One of common cereal pests in Poland are flies of the Agromyzidae family. The larvae of these flies is the stage which is harmful. Leaf miner larvae feeding on the leaf parenchyma cause characteristic damage (mines). Their widespread occurrence con- tributes to a reduction in leaf assimilation surface. Leaf miner larvae mostly damage first-flag and second leaves. Their damage has a negative effect on the yield parameters. Locally they cause losses of economic significance. The flight of leaf miner imagines coincides with the development of leaf beetles (Oulema spp.), another dangerous cereal crop pest. The aim of the conducted research was to determine the optimum time for chemical treatment of leaf mining flies and leaf beetles as part of integrated cereal protection. To achieve that aim, field experiments were conducted in the years 2008–2009 at the Research Station for Variety Testing in Słupia Wielka (the county of Środa Wielkopolska) using winter wheat of the Bogatka variety. Values monitored included the dynamics of flight for leaf mining flies along with the speed of leaf beetle development. The accuracy of the suggested dates was measured by the quantity of the yield obtained. Additionally, the species composition of Agromyzidae damaging winter wheat was also analyzed. During the years of the research, the biggest yields were obtained when both pest species were chemically treated during the period when the leaf mining flies were abundant and when the oldest leaf beetle larvae reached the size of about 2 mm (in the year 2008) and about 4 mm (in the year 2009). It was also determined that the species composition of Agromyzidae damaging winter wheat changes between particular years.