Biston sinuaria

Distinguished from other Biston species by the sinuous (wavy) pattern of the median lines on the forewings, which gives the species its name. Most similar to Biston robustum but with more irregular, less parallel wing lines. The discal spot is usually faint or absent. Genitalia examination may be required for definitive identification from closely related species.

Adults have broad, triangular forewings with wavy, irregular transverse lines creating a bark-like pattern. Wing coloration ranges from gray to brown with variable darker markings. Hindwings are paler with reduced patterning. Body is stout and densely hairy. Wingspan approximately 40-55 mm.

Deciduous and mixed forests, woodlands, and parklands. Associated with mature trees providing larval host plants and bark-matching camouflage for adults.

East Asia including Japan, Korea, and parts of China. Records also from the Russian Far East.

Adults fly from late spring through summer, with peak activity in June-July in temperate regions. Univoltine or partially bivoltine depending on latitude.

Adults are nocturnal and strongly attracted to artificial light sources. Daytime resting posture aligns wings flat against tree bark, enhancing cryptic camouflage.

Larvae function as herbivores on woody vegetation; adults serve as prey for nocturnal insectivores including bats and birds.

Occasional minor pest of ornamental trees; otherwise of limited economic significance. Sometimes encountered at porch lights.

• Biston robustumOverlapping distribution and similar bark-mimicking appearance; distinguished by more regular, parallel forewing lines and generally larger size
• Biston betulariaShares genus characteristics but has more uniform dark or pale morphs with less intricate patterning; European distribution with limited overlap

• BugGuide
• iNaturalist taxon