[Residual larval effects of permethrin and resistance in the housefly]

The effectiveness of synthetic pyrethroid permethrin in a special preparation Coopex, concentrations 0.25 and 0.5% against larval stages of housefly (Musca domestica) was tested. No larvicidal effect was proved in these commonly used concentrations. Under laboratory conditions, a very good residual effectiveness against imagoes, lasting more than 365 days (100% imago perish), was proved. In stables the residual effectiveness of Coopex was pronounced during 11 weeks. In ten generations of housefly, exposed to 0.001% concentration of Coopex, no resistance to 0.25% concentration of this substance was observed.