Insect fauna on flower-heads of two Asteraceae species in Hokkaido
Niwa, Shin Ichi
Bulletin of the Higashi Taisetsu Museum of Natural History 24: 9-15
Floral visitors on flower-heads of two Asteraceae species, Cirsium kamtschaticum subsp. kamtschaticum and Ligularia hodgsonii, were investigated in Rishiri island and Taisetsuzan mountains, Hokkaido. In the observation, insects were recorded as bumblebees, wasps, ants, other hymenopteran (small bees), dipteran, lepidopteran, coleopteran and other arthropods (e. g. spiders). If possible, family or species name were recorded. C. kamtschaticum subsp. kamtschaticum have several large and downward flower-heads per stem. L. hodgsonii have several large and upward flower-heads per stem, and each flower-head has several large ligulate flowers. On C. kamtschaticum subsp. kamtschaticum in Rishiri, many bumblebees, e. g. Bombs yezoensis, were observed. But, the other insects were not observed, because of strong wind and low temperature. On L. hodgsonii in east Taisetsuzan mountains, many dipteran and lepidopteran, and a few bumblebees were observed. In Rishiri, only a few bumblebees were observed, because the end of flowering time was near there.