The connection between the study of insects. their development. behaviour and biochemistry. and chromatography is perhaps not immediately obvious. However. this connection exists and it is of fundamental importance to our understanding of many areas of insect physiology. Insects range in size from small to minute and consequently the amounts of hormones or pheromones they produce are equally minute. Ultimately any attempt at understanding the processes which control development, social behaviour or the biochemistry of insects requires some means of isolating the tiny quantities of the hormones and pheromones responsible in sufficient quantity and purity for identification. The ability to devise novel techniques to separate these materials from frequently complex biological mixtures including precursors and metabolites and to devise detection systems for them is vital. Methods for the quantification of these substances at different stages in the life cycle. or in response to environmental change or stress. are then essential. Chromatography. both as a means for isolation and as a method for quantitative analysis. has "been an essential tool in these studies. This volume represents the outcome of a joint international symposium organized by the Chromatographic and Royal Entomological Societies at the University of Reading between the 21st and 23rd March 1989 aimed specifically at discussing the chromatography and isolation of insect hormones. pheromones and related substances.The papers presented at that meeting. and collected together here. covered many aspects of the subject including the chromatography of juvenile hormones. ecdysteroids. peptides. pheromones and semio- chemicals.