Flight activity ofRhopalosiphumspp. was recorded in a suction trap between 1981 and 1987. Field studies on cereals in Canterbury during the period 1984–1987 showed thatRhopalosiphum padiL., the most frequent species, was usually present at low densities and only occasionally reached maxima greater than 10 aphids per tiller on wheat (Triticum aestivumL.) or barley (Hordeum vulgareL.). Greater numbers ofR. padiwere found on rye (Secale cerealeL.) than on wheat, barley, oats (Avena sativaL.), or ryegrass cv Tama (Lolium perenne × multiflorum).Rhopalosiphum maidis(Fitch) was frequent on barley in 1985 and 1986 but was rare in other years.Rhopalosiphum insertum(Walker) andR. rufiabdominalis(Sasaki) were recorded on cereals in autumn 1987. Comparison of suction trap catches and numbers of winged aphids landing on cereals showed thatR. padiconcentrated on barley crops to a lesser extent than didR. maidisorMetopolophium dirhodum(Walker).