In an analysis of mosquito sampling across 20 years in Connecticut, mosquito populations—such as those of Culex pipiens, a primary vector of West Nile virus—were often correlated at sites 10 kilometers apart and sometimes as far as 40 kilometers apart. But the same data showed the presence of mosquito-borne viruses rarely correlated across distances more than 5 kilometers, complicating potential approaches to managing mosquitoes and the risk of vector-borne disease. (Photo by Ary Farajollahi, Bugwood.org)