The Viability and Compatibility of Pollen on Insects Visiting Apple Blossom

Many apple cultivars are more or less completely self-incompatible and therefore require cross-pollinating. Although many insects are known to frequent apple blossom, much remains to be done in evaluating the effectiveness of different species as cross-pollinators. The tendency of an insect to carry compatible pollen has mostly been judged by observing its behaviour in orchards, and particularly the way in which it moves from tree to tree (e.g. Menke 1951, 1952; Free & Spencer-Booth 1964; Free 1966). Such information is difficult to obtain, owing to the small size and rapid movements of many blossom visitors, and can lead only to an indirect and speculative assessment. These difficulties have been partially overcome by using new techniques described in this paper.