Smerinthus tokyonis Matsumura, 1921, Thousand Insects Japan (Additam.) 4: 751. Type locality: Japan: Honshu, Tokyo.
A rare montane species.
Japan: 14.iv (Honshu, Ibaraki Pref.); 25.iv-21.v (Honshu, Kanagawa Pref.); 8-9.v (Honshu); 18.v-29.vii (Honshu); 6.viii-4.ix (Hokkaido, Nari-gawa); 13.ix (Honshu, Yokohama).
The peak of emergence appears to be in June/July, but individuals can be met with from mid April to mid September, indicating a partial second brood in some years.
LARVA: Very similar to that of Smerinthus ocellata (Linnaeus, 1758), but smaller. Basic body colour apple-green, with seven yellow oblique lateral stripes, that extending down from the lilac-blue horn being very pronounced and more white.
Larval hostplants. Apparently confined to Enkianthus campanulatus (Ericaceae).
Tachinidae: Exorista sorbillans (Wiedemann).
Japan: Southern Hokkaido (Nari-gawa); Honshu (Tokyo; Kita-Karuisawa; Gozaishodake; Karuizawa; Bushi; Mitsumine; Kiyosato, 1300m; Fujisawa; Yokohama; Yabuki; Toyama; Osaka); Shikoku; Kyushu (Miyasaki; Nagasaki Pref.).
The distribution of this species in Japan is patchy and restricted to certain montane areas. On Honshu, the only confirmed records are from the Prefectures of Fukui, Toyama, Kanagawa, Ibaraki, Fukushima, Chiba, Gifu, Aichi, Mie and Miyagi.
Endemic to Japan.