Most butterflies are still hibernating after a reassuringly normal March following the February heatwave. Our five hairstreak species all hibernate in their minuscule eggs, stuck fast to bare branches – a wise and robust strategy. The white-letter hairstreak, a diminutive dark butterfly with a white W on its underside, has declined by 93% since the 1970s because Dutch elm disease has destroyed the trees on which its caterpillars feed.
Tree-dwelling butterflies are elusive, but also easy for us to help. We live alongside them in cities. One of the white-letter’s strongholds is Brighton, where 17,000 elms have largely escaped the ravages of disease. There’s some good help for this hairstreak this year. At the University of Sussex, Crispin Holloway, a life sciences technician, searched the branches of a disease-stricken elm for the hard-to-see hairstreak eggs as it was felled, rescuing 40 eggs.
Elsewhere in Sussex this year, students are planting more than 500 disease-resistant elm hybrids at Lancing College as part of a butterfly conservation project to provide new habitat for the hairstreak.
We can all join in with this simple, feelgood conservation that heightens our awareness of neighbourhood nature.
