Abstract: A field trial was conducted in 2008 in the Czech Republic to test the efficacy of kaolin (aluninosilicate mineral) against over wintered adults of Cacopsylla pyri. It aimed to prevent the females laying their eggs. Ekol (90% coleseed oil) was also tested in order to suffocate adults and eggs. In addition, the insecticides Sanmite 20 WP (pyridaben), Insegar 25 WP (fenoxycarb) and Calypso 480 SC (thiacloprid) were applied to reduce nymphs. These treatments were repeated on the first and the second generation. Efficacy was compared with an untreated control. Beating tray samples were taken in both plots (control, treatment) to monitor the density of adults. Egg-laying and nymph infestation were visually monitored. The Cacopsylla pyri population was not reduced under a damaging level. This observation might be explained by a high initial infestation level and the immigration of pear suckers from the untreated control plot. However, during the vegetation period it was observed that there were lower number of adults, nymphs and eggs on treated trees compared to the untreated control. The population density was significantly decreased, but not under the economic threshold (10 eggs or nymphs / 100 leaves). Yield was not decreased and no honeydew and sooty moulds were observed on the fruits.