Flight behaviour of the bird cherry aphid, Rhopalosiphum padi

Seasonal winged forms of the bird cherry aphid, Rhopalosiphum padi L., were flown in an automated flight chamber. During their maiden flights, autumn migrants (gynoparae) had a greater initial rate of climb than summer (exules) and spring migrants (emigrants). Autumn migrants, presented with a laterally-positioned green-illuminated target for 2.5 s during each minute of flight, flew for a longer period before responding to the target (110 min) than summer migrants (36 min), while spring migrants responded after an intermediate time (72 min). This period is equivalent to the migratory phase of flight. The summer migrants were maximally responsive to targets illuminated by green monochromatic light (lambda-555 nm). Targets illuminated with ultraviolet (lambda-360 nm) were attractive during the migratory and green-responsive phases of flight, but infrared (lambda > 700 nm) wavelengths were not attractive. The results are discussed with respect to aphid behaviour in the field.