Butterfly monitoring

Harker, R.J. & Shreeve, T.G. (2008) How accurate are single site transect data for monitoring butterfly trends? Spatial and temporal issues identified in monitoring Lasiommata megera. Journal of Insect Conservation, 12, 125-133.
Brereton, T.M., Roy, D.B., Middlebrook, I., Botham, M.S. & Warren, M.S. (2011) The development of butterfly indicators in the United Kingdom and assessments in 2010. Journal of Insect Conservation, 15, 139-151.