To obtain the subject insecticide and acaricide highly effective in controlling insects and mites which are pests and effective in even protecting crops during the growth or harvested crops from damage caused by attack or invasion of the insects or mites.

This 1,4 diaryl 2,3-difluoro-2-butene is represented by formula I [Ar is phenyl or the like which may have one to three substituent groups (a halogen, a 1-4C alkyl or the like); R is H, a 1-4C alkyl or the like; R1 is H, F or the like; Ar1 is phenoxyphenyl or the like which may have one to six substituent groups (a halogen, a 1-4C alkyl or the like)], e.g. 4-(p- chlorophenyl)-2,3-difluoro-5-methyl-1-(m-phenoxyphenyl)-2-hexene. The compound represented by formula I is obtained by converting a compound represented by formula II into a compound represented by formula III with [CCH3OCH2CH2 O]2AlH2]Na and a mineral acid, then reacting the resultant compound with CH3(CH2)3Li, ZnCl2, Pd[P(C6H5)3]4 and Ar1CH2I.