2-PROPARGYLOXY-BENZAZOLS, MANUFACTURE, VERMIN REPELLENT CONTAINING THEM, PREPARATION THEREOF AND USE

Pesticidal compsn. comprises at least one cpd. effective against arthropods (esp. carbamates, carboxylates, phosphorus cpds. or halogenated hydrocarbons) and as synergist at least one cpd. of formula (I). In (I), R1 to R4 are each H, halo, alkyl or alkoxy (opt. substd. by halo), nitro, cyano, alkylcarbonyl or alkoxycarbonyl, or two of them together form a benzo ring; X is oxygen or sulphur. (I) are new cpds. provided than when X is sulphur then R3 is not nitro. The compsns. are useful for control of mites, spiders and esp. insects in agriculture, forestry, protection of stored materials and for hygienic applications. They have excellent residual activity on clay and wood and are stable on white-washed surfaces. (I) are more effective synergists than piperonyl butoxide and can be used with a wider range of pesticides.