About Hypena crassalis (Fabricius, 1787)
Technical description and variation: This species has a wingspan of 25–30 mm, and forewing length of 14–16 mm. For the forewing, the basal two-thirds are dark chocolate brown, bounded by a pale outer line. This outer line is oblique and concave outwards to vein 5, strongly angled at vein 5, then sinuous inwards to the inner margin beyond the middle, meeting on vein 1 an oblique line running from the base of the median vein. The area below this line is pale with bright brown suffusion in males, and chalk white with faint discoloration in females. The terminal area is grey in males and chalk white in females. The subterminal line consists of interrupted fuscous lunules tipped with white in males, preceded by brown suffusion; in females, it is only a row of dark spots. There is an oblique thick brown streak extending from the apex, a row of black triangular terminal spots, a dark dot in the cell, and a lunule at the end of the cell. The hindwing is dark brownish fuscous with a ruddy tinge in males, and greyish white or pale fuscous in females. The aberration terricularis Hbn. is a nearly black form of the male with a small number of white terminal markings.
Distribution: This species is found across almost all of Europe, excluding the extreme southern and extreme northern regions of the continent. Its range extends east to Armenia and southern Russia.
