New elm trees encourage butterfly biodiversity in Crabtree Plantation

People walking through Crabtree Plantation this July may get the chance to see a very rare butterfly, thanks to a tree planting project undertaken by Basingstoke and Deane Borough Council.

Elm trees with a high-resistance to Dutch Elm Disease have been planted to encourage a small colony of White-letter Hairstreak butterflies to flourish.

The White-letter Hairstreak is one of Hampshire's rarest butterflies. It spends most of its time flying around the tree canopy, but occasionally descends to take nectar from thistle and bramble flowers.

Crabtree Plantation’s White-letter Hairstreaks have in the past been dependant upon Wych Elm, the UK’s only truly native elm tree. However, Wych Elm, like English Elm and Field Elm, is very susceptible to Dutch Elm Disease.

Since the outbreak of Dutch Elm Disease in the late 1960s, over 85% of Britain’s mature native elm trees have died. Although Crabtree Plantation’s elms are healthy at the moment, they will inevitably succumb to Dutch Elm Disease. When their bark ages, they become suitable habitat for the Scolytus beetles, which then transmit the dreaded Dutch Elm Disease.

But cultivars with a high resistance to Dutch Elm Disease do exist. They have been derived mostly from the hybridization of European and Asiatic species.

Basingstoke and Deane Borough Council have planted several of these in Crabtree Plantation. It is hoped these elms will thrive and provide a haven for Crabtree Plantation’s existing colony of White-letter Hairstreaks.

Cabinet Member for the Environment Cllr Anne Court said: “We took delivery of these disease-resistant elm trees three years ago. Local Tree Warden Julie Powel then looked after these on her allotment tree nursery until they grew strong enough to plant out. They should help sustain the White-letter Hairstreak colony for some years to come.

”Activities such as this are important ones in terms of the council’s entry to Britain in Bloom. Conservation and biodiversity are important factors in the competition. Judges also look at whether people are being encouraged to visit areas of natural beauty and to consider conservation issues. “

The White-letter Hairstreak butterfly never rests with its wings open, but is instantly identifiable by the white letter ‘W’ and orange margin on the underside of the hind wing.

The female lays her eggs on the twigs of elm trees. The caterpillars emerge the following spring and initially eat the elm flower buds, progressing to the seeds and ultimately the leaves. They pupate in June and emerge as adult butterflies in July.

Crabtree Plantation is a public open space on the A30 to the east of the town centre. There is no charge for public access to Crabtree Plantation and it is an ideal destination for a bank holiday family outing. It has a network of paths for walkers to enjoy and a cycle path for cyclists. There is also an area with picnic tables for visitors to use and a zip-wire is situated near to the ponds and Black Dam nature reserve. The area also hosts a wide variety of plant and animal life.