In the early 1980s, Aedes albopictus, a mosquito species native to Southeast Asia that spreads dengue fever and yellow fever, turned up deep in the American South. Though there were no reported disease outbreaks, epidemiologists were still worried, especially when huge swarms arrived in Houston. The so-called Asian tiger mosquito had clearly gained a foothold in the U.S., but no one knew how it had gotten there. So medical entomologist Paul Reiter headed to the city, situated near the Gulf of Mexico, to search for larvae (and answers) in containers of standing water — especially inside discarded, used tires. There, a chance encounter along a road on the outskirts of town put Reiter on the trail to solving the mystery.