Pat Vigil, a Carbon County mosquito abatement employee, throws granules containing larvacide into a stagnant water pool in Miller Creek. The pool often serves as a breeding ground for mosquitos. Many county agencies are preparing for the onslaught of mosquitos, with the up and running date for as much control as possible being May 15. While numerous types of mosquitos spread different diseases, two species that appeared late in the summer last year in the Carbon area carry the West Nile virus. The virus accounted for many human deaths in Colorado last year. Officials warn residents that, come the middle of May, people should take clothing and repellent measures to ward off the insects from dusk to dawn, the time when the particular species tends to bite victims.