Pheromones of C. herculeanus and C. ligniperdus show significant qualitative differences, which evidence their specific separateness. C. herculeanus and C. ligniperdus are closely related allopatric species. On the limits of their distributional areas, in the places where they meet, the species are environmentally and phenologically isolated. In the mountains isolated, relict populations of C. herculeanus occur within distributional limits of C. ligniperdus. They show wide ecological tolerance and on the limits of their areas both species inhabit the same habitats. Also morphological differences between them partially evanesce (var. herculeano-ligniperda For.).