EN
Five field strains of Blattella germanica from different areas of Bulgaria were tested for resistance to DDT. The strain from Sofia-city after 24 hours of exposure was resistant to DDT in terms of mortality by resistant ratio of 3.76 at the LT₅₀ level. Also 5 strains of B. germanica from 3 regions of Bulgaria have beecn tested to the carbamate insecticide - Propoxur. For the. first time in Bulgaria, DDT- and Propoxur- resistant cockroach strains have been found. It is due to female and nymph resistance, while the males are highly susceptible to Propoxur.