Wild Barcelona: Butterfly brawlers

In early autumn the two-tailed pasha— the sultan of butterflies—is on the wing. To view this flamboyant, hard-fighting, hard-drinking creature—a member of the manly African Charaxes family—head for Collserola Park, where the strawberry trees grow.

Brown and orange on top, the pasha’s underwings are a rich tapestry of chocolate and grey. As well as the striking markings and a twin set of tails, the pasha’s attitude and sheer physical presence also impresses; this is the largest butterfly in Europe.

The males are fearless defenders of their territories, often seen perched on a post or tree, ready to launch an attack on intruders, people included. You might experience an intense flutter of wings about the head if you stray into their zone.

When not brawling, the two-tailed pasha is looking to get liquored up. Drawn irresistibly to rotten fruit, such as figs over-ripened in the hot sun, it avidly sucks up the fermented juices. Lepidopterists prepare rotten bananas laced with rum to coax the butterflies in for a close-up.

In October the females are flying fast among the strawberry trees, as they look for a likely place to lay their eggs. The leaves will nourish the caterpillars, who make their silken beds in the tree.

The strawberry tree is a Mediterranean evergreen and it’s easy to locate, festooned with glowing scarlet berries. Biting through the slightly gritty surface you find a soft yellow center, ideally with an acidic tang. Taste varies from tree to tree and year to year—those of the Garraf region produce the best I’ve ever tried, with the right balance between sweet and sharp.

Immortalized in the Madrid coat of arms, which pictures a bear reaching up for the fruit, the strawberry tree brings a festive air to Collserola in autumn. Before the red berries disappear, clusters of white bell-like flowers will also emerge.