It appears now well-known that Bena fagana (FABRICIUS)(=prasinana auct.), a common Eurasian species, produces the second generation moth in different form in the warmer regions of Europe. It had been called under various names as distinct, till OBRAZTSOV (1943, 1950) published a conclusion. The oldest name applicable to the form is fiorii COSTN. (1911), of which hongarica WARREN (1913) and hispanica FERNANDEZ (1931) are synonyms. It has relatively shorter and broader forewing than in the typical or vernal form and only two median bands on it in both sexes. The moths known to us as Bena japonica (WARREN) is apparently the Japanese representation of the aestival form of fagana, occuring in major part of Japan in July towards August except in Hokkaido, where occurs only the typical form. In Japan and its neighboring areas there occurs another couple of species of the genus, named respectively kraeffti GRAESER and sylpha BUTLER. The latter form showing only two oblique median bands is, though peculiar in having purely white hindwing in both sexes, here concluded to represent the aestival form of the former appearing in early April to May. The fact was confirmed by breeding larvae obtained from ova laid by female kraeffti in spring. This species, for which the specific name sylpha BUTLER is the earlier one, is a resident of the lowlands shrubs, feeding preferably on the leaves of deciduous oak, Quercus acutissima and Q. serrata, in the area west of central Honshu. The synonymies will be given as follows. Bena fagana (FABRICIUS, 1781)=japonica WARREN, 1913, syn. nov. Bena sylpha (BUTLER, 1879)=kraeffti GRAESER, 1888, syn. nov.=magnifica LEECH, 1890, syn. nov. The difference of male genitalia between the two is slightest, but in female genitalia the shape of sclerotization of bursa copulatrix at near orifice to ductus bursae differs enough to separate them.
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