PRELIMINARY STUDIES ON POTATO APHIDS IN NORTH AND NORTH‐EAST SCOTLAND

Studies of potato aphids made in the potato seed‐growing areas of north and north‐east Scotland during 1950‐3 showed that potato plants were first infested during July, but with few aphids; maximum populations did not develop until mid‐late August or early September, which is the period of potato haulm destruction in seed crops. Myzus persicae (Sulzer) was scarce in rural districts and most numerous near urban areas. The main influx of alatae occurred in early August. Aulacorthum solani (Kltb.) was the predominant species north of Inverness. Macrosiphum euphorbiae (Thomas) was present in small numbers in many potato fields, but Aphis nasturtii (Kltb.) was extremely scarce. Because of the small numbers of aphids found during two years by examining two or three compound leaves per haulm, it was preferable to count the aphids on one main stem and all its leaves. Stove‐pipe sticky traps provided information complementary to complete stem/leaf examination, but are considered to be of doubtful use in an area where aphids are few.