The piece first appeared on Inside Climate News as part of the Climate Desk initiative. The Aedes aegypti mosquito is capable of transmitting serious diseases, is challenging to find and eradicate, and shows a particular preference for human blood. This mosquito, which flourishes in tropical and subtropical regions, is currently expanding its range due to climate change. It has been observed throughout the Mountain West, including locations in New Mexico and Utah, and recently in Idaho. In Grand Junction, Colorado, this mosquito has emerged as a new difficulty in an established residential area. Grand Junction, housing around 70,000 residents, is the largest city in Colorado west of the Continental Divide. In 2019, the local mosquito control district recorded the presence of an Aedes aegypti in one of their traps. Initially deemed an anomaly, the district manager, Tim Moore, believed that the Aedes aegypti would not endure the severe climate conditions. Nonetheless, the species had already been identified in Moab, Utah, close by. Moore originally regarded the discovery as trivial, but the current presence of these mosquitoes now necessitates heightened investment in new traps and personnel in Grand Junction. Photograph by Isabella Escobedo.