The biology and pest status of the common species of Sitobion, Metopolophium and Rhopalosiphum found on wheat, barley and oat crops in Europe is critically reviewed. After preliminary sections on species and sampling, the factors that induce the production of the different morphs of cereal aphids are considered. Basic life-cycles are described and the importance of migration and dispersal considered. Host-plant preferences, survival and reproduction on different Gramineae, and feeding site preferences are considered, particularly in relation to the type and amount Of damage caused by the aphids. The effects of constant temperatures on the biology of some species have been investigated, but little is known about the effects of weather in the field. There have been few quantitative studies on the effects of natural enemies on cereal aphids, but the evidence suggests that they may be important in reducing their numbers. Side-effects of pesticides and fertilisers on aphids are also discussed. Aphids may reduce grain yield and quality. Direct damage may result from reductions.

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Abstract. 1. Small arenas in the field were used for observing adult Agonum dorsale (Pont.) foraging in a wheat crop. 2. The carabid showed no significant change in behaviour between low and high aphid density arenas. 3. Individuals foraged nocturnally and spent most of their time on the ground searching for prey. They climbed infrequently and then not high enough to reach aphid aggregations on the ears and flag leaves of wheat. 4. Gut dissection showed that more individuals had eaten aphids in the high aphid density arena than the low. Recording of aphid distribution within the arenas showed that this increase in aphid consumption could be explained by A.dorsale capturing aphids on the ground. Prey availability per unit area was in fact higher on the ground than on the wheat. 5. The contribution of ground‐zone predators such as A.dorsale to the control of cereal aphids will be determined by the frequency with which aphids arrive on the ground and the proportion of these which reclimb the wheat and reproduce in the absence of predation.