A compound of formula (I), wherein A1, A2, A3, A4, G1, L, R1, R2, R3, R4, Y1, Y2 and Y3 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, molluscicidal and nematicidal compositions comprising them and to methods of using them to combat and control insect, acarine, mollusc and nematode pests.