Research was carried out in 2001-2002, in the Plant Breeding Station of Mikulice near Przeworsk. The occurrence of European corn borer (Ostrinia nubilalis Hbn.) on corn, as well as the effects of its chemical control were assessed. It was found out that in 2001, caterpillars damaged 40.5% of plants, while in 2002 - 99.3% of plants. As a result of double lambda cyhalothrin application (Karate 025 EC), high pest reduction was achieved: 91.4% in 2001 and 88.9% in 2002. Corn yields increased by 1.8 t/ha in 2001 and 4.3 r/ha in 2002 in comparison with yields in untreated fields.