Roads should be re-routed to minimise harming butterfly populations or, failing that, ensure verges and other landscaped areas are suitable for butterflies, according to a Highways Agency-English Nature handbook. Examples where strategic roads have been realigned to protect threatened species – including the newly-widened A30 in Cornwall, which skirts around the edge of the special area of conservation of Goss Moor – were hailed as examples of good practice. But the guide also acknowledges how roadside verges have become ‘an increasingly-important habitat for butterflies,’ and outlines how this can be further encouraged. Roads engineers are urged to consider making verges as wide as possible, and to include the wildflowers and variations in topography needed by the 25 species of butterfly found in roadside areas. Expanding roads through areas of intensive farmland can, counterintuitively, ‘lead to a net gain for insect diversity’, the document states – provided the humps and hollows butterflies need to survive in both dry and wet summers are incorporated, and that past failures in introducing wild flowers on to verges are overcome. ‘Many landscaping schemes incorporating wildflower grassland have failed, a key problem being the weed seed banks that fertile topsoils contain. Success can be promoted by sowing wildflowers direct into nutrient-poor soils.’ The use of ‘ecoducts’ or grassed overpasses – introduced at a cost of £1.8M on a Netherlands’ motorway – are also suggested as a way of overcoming their inability to move to new habitats, one of the main harmful effects of roads on butterflies. One piece of research found that as few as 2% of Chalkhill Blues crossed the M3 at Twyford Down. Roads minister Dr Stephen Ladyman claimed the handbook showed the HA ‘takes its environmental responsibilities seriously’, demonstrating the wide range of steps it takes to protect butterflies. Road schemes such as the controversial M3 extension at Twyford Down have been misrepresented as ‘the destruction of high-quality wildlife habitat’, according to the guidance. ‘In fact, the true picture is one of biodiversity enhancement, particularly for butterflies’. The recreation of downland on the route of the old Winchester bypass increased the numbers of Chalkhill Blues, it claims.