Why can't you see white butterflies in autumn?

Living in the state of pupa. Butterfly is a kind of temperature-changing animal, which is very sensitive to climate change. The life activities of butterflies are influenced by temperature changes. Butterflies overwinter as larvae or pupae, and prepare to pupate in autumn. Butterflies, commonly known as "butterflies, collectively referred to as arthropods, Insecta, Lepidoptera, Hymenoptera", have more than 18500 species all over the world, distributed in America, with the most species in the Amazon River basin.