Natural History

The Painted Lady begins its life cycle as an egg that is the size of a pin head. Eggs are pale green and are laid on thistle, mallow, or hollyhock leaves. The incubation period is 3 to 5 days at which time a caterpillar emerges. The caterpillar grows to 1.25 inches in length and is purple or black with yellow/green stripes with long spines on each segment. It builds a silky, webbed nest as it feeds, usually eating thistle, mallow, malva, hollyhock, sunflower, or canola. As the larva grows, it sheds its skin (molts). When the caterpillar has grown to the right size, it pupates. It hangs upside-down from a leaf or branch, and attaches itself with a single silken string. An adult butterfly forms from the caterpillar, whose internal structure changes completely. The chrysalis becomes almost transparent when the butterfly is about to emerge. An adult will emerge about 7 to 10 days after the chrysalis has formed. When an adult emerges from the split chrysalis, it hangs upside down and pumps blood into its four wings, inflating them, then it waits for its delicate wings to dry. It can fly a few hours after emerging. 
 

The painted lady prefers nectar from plants 3-6 feet high, especially thistles. Males perch on shrubs and hilltops and patrol during the afternoon for females that are ready to mate. Females lay eggs one at a time on the tops of host plant leaves.