Remains of invertebrates, especially insects, are frequently found in carnivores' faeces. Invertebrates are generally restricted to a given area and many factors such as landuse pattern, vegetation structure or even moisture can separate different groups; thus, invertebrates can be used as bioindicators. Forty-five samples of marten and fox scats were analysed for the presence of insect species. Thirty insect species — which were expected to be found — were identified. Canonical correspondence analysis indicated that the factor ‘species’ (i.e., marten and fox) was the main factor determining invertebrate species variation. Redundancy analysis allowed us to identify invertebrate ecological groups associated with these two carnivores. Martens prefer nest-building insects as a supplementary source of food and mainly forage in meadows, whereas foxes foraged in forest with high volumes of insects as well as necrophages. Martens preferred smaller, while foxes preferred lager insects. We conclude that insects found in faeces might play an important role in understanding food and habitat relationships between sympatric predators.