The present invention provides compounds of formula (I): wherein A1, A2, A3 and A4 are independently of one another C—H, C—R5, or nitrogen; B1—B2—B3—B4 is —CH2—C═N—CH2—, —CH2—N—CH2—CH2—, —CH2—C═CH-0- or —CH═C—CH2-0-; G1 is oxygen or sulfur; L is a single bond or C1-C8alkylene; R1 is hydrogen, C1-C8alkyl, C1-C8alkylcarbonyl-, C1-C8alkoxy, C2-C8alkenyl, C2-C8alkynyl, C1-C8alkoxy-C1-C8alkyl, aryl or aryl substituted by one to three R6, or R1 is heterocyclyl or heterocyclyl substituted by one to three R6 or C1-C8alkoxycarbonyl-; R2 is hydrogen, C1-C8haloalkyl or C1-C8alkyl; R3 is C1-C8haloalkyl; R4 is aryl or aryl substituted by one to three R6, or R4 is heterocyclyl or heterocyclyl substituted by one to three R6; Y1 is CR7R8, C═O or C═S; Y2, Y3 and Y4 are independently CR7R8, C=0, C═S, N—R9, O, S, SO or SO2; wherein at least two adjacent ring atoms in the ring formed by Y1, Y2, Y3 and Y4 are heteroatoms; each R7 and R8 is independently hydrogen, halogen, C1-C8alkyl, or C1-C8haloalkyl; and R5, R6, R7, R8 and R9 are as defined in the claims. The invention also relates to processes and intermediates for preparing these compounds, to insecticidal, acaricidal, nematicidal and molluscicidal compositions comprising these compounds and to methods of using these compounds to control insect, acarine, nematode and mollusc pests.