Potato aphid, Macrosiphum euphorbiae (Thomas), is a highly mobile aphid species that dominates aphid communities in Maine potato fields and may contribute to virus transmission between potato plants. We studied effects of simulated rain, wind, mechanical raking, fungicide application, reflective mulch, and predator (lady beetle, Harmonia axyridis (Pallast) on the interplant movement of wingless adult potato aphids in greenhouse experimental arenas that imitated small segments of a potato field. The number of aphids dispersing from the central plant in the arena following tested perturbation was recorded. Experiments were repeated with 3-4 week old plants with non-overlapping canopies and with 4-5 week old plants with canopies overlapping within rows. Aphids moved between potato plants even when canopies did not overlap, and without any environmental perturbations. However, more aphids moved between larger plants with overlapping canopies. Rain significantly encouraged aphid movement between plants with non-overlapping canopies. Wind, rain, and mechanical raking significantly encouraged aphid movement between plants with overlapping canopies. Regardless of canopy overlap, most aphids moved within the rows of potato plants. However, there was also considerable movement between the rows, even though the aphids had to walk over bare soil. [Full Text]