Abstract: The 1,4-diaryl-1-cyclopropyl-4-substituted butane pesticides of the following formula are effective as insecticides and acaricides: ##STR1## in which X and Y are independently hydrogen, halogen, alkyl, alkoxy, cycloalkylalkoxy, alkylcarbonyl, alkoxycarbonyl, haloalkyl, haloalkoxy, alkylthio, haloalkylthio, alkylsulfinyl, alkylsulfonyl, trialkylamino, nitro, or cyano; or X and Y together are --OCH.sub.2 O-- or --OCF.sub.2 O-- bridging the 2-3 or 3-4 positions of the phenyl ring; Ar is 3-phenoxyphenyl, 4-fluoro-3-phenoxyphenyl, 6-phenoxypyridin-2-yl, or 2-methyl(1,1'-biphenyl)-3-yl;R is cyano, methyl, trifluoromethyl, alkenyl, alkynyl, or halogen.