Males perch on branches, surveying their territory and scouting for females. They will chase away intruders like other insects and sometimes small birds. Up until the end of May, Females lay fertilized eggs on leaves that are near a host plant, forcing newly hatched larvae to find their own host plant. Caterpillars feed on the leaves of elm trees, hackberry, nettles and false nettles. Their bodies are a mix of orange, red, black and white speckles depending on maturity. All are covered in fierce looking spikes that branch out with more spikes, resembling the spines of a barrel cactus. These spines and spikes change color as the caterpillar changes color: reddish body with red-orange spikes, black and yellow body with yellow spikes. Adults prefer drinking from rotting fruit, sap, dung and carrion juices, but will settle for flower nectar if these more pungent food sources are not available.
Some adults will migrate south to avoid cold winters, others hibernate in shelters up north. They can be found in cities, parks, suburbs, gardens, and meadows.