Each autumn, monarch butterflies migrate thousands of kilometres across North America to warmer regions.

The longer version

Seasonal migration lets these butterflies escape cold they cannot survive as active adults. Rather than one individual making the whole journey, successive generations pass it along, with the autumn cohort entering a restful state that stores fat and delays reproduction until spring.

Navigation appears to combine a sun-based compass with an internal sense of time, adjusted so the flight angle stays roughly steady through the day. Clustering on trees in sheltered valleys moderates temperature and moisture, letting them wait out winter. Their caterpillars feed on milkweed, which makes the adults unpleasant to many animals that might otherwise eat them.

Where this entry sits

This collection gathers small wonders from the world of ants, bees, butterflies, beetles, and spiders. Expect surprising details about swarms, silk, and metamorphosis, plus the strange everyday abilities of creatures small enough to fit on a fingertip. The full list sits on the Insects and Spiders page, where every entry is listed in order.