Aedes Aegypti Mosquito, Which Carries Dengue, Couldn't Survive In The Rockies. Now They're Thriving In Western CO.

It can carry life-threatening diseases. It’s difficult to find and hard to kill. And it’s obsessed with human blood. 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. “Boy, they are locked into humans,” Moore said. “That’s their blood meal.”

This mosquito species is native to tropical and subtropical climates, but as climate change pushes up temperatures and warps precipitation patterns, the Aedes aegypti—which can spread Zika, dengue, chikungunya and other potentially deadly viruses—is on the move. It’s popping up all over the Mountain West, where conditions have historically been far too harsh for it to survive. In the last decade, towns in New Mexico and Utah have begun catching Aedes aegypti in their traps year after year, and just this summer, one was found for the first time in Idaho.

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. It was odd, but the mosquitoes had already been found in Moab, Utah, about 100 miles to the southwest. Moore, the district manager, figured they’d caught a hitchhiker and that the harsh Colorado climate would quickly eliminate the species.

EDIT

The team bought different traps and adjusted their techniques to hunt for the mosquito. Scientific literature and mosquito researchers told them the effort was bound to be pointless. It was unlikely the mosquito would make it through the winter. Then, the results started coming in. In 2024, the first year of the Aedes aegypti surveillance program, the district caught 796 adults and found 446 eggs. These mosquitoes weren’t just surviving in Colorado—they were thriving.

EDIT

https://insideclimatenews.org/news/10112025/colorado-invasive-dengue-fever-mosquito/