A compound of formula: wherein, R 1 and R 2 are each independently selected from C 1 -C 4 alkyl and C 3 -C 8 cycloalkyl; or R 1 and R 2 together with the nitrogen atom to which they are attached form a three to six- membered saturated cyclic group which may optionally contain one oxygen or one sulphur atom; R 3 is hydrogen, halogen or C 1 -C 4 alkyl; R 4 is C 1 -C 4 alkyl or C 1 -C 4 haloalkyl; R 5 and R 6 are each independently selected from C 1 -C 6 alkyl, C 1 -C 6 haloalkyl, C 3 -C 8 cycloalkyl, C 2 -C 6 alkenyl, C 2 -C 6 haloalkenyl, C 2 -C 6 alkynyl, aryl (optionally substituted with one to three R 7 groups), aryl(C 1 -C 4)alkyl wherein the aryl is optionally substituted with one to three R 7 groups, heteroaryl(C 1 -C 4)alkyl wherein the heteroaryl is optionally substituted with one to three R 7 groups and heteroaryl (optionally substituted with one to three R 7 groups); X is NR 8, O or S; Each R 7 is independently selected from halogen, cyano, hydroxyl, amino, nitro, C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 3 -C 6 cycloalkyl, C 3 -C 6 halocycloalkyl, C 1 -C 4 alkoxy, C 1 -C 4 haloalkoxy, C 3 -C 6 cycloalkoxy, C 1 -C 4 alkylthio, C 1 -C 4 haloalkylthio, C 3 -C 6 cycloalkylthio, C 1 -C 4 alkylsulfinyl, C 1 -C 4 haloalkylsulfinyl, C 1 -C 4 alkylsulfonyl, C 1 -C 4 haloalkylsulfonyl, C 1 -C 4 alkylcarbonyl, C 2 -C 6 alkenyl, C 2 -C 6 haloalkenyl, C 2 -C 6 alkenyloxy, C2-C6haloalkenyloxy, C2-C6alkynyl, C 3 -C 6 cycloalkylC 2 -C 6 alkynyl, C2-C 6 alkynyloxy, aryl, aryl(C 1 -C 4)alkyl, aryloxy, heteroaryl, heteroaryl(C 1 -C 4)alkyl and heteroaryloxy; and R 8 is selected from hydrogen, C 1 -C 4 alkyl, C 1 -C 4 alkoxy and C 3 -C 8 cycloalkyl; or a salt or an N-oxide thereof. R 1 and R 2 are each independently selected from C 1 -C 4 alkyl and C 3 -C 8 cycloalkyl; or R 1 and R 2 together with the nitrogen atom to which they are attached form a three to six- membered saturated cyclic group which may optionally contain one oxygen or one sulphur atom; R 3 is hydrogen, halogen or C 1 -C 4 alkyl; R 4 is C 1 -C 4 alkyl or C 1 -C 4 haloalkyl; R 5 and R 6 are each independently selected from C 1 -C 6 alkyl, C 1 -C 6 haloalkyl, C 3 -C 8 cycloalkyl, C 2 -C 6 alkenyl, C 2 -C 6 haloalkenyl, C 2 -C 6 alkynyl, aryl (optionally substituted with one to three R 7 groups), aryl(C 1 -C 4)alkyl wherein the aryl is optionally substituted with one to three R 7 groups, heteroaryl(C 1 -C 4)alkyl wherein the heteroaryl is optionally substituted with one to three R 7 groups and heteroaryl (optionally substituted with one to three R 7 groups); X is NR 8, O or S; Each R 7 is independently selected from halogen, cyano, hydroxyl, amino, nitro, C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 3 -C 6 cycloalkyl, C 3 -C 6 halocycloalkyl, C 1 -C 4 alkoxy, C 1 -C 4 haloalkoxy, C 3 -C 6 cycloalkoxy, C 1 -C 4 alkylthio, C 1 -C 4 haloalkylthio, C 3 -C 6 cycloalkylthio, C 1 -C 4 alkylsulfinyl, C 1 -C 4 haloalkylsulfinyl, C 1 -C 4 alkylsulfonyl, C 1 -C 4 haloalkylsulfonyl, C 1 -C 4 alkylcarbonyl, C 2 -C 6 alkenyl, C 2 -C 6 haloalkenyl, C 2 -C 6 alkenyloxy, C2-C6haloalkenyloxy, C2-C6alkynyl, C 3 -C 6 cycloalkylC 2 -C 6 alkynyl, C2-C 6 alkynyloxy, aryl, aryl(C 1 -C 4)alkyl, aryloxy, heteroaryl, heteroaryl(C 1 -C 4)alkyl and heteroaryloxy; and R 8 is selected from hydrogen, C 1 -C 4 alkyl, C 1 -C 4 alkoxy and C 3 -C 8 cycloalkyl; or a salt or an N-oxide thereof.