ABSTRACT
The strains of P. farinosus capable of killing the cockroach Blattella germanica L. were selected. The experiment was carried out using mature insects in age groups and sex groups. The results showed differences in the insecticidal capability of the tested strains in this population of insects. Strains 5, Ł, P of P. farinosus were accepted as possibly useful against Blattella since at relatively low concentration of spores they produced a high mortality of the insects.