The distribution of flying insects in and near a tall hedgerow.
In a further study on the distribution of cereal aphids and their predators and parasites in southern England [see RAE/A 62, 500, 3133], the distribution patterns of flying insects (mostly aphids and predatory Hymenoptera, syrphids and chrysopids) were measured in 1971 and 1972 at Rothamsted in England by means of suction traps in and near a tall hedgerow that was 7 m high, contained a variety of woody and herbaceous wild plants (which are enumerated) and separated a wheat field on the east from a broad-bean [Vicia faba] field on the west. Two suction traps were sited in the eastern and western sides of the hedge, another at a distance of 21 m in the middle of the wheat field east of the hedge and a fourth over a weedy site 56 m east of the hedge. In both years, insects were most numerous on the western side of the hedge irrespective of wind speed and direction. Numbers were smallest in the third trap and somewhat greater in the fourth although less than in either of the traps sited in the hedgerow. This pattern of distribution appeared to be determined primarily by the comparative richness of the vegetation surrounding the trapping sites, the western side of the hedge having the most varied flora.