Finlay continued his work in the 1870s. He was the first to come up with the idea that a mosquito was a carrier for a disease that causes yellow fever. He discovered that the spread and cause of yellow fever was from a mosquito. The mosquito would bite a person with the disease and would then bite and infect a healthy person. A year later Finlay identified the mosquito of the genus Aedes as the insect transmitting yellow fever. His research led to the control of the mosquito population as a way to control the spread of the disease.