1. Ministry of Agriculture, Fisheries and Food, Slough Laboratory, London Road, Slough, Berkshire, SL3 7HJ, UK
2. Department of Entomology, University of Georgia, Athens, Georgia 30602, USA (and Research Associate, Field Museum of Natural History, Chicago, Illinois 60605)
3. State University of New York, College of Environmental Science and Forestry, Syracuse, New York 13210, USA (and Research Associate, Field Museum of Natural History, Chicago, Illinois 60605)