A compound of formula (I): wherein R1 is pyrid-4-yl optionally substituted by one to four substituents independently selected from halogen, C1-3 alkyl or C1-3 haloalkyl; R2 is hydrogen, halogen, C1-4 haloalkyl or C1-4 haloalkoxy; R3 is trifluoromethyl, difluoromethyl or difluoromethoxy and R4 is hydrogen, fluoro or chloro, or R3 is fluoro, chloro or bromo and R4 is fluoro, chloro or trifluoromethyl; and R5 is hydrogen or halogen; or salts or N-oxides thereof. Furthermore, the present invention relates to intermediates used to prepare compounds of formula (I), to methods of using them to combat and control insect, acarine, mollusc and nematode pests and to insecticidal, acaricidal, molluscicidal and nematicidal compositions comprising them.