Student Article

The Pyrenees witness a breathtaking insect migration every autumn.

A bug superhighway Every autumn, a remarkable spectacle unfolds in the Pyrenees as over 17 million insects migrate through a narrow 100-foot-wide (30-meter-wide) mountain pass on the border between France and Spain. A team of scientists has been monitoring this migration for four years, documenting the vast number and variety of insects heading south. Meet the travelers The insects, including marmalade hoverflies and cabbage white butterflies, embark on their journey from northern Europe, traveling south into Spain and potentially beyond for the winter. On peak days, the number of insects passing through the pass can exceed 3,000 individuals per three feet (one meter) per minute. Why this spot matters This mountain pass is a vital route for many migrating insect species, offering the easiest passage through the high mountains. Researchers now estimate that billions of insects migrate through the Pyrenees every autumn, highlighting the importance of this location for studying insect migration. Almost 70 years of research The origins of this research date back to 1950 when British ornithologists Elizabeth and David Lack first recorded marmalade hoverflies migrating through the mountains. In 2018, researchers revisited the same pass and were astonished to find that the migration was still occurring, with even greater numbers and diversity of insects.

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