11:46 a.m. May 25, 2023: An earlier version of this story incorrectly stated Rudi Mattoni was a professor at UCLA. He was a lecturer. His 1994 survey was also not funded by the Urban Wildlands Group.

Longer and warmer autumns resulting from climate change may reduce the number of butterflies that emerge the following spring. Many butterfly species are declining due to rising global temperatures, ...

I talked about your question with my friend Allan Felsot. He’s an insect scientist at Washington State University. He told me cocoons are mostly silk. But they’re usually made by moths. A butterfly ...