After hatching, the eggs produce black caterpillars with small white spots and spiny bodies. They mainly feed on trees such as willow, elm, and poplar, so they usually do not cause major damage to vegetable or flower gardens.
The caterpillars eventually form a chrysalis and transform into dark butterflies with yellow-edged wings and blue spots. Mourning Cloaks can even survive winter by hibernating under bark, wood piles, or other sheltered places.
If you find the eggs or caterpillars, the article recommends leaving them alone rather than immediately using insecticide. If necessary, gently move caterpillars to a nearby tree or shrub and allow them to complete their natural life cycle.
