We conducted field and laboratory observations of the life histories and fungal hosts of the darkling beetle, Platydema nigroaeneum Motschulsky. P. nigroaeneum, a fungivorous tenebrionid beetle, was a widespread inhabitant of fungi on deciduous trees (Quercus, Salix, Alnus and Carpinus etc.) in Korea. Development from egg to adulthood took 4～11 months in nature and about 66 days in the laboratory at 25.5～26.1℃ and 63.5～64.5% relative humidity. Both larvae and adults overwintered in their host fungi or beneath the bark of the host tree near the host fungi. Sporophores of Coriolus Qu?let, Bjerkandera Karst., Daedaleopsis Schroet. and Merulius were common feeding and breeding sites in Korea.