EN
There were tested water extracts from selected Geraniaceae plants. It was observed that the plant extracts investigated inhibit feeding and development of Colorado potato beetle. The greatest antifeedant activity towards Colorado potato beetles and their larvae was noted for Pelargonium x hortorum Bailey and Geranium sanquineum L. extracts. The Pelargonium x hortorum Bailey extract added to food showed unfavourable effect on the development of female reproductive organs and significantly inhibited the number of eggs laid, however it showed effective neither towards the period of winter diapause nor towards spring emergence of beetles. The highest effectiveness under field conditions was recorded for extract from Erodium cicutarium L.