Previously published in hardback and now made available in paperback, this ground-breaking book is a must for all interested in butterflies, whether as conservation biologist, amateur or professional entomologist or as a student studying the phenomenon of butterfly populations as part of a number of biology, ecology or conservation courses. Recently, many British butterflies have suffered severe declines whole others have flourished and expanded in range. This is the first book to describe the results from a British scheme to monitor butterflies during this period of change. The Monitoring Scheme, initiated in 1976 by the senior author is based on frequent counts at some 90 sites throughout Britain. The combined efforts of both amateurs and professionals have thus produced a dataset with no equivalent elsewhere in the world. The book therefore provides a unique perspective on trends in numbers, extinction and foundation of populations; flight periods, local distributions, migration and other aspects of population ecology. Practical problems encountered during the conservation of butterflies of individual sites are outlined. The relevance of this monitoring for an understanding of the effects of the weather - climatic warming - is described.

Studies were made on insecticide spray drift from conventional hydraulic sprayers under typical agricultural conditions. A bioassay technique with 2-day-old Pieris brassicae larvae was used to assess drift of cypermethrin and triazophos from pea and brassica crops on six occasions. Earlier work had shown that this species was a suitable model for other butterflies. Replicated series of target larvae were placed downwind of the sprayed crops, and mortality data used to obtain profiles of spray drift related to physical features such as roadways, adjacent crops and hedges. Estimates of the distances at which 50%, 20% and 10% mortality occurred were obtained graphically or by fitting logistic models to the data. Buffer zones that limited mortality to 10% or less were between 16 and 24 m for cypermethrin and 12 m for triazophos. These estimates made no allowance for control mortality of about 5%, however, they were based conservatively on short-term effects. Hedges also probably limited the full extent of drift in two instances. The wider application of these results is discussed and comparisons are made with the use of unsprayed crop headlands.