The present Application discloses pesticidally active compounds of formula (I):Q(CH.sub.2).sub.a (O).sub.b Q.sup.1 CR.sup.2 .dbd.CR.sup.2 .dbd.CR.sup.3 CR.sup.4 .dbd.CR.sup.5 CXNR.sup.1 R.sup.xor a salt or propesticide thereof, wherein Q is an optionally substituted aromatic monocyclic or fused bicyclic ring system in which at least one ring is aromatic, or Q is a dihalovinyl group or a group R.sup.6 --C.tbd.C-- where R.sup.6 is C.sub.1-4 alkyl, tri C.sub.1-4 alkylsilyl, halo or hydrogen; Q.sup.1 is a 1,2-cyclopropyl ring optionally substituted by one or more groups selected from C.sub.1-3 alkyl, halo, C.sub.1-3 haloalkyl, C.sub.2-3 alkynyl, or cyano; or is (CH.sub.2).sub.7 ;a=0 or 1; b= 0 or 1;R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are the same or different with at least one being hydrogen and the others being independently selected from hydrogen, halo, C.sub.1-4 alkyl or C.sub.1-4 haloalkyl;X is oxygen or sulphur;R.sup.1 is phenyl optionally substituted by 1-5 substituents chosen from:a) C.sub.1-4 alkyl, C.sub.1-4 alkoxy, phenoxy and methylenedioxy, each optionally substituted by 1 to 5 halo;b) halo, cyano, nitro, formyl, C.sub.1-5 acyl;c) C.sub.2-3 alkynyl, C.sub.2-3 alkenyl, each optionally substituted by 1 to 5 halo;d) a group S(O).sub.n R.sup.7 wherein n=0,1,2 and R.sup.7 is C.sub.1-4 alkyl, halo or NR.sup.8 R.sup.9 wherein R.sup.8 and R.sup.9 are independently selected from hydrogen, C.sub.1-4 alkyl and C.sub.1-4 acyl;and a group e) NR.sup.8 R.sup.9 where R.sup.8 and R.sup.9 are as defined above;R.sup.X is hydrogen or an optionally substituted C.sub.1-8 alkyl or benzyl group, their preparation, pesticidal compositions containing them and their use against pests.