In field trapping tests conducted in Hungary large numbers of Pyralis costalis F. (Lepidoptera: Pyralidae), a secondary pest, were attracted to traps baited with iso-amyl alcohol (3-methyl-1-butanol) and acetic acid. The same bait attracted lower numbers of P. farinalis L., a well-known stored product pest. In both spp. the capture of the two-component blend was significantly higher than the catch in traps with the single components. In tests conducted in a country mill, the blend of the above two compounds proved to be attractive towards Anagasta kuehniella Zell. and Plodia interpunctella Hbn. (Lepidoptera: Phycitidae), both important pests of stored products worldwide. The majority of captured insects were females. The optimal ratio for attracting A. kuehniella was 1:1 to 1:10 iso-amyl alcohol:acetic acid. The related iso-amyl acetate was inactive. The addition of iso-butyl alcohol (2-methyl-1-propanol) did not influence activity of the iso-amyl alcohol / acetic acid blend. Polyethylene dispensers with 0.2 ml of the blend started to loose activity only after 3 weeks of field exposure. Application possibilities of the newly discovered attractant are discussed.