SUMMARYSitona lineatusandApion voraxwere the two most common species of weevil on field beans(Vicia faba minor)at Rothamsted between 1970 and 1974. In glasshouse tests,A. voraxwas a much more efficient vector than 5.lineatusof broad bean stain virus (BBSV) and Echtes Ackerbohnenmosaik‐Virus (EAMV), and both species transmitted EAMV more often than BBSV. Five other species ofApiontransmitted the viruses infrequently or not at all.S. lineatusadults transmitted no more often after 8–16 days on infected plants than after 1–2 days. SomeA. voraxadults transmitted EAMV, but not BBSV, after feeding on infected leaves for a few minutes. After 4 days on infected plants,A. voraxsometimes remained infective for the following 8 days. NoA. voraxcollected from woodland plants in spring was infective with BBSV or EAMV, but 4% from bean crops containing seed‐borne infection carried BBSV and 17% carried EAMV. BBSV and EAMV were recovered from triturated weevils, but not from weevil haemolymph. Possibly the viruses are transmitted as contaminants of the mouthparts or by regurgitation during feeding, butA. voraxwas observed to regurgitate only when anaesthetized.BBSV and EAMV were not transmitted by aphids(Aphis fabaeandAcyrthosiphon pisum),nor by pollen beetles{Meligethesspp.).Field observations suggest that infected seed is the main source of BBSV and EAMV in spring‐sown crops, and that crops grown from virus‐free seed, and isolated from infected crops by 250–500 m, remain free of infection for most