the Durham BAP area. maintain occupied tetrads

This small and elusive butterfly is intimately associated with elm trees, where it lays its eggs and which, subsequently, provides food for the larvae. Various elm species are used, including Wych Elm (Ulmus glabra), English Elm (U. procera) and Small-leaved elm (U. minor), although Wych Elm may be preferred.  The butterfly breeds where elms occur in sheltered hedgerows, mixed scrub, edges of woodland rides and large isolated elms. In the past the species has not been well recorded, as they are hard to see as adults. However the devastation of the elm population by Dutch Elm disease in the 1970s has led to concern for this elusive species, and there has been more recorder effort nationally since the 1980s.

The species is single brooded with adults on the wing from the beginning of July to mid-August (depending on the weather), but is often more likely to be recorded in its egg stage which lasts from August until the following mid April.

Many colonies are likely to have become extinct with losses of large elms, but the butterfly can breed on abundant sucker regrowth near dead trees.

Local status

The White-letter hairstreak is near the northern limit of its range in Durham, although global warming is pushing this limit northwards. Records are scattered across lowland areas of Durham, and there are likely to be colonies as yet unrecorded.

Threats

  • Loss of suitable habitat through decline in hedgerows, removal of elm scrub, loss of elm trees to Dutch Elm Disease.
  • Loss of suitable habitat through early hedgerow trimming.
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