The Wall Brown (Lasiommata megera) is a medium-sized butterfly (wingspan 36–50mm) with distinctive orange-brown wings, dark brown, zebra-like markings, and white-pupilled spots. Famous for basking on sunny, bare, stony areas (walls, paths, coastal cliffs), they have experienced a severe population decline in the UK and are now mostly found along the coast.
Key Facts About the Wall Brown
Appearance: Males are smaller and darker with a prominent, dark brown scent stripe (sex brand) on their forewings. Females are larger, with brighter orange coloring.
Behavior: They are rapid fliers, often seen fluttering close to the ground, but frequently bask on rocks, sunny walls, and dirt paths.
The imago flies from April to October in two or three generations depending on locality and altitude. The larva feeds on grasses in the genera Festuca, Bromus, Deschampsia, Poa, Dactylis and Brachypodium.
"The egg is pale green when first laid, and in shape it is almost spherical, but rather higher than broad; it is finely ribbed and reticulated, but unless examined through a lens it appears to be quite smooth. The caterpillar when full grown is whitish-green, dotted with white. From the larger of these dots on the back arise greyish bristles; the three lines on the back (dorsal and sub-dorsal) are whitish, edged with dark green; the line on the sides (spiracular) is white, fringed with greyish hairs; anal points green, hairy, extreme tips white. Head larger than the first ring (first thoracic segment), green dotted with white and hairy, jaws marked with brownish. The chrysalis is green, with yellow-tinted white markings on the edge of the wing covers and ridges; the spots on the body are yellowish, or sometimes white. Occasionally the chrysalids are blackish, with white or yellow points on the body". (South 1906)
Life Cycle & Habitat: They are found in hot, open, rocky environments, including coastal paths, quarries, and disused railway lines. They overwinter as caterpillars (larvae).
Broods: There are usually two to three generations per year, appearing from April through October.
Diet: Caterpillars feed on various grasses, including tor-grass, bent, and fescue species.
Conservation Status: This species has seen a massive, rapid decline (>80% since 1976), particularly inland.
They are sometimes confused with the Gatekeeper or Speckled Wood but are distinguished by their intense orange color and preference for rocky, open, barren habitats.
