The chromosomes of Phyllobius longicornis Roelofs collected from three localities in Hokkaido were studied in male germ line. The present species showed two forms which differ in their chromosome number: 10+Xyp and 11+Xyp. In Mt. Moiwa population, the occurrence of the former form is 84.4 per cent, while that of the latter is 15.6 per cent.
