After male adults of a mutant, or (orange body), and a KNIH (Korea National Institute of Health) strain of the German cockroach, Blattella germanica (L.), had been treated individually with chlorpyrifos and permethrin in sublethal doses, they were observed continuously for 4~5 days in semi- natural conditions, providing harborage, food, water and other individuals. Although individual variation was relatively high, visiting frequency and within-harborage time were generally decreased with the treatment of the insecticides. With the permethrin treatment to the or strain, however, within-harborage time was not decreased clearly, and visiting frequency in photophase remained in the similar level while it was decreased in scotophase. Generally diel differences in within-harborage time and visiting frequency were not greatly affected by the treatment of the insecticides.