The compounds of the formula (I) (I) in which X denotes CH2 or O, R1 denotes (subst.) pyridyl or (subst.) pyrimidyl, R2 and R3 denote alkyl or alkenyl or R2 and R3 denote an alkylene chain, R4 denotes -H, -CN, -CCl3, -C 3BOND CH, alkyl, F, or -C(S)-NH2, R5 denotes pyridyl, furyl, thienyl, phthalimidyl, di(C1-C4)alkylmaleimidyl, thiophthalimidyl, dihydrophthalimidyl or tetrahydrophthalimidyl, which may all be substituted, or substituted phenyl, or R4 and R5-together with the carbon atom bridging them-denote an optionally substituted indanyl, cyclopentenoyl or cyclopentenyl radical, have advantageous insecticidal, acaricidal and nematocidal properties.