Problems with aphids in small grain cereals, either direct by feeding, or indirect by transmission of Barley Yellow Dwarf Virus, are expected to increase due to climate change and a recent ban on neonicotinoid seed treatments by the European Union. Moreover, insecticide resistance against pyrethroid insecticides is reported at multiple locations throughout the world. Therefore, a better understanding of cereal aphid population dynamics and increased attention towards an integrated pest management is needed. In this study, cereal aphids were monitored on 193 maize and small grain cereal fields throughout Flanders, Belgium. The population dynamics and species distribution were observed throughout the year and the effects of spatio-temporal variables were explored. A significant negative effect was found of grassland in a 1,000 m radius and a positive effect of grain maize in a 3,000 m radius around a small grain cereals field on the maximum infestation rate with aphids in autumn within this field. In a 3,000 m and 5,000 m radius, a significant positive effect of grain maize and a significant negative effect of other small grain cereals was found on the maximum infestation rate during the whole growing season within this field. The mean daily average temperature from 118 to 19 d before sowing had a significant positive effect on the maximum infestation rate in autumn. Mean precipitation, wind speed, and humidity from 52 to 26, 46 to 23, and 107 to 13 d before sowing respectively, had a significant negative effect on the maximum infestation rate in autumn.