Before the late 1960s studies in these phenomena were largely descriptive, but host-locating by blood-sucking flies was an exception. Work in this area was stimulatedby the recognition that an understanding of host-finding behavior might provide effective means of monitoring populations and perhaps even controlling them. Work on phytophagous insects has subsequently been stimulated by the world food shortage and the realization that here, too, the knowledge would be of practical importance. Further impetus has been derived from the increasing interest in evolutionary biology and the concept of plant-herbivore coevolution. At the same time, developments in chemical techniques (making it possible to collect, identify, and quantify minute quantities of volatile chemicals) and in electron microscopy and electrophysiology (making it possible to understand the mechanisms of olfactory perception) have allowed research to advance in a way that previously was impossible.
Most recent research has focused on two areas: identification of the chemicals ...
