Monitoring and forecasting insect pests of cereals.
Data on the numbers (/m2) of stem-boring Diptera and cereal aphids found in cereals in the Game Conservancy West Sussex study area between 1972 and 1977 were considered. Oscinella frit was the dominant species in 1976, Opomyza florum in 1972, 1973 and 1975, O. germinationis in 1974 and Chlorops pumilionis in 1977. Most stem-borers were found in 1976 and fewest in 1977. The distribution of the species in the different cereal crops was also described.
Significant negative relationships were found between the numbers (/m2 ) of cereal aphids in winter wheat crops in the third week of June and deviations from the long term mean March temperature (r= -0.93, P<0.01) and between the peak numbers (/m2) in the different years and deviations from the long term mean April temperature (r= -0 .86, P<0.05). There was also a highly significant relationship (r= 0.98, P<0.001) between the number of 'air frost days' in April and the peak numbers (/m2) of aphids.