1. School of Biological Sciences; Victoria University of Wellington; PO Box 600 Wellington New Zealand
2. School of Mathematics and Statistics; Victoria University of Wellington; PO Box 600 Wellington New Zealand
3. 17 Elmfield Terrace York YO31 1EH UK
4. Rothamsted Insect Survey; Department of Agroecology; Rothamsted Research; Harpenden Hertfordshire AL5 2JQ UK