Observations on the common brown butterfly (Heteronympha merope) in the early 1900s in Australia using digitized specimens

The Common Brown butterfly, Heteronympha merope (Fabricius 1775), is a ubiquitous species from the family Nymphalidae, distributed across south-eastern Australia. Using online photographs of 33 digitized museum specimens provided by the Atlas of Living Australia, forewing length was found to be highly correlated with the total wing surface area (r = 0.962), indicating that this metric can be used as an accurate estimate of body size. No significant relationship was found between body size and environmental temperatures, latitude, or the year of collection (1902–1948). The size of females was higher between October and December compared to the rest of the year, while the size of males did not change. Collection of contemporary data on the body size of H. merope would allow the assessment of whether the body size of this species has changed over the past 70 years.