The abilities of different aphid species to act as vectors of Carrot virus Y (CarVY) in carrots were studied. Their effectiveness at transmitting the virus from infected to healthy carrot plants was compared using 5-10 min acquisition access feeds. With species that colonise apiaceous hosts, the percentage transmission efficiencies found were Myzus persicae: 56; Dysaphis foeniculus: 19; Aphis spiraecola: 17; D. apiifolia: 13; Hyadaphis foeniculi: 7; Cavariella aegopodii: 4; and H. coriandri: 3. With non-colonising species, the respective transmission efficiencies were Lipaphis erysimi: 34; Hysteroneura setariae: 14; Brevicoryne brassicae: 12; Acyrthosiphon kondoi: 10; Sitobion miscanthi: 7; Rhopalosiphum maidis: 2; and R. padi: 0.5. When flying aphids were trapped on vertical nets near to a CarVY-infected carrot planting, 11 out of 101 H. foeniculi caught transmitted the virus to carrot seedlings but the 13 other aphids caught, which belonged to three non-colonising species, did not. If present in sufficient numbers, all 14 aphid species that transmitted the virus have the potential to be important CarVY vectors in carrot crops.