Usually migration, or just because they got caught by the wind/hot air bubble. It's not like a fall from any height can harm them anyway. https://www.nature.co

Usually migration, or just because they got caught by the wind/hot air bubble. It's not like a fall from any height can harm them anyway. https://www.nature.com/news/2010/100204/full/news.2010.54.html https://www.nature.com/news/2010/100204/full/news.2010.54.ht... https://www.npr.org/sections/krulwich/2011/06/01/128389587/look-up-the-billion-bug-highway-you-cant-see https://www.npr.org/sections/krulwich/2011/06/01/128389587/l...