PHOTOSYNTHESIS: Monarch Migration

Monarch butterflies – the fourth generation of those that initially began returning to northern states this spring – will soon begin migrating up to 2,000 miles to their overwintering grounds in Mexico. This migration will continue through the fall, with the last monarchs arriving at their overwintering sites in early December. This generation of migrators differs from the others in that it is the longest – both in terms of distance and time – and the butterflies do not mate and reproduce during the migration. Photo by Collin Massad.