Identification
Fresh specimens show scattered raised white scales on the forewings but the white scales can disappear with wear.
This is the only eastern species in the genus with FW length >1 cm, a robust thorax, and directly upward-pointing palps that flies in the summer. Some A. mora may have palps that appear upward-pointing in some photos, but A. mora is easy to identify from its flight season (September-October vs May-August for arcanella). These images show the robust thorax (much thicker than the head) and distinctive palps well:
Genitalia:
Remarks
This is a common eastern species that has been mostly confused with Acrolophus popeanella.
Internet References
Moth Photographers Group – images of live and pinned adults