The invention relates to compounds of formula (I): where A1, A2, A3, A4, G, R1, R2, R3 and R4 are as defined in claim 1; or a salt or N-oxide thereof. Furthermore, the present invention relates to processes and intermediates for preparing compounds of formula (I), to insecticidal, acaricidal, nematicidal and molluscicidal compositions comprising the compounds of formula (I) and to methods of using the compounds of formula (I) to control insect, acarine, nematode and mollusc pests.