Several cities across Europe are replacing conventional white streetlights with red or orange-red lamps to reduce light pollution and protect nocturnal ecosystems, coinciding with the close of International Dark Sky Week. Gladsaxe (a municipality north of Copenhagen, Denmark) pioneered the approach near a large bat colony, with similar schemes now operating in Metz, France; Worcestershire, England; Germany; the Netherlands; and Belgium — and most recently in Odense, Denmark's third-largest city. Bats, which consume vast quantities of insects nightly and help farmers reduce reliance on chemical pesticides, are blinded by white artificial light but can navigate under red light; experts say the switch also uses less energy and requires less maintenance, making it both an ecological and economic gain.