Magical sight’: Mass insect migration in European mountain pass

Researchers have documented one of nature’s great migrations – over 17 million insects annually passing through a mountain gap on the France-Spain border. A study found that at peak times, over 3,000 insects per meter moved through the Pass of Bujaruelo every minute, with 90% being marmalade hoverflies. Though insect numbers have declined, the migration remains an “amazing” spectacle to witness in September-October, especially on sunny days.