The mourning cloak is the longest lived butterfly of North America, at least in Canada because it happens that it makes only one generation.

Five days as an egg, three weeks as a caterpillar, 12 days as a chrysalis and the rest of the year it's a butterfly and hibernates, so it's an adult almost 11 months.

The female lays her eggs around a small branch of either a willow tree or a poplar or an elm tree or other decideous trees.

The caterpillars are gregarious meaning they all keep together.