Part 1 Foraging behaviour, J.J.M. van Alphen and M.A. Jervis: behaviour of insect parasitoids and predators; methodology; the treatment of parasitoids prior to their use in experiments; recording and statistical analysis of behavioural data; host/prey finding and selection behaviour; deciding what clutch size to lay; host-feeding behaviour; host discrimination; sex allocation; functional responses; switching behaviour; patch time allocation; patch defence behaviour; distribution of parasitoids over a host population; measuring encounter rates; life history characteristics and searching behaviour; foraging behaviour and taxonomy; parasitoid behaviour and community ecology. Part 2 The life cycle, M.A. Jervis and M.J.W. Copeland: anatomical studies; female reproductive system; male reproductive system; sex ratio; locating eggs in hosts; fecundity; adult longevity; growth and development of immatures; survival of immatures; intrinsic rate of natural increase. Part 3 Mating behaviour, H. van den Assem: making records; general methodology; equipment used in observing mating behaviour; the early stages of mating behaviour; stimulus production; some quantitative aspects of mating behaviour; female receptivity and its consequences; aspects of mating "sensu stricto"; mating success; comparative studies of mating behaviour. Part 4 Populations and communities, W. Powell and .M.P. Walton: field sampling techniques; determining trophic relationships; genetic variability in field populations of natural enemies. Part 5 Population dynamics, N.A.C. Kidd and M.A. Jervis: demonstrating and quantifying predation and parasitism; the role of natural enemies in insect population dynamics; selection criteria in biological control. Part 6 Phytophagy, M.A. Jervis and N.A.C. Kidd: what plant materials do natural enemies feed upon, and from what sources?; do natural enemies show specificity in the plant food sources they exploit?; interpreting patterns of resource utilization; insect preferences and foraging energetics; natural enemies as pollinators.