The Aedes aegypti is a species of mosquito that people like Tim Moore, district manager of a mosquito control district on the Western Slope of Colorado, really don’t want to see. Now, an old residential neighborhood in Grand Junction, Colorado, has emerged as one of the latest frontiers for this troublesome mosquito. The city, with a population of about 70,000, is the largest in Colorado west of the Continental Divide. In 2019, the local mosquito control district spotted one wayward Aedes aegypti in a trap. Moore, the district manager, figured they’d caught a hitchhiker and that the harsh Colorado climate would quickly eliminate the species.