PURPOSE: To obtain a new diphenyl ether deriv. having superior insecticidal and miticidal actions and exterminating harmful organisms.

CONSTITUTION: This diphenyl ether deriv. is a compd. represented by formula I (where X is F or Cl and Z is NH-CS-NH or N=C=N), e.g. N-2,6- diisopropyl-4-(2-chlorophenoxy)phenyl-N'-tert. butyl thiourea. The compd. is obtd. by allowing an isothiocyanate represented by formula II to react with tert. butylamine represented by the formula H2N-C(CH3)3 at 0-150°C in a proper solvent such as THF. The compd. represented by the formula I may be converted into carbodiimide by reduction with hydrogen sulfide. The compd. represented by the formula II is also new and is obtd. by converting aniline into thiophosgene. A harmful organism exterminating compsn. contg. 0.1-99 wt.% of the compd. represented by the formula I as an effective component exterminates arthropods, especially insects and mite.