The four dimensions of cereal aphids

For most of this century, aphids have been known to infest cereals, but their potential importance does not seem to have been fully appreciated until the early 1950s when they were found to be vectors of barley yellow dwarf virus (Bruehl, 1961). Although this discovery initiated a great deal of research in many countries, especially in North America, very little was done, or thought necessary to be done, in Britain. In 1968, however, some of this complacency was lost when the large numbers of aphids found on the cereals in this country indicated how little was known about them and their effects. Aphids are part of a complex four‐dimensional continuum of time and space, and this paper briefly describes some of the results obtained since 1969.