The present invention relates to novel imidazoline derivatives and their use as insecticidal, acaricidal, molluscicidal and nematocidal agents. The invention also extends to insecticidal, acaricidal, molluscicidal and nematicidal compositions comprising such imidazoline derivatives, and to methods of using such derivatives and/or compositions to combat and control insect, acarine, mollusc and nematode pests. A compound of formula (I) and salts and N-oxides thereof, wherein: R1 is C1-10 alkyl; R2 is chloro, bromo or iodo; R3 is C2-5 alkyl, C1-5 haloalkyl, C1-6 hydroxyalkyl, C1-5alkoxy-(C1-3)-alkyl, di-(C1-5 alkoxy)-(C1-3)-alkyl, C1-5alkylthio-(C1-3)-alkyl; C1-5 alkylsulfinyl-(C1-3)alkyl; C2-5 alkenyl, C1-5 haloalkenyl, C2-5 alkinyl, C3-6 cycloalkyl, C3-6 cycloalkenyl, hydroxy, C1-5 alkoxy, C1-5haloalkoxy, C1-5alkylthio, C1-5 haloalkylthio, formyl, cyano, bromo, or iodo; Z is hydrogen, hydroxy, nitro cyano, rhodano, formyl, G-, G-S—, G-S—S—, G-A-, R7R8N—, R7R8N—S—, R7R8N-A-, G-O-A-, G-S-A-, (R10O)(R11O)P(X)—, (R10O)(R11S)P(X)—, (R10O)(R11)P(X)—, (R10S)(R11S)P(X)—, (R10O)(R14R15N)P(X)—, (R11)(R14R15N)P(X)—, (R14R15N)(R16R17N)P(X)—, G-N═CH—, G-O—N═CH—, N≡C—N═CH—, or Z is a group of formula (II), wherein B is S—, S—S—, S(O)—, C(O)—, or (CH2)n—; n is an integer from 1 to 6; and R1, R2, and R3 are as defined above; and G is optionally substituted C1-10alkyl, optionally substituted C2-10 alkenyl, optionally substituted C2-10 alkynyl, optionally substituted C3-7 cycloalkyl, optionally substituted C3-7 cycloalkenyl, optionally substituted aryl, optionally substituted heteroaryl or optionally substituted heterocyclyl; A is S(O), SO2, C(O) or C(S).