The large-scale, long-term decline in wild bees across England has been linked to the use of neonicotinoid insecticides by a new study. Over 18 years, researchers analysed bees who forage heavily on oilseed rape, a crop widely treated with neonics". The scientists attribute half of the total decline in wild bees to the use of these chemicals. Several studies, conducted in the lab and in the field, have identified a negative effect on honey bees and bumble bees from the use of neonics. But few researchers have looked at the long term impacts of these substances. This new paper examined the impacts on populations of 62 species of wild bees across England over the period from 1994-2011. The team ... used distribution data on wild bees, excluding honey and bumblebees collected by the bees, ants and wasps recording scheme. They were able to compare the locations of these bees and their changing populations with growing patterns of oilseed rape across England over 18 years. The amount of this crop being sown has increased significantly over the period of the study, from around 500,000 hectares in 1994 to over 700,000 in 2011. A key innovation was the commercial licensing of neonicotinoid insecticides for the crop in the UK in 2002. Seeds are coated with the chemical and every part of the plant becomes toxic. The European Food Safety Authority is currently conducting a review of the scientific evidence about neonicotinoids. An EU-wide moratorium on their use was implemented in 2013 and is still in place.