Tangle of Downed Oyamel Firs (IMAGE) Entomological Society of America Caption A tangle of downed Oyamel first shows the damage sustained in the Sierra Chincua overwintering area of the monarch butterfly in Mexico during a severe winter storm in March 2016. New analysis estimates 30-38 percent of the monarch butterflies there at the time perished in the storm. Credit David Kust/Entomological Society of America Usage Restrictions Maintain attribution. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.