Water extractsfrom selected Geraniaceae plants, to which paraffin oil was added as adjuvant, were tested. It was observed that the plant extracts researched limited Colorado potato beetle feeding and development and adding adjuvant increased the effects. The highest antifeedant activity towards Colorado potato beetlesand their larvae wasobs erved in extractsobtained from Pelargonium × hortorum Bailey and Geranium pusillum L. The extract from Pelargonium × hortorum Bailey added to food showed a negative effect on the development of female reproductive organs and embryo development and showed the highest effectiveness in field conditions.