There is another species of mosquito that is most often associated with outbreaks of EEE in horses and humans. This is a large black and white mosquito that looks for blood around dusk. Cokes have a geographic distribution similar to C. melanura, but rather than breed in wooded swamps, they breed in cattail or grassy marshes that have a mucky bottom. These types of marshes are often next to the swamps that produce C. melanura. The species of Aedes involved differ from area to area.
Cokes are the only other mosquitoes found throughout the range of EE in the United States.
While cokes and Aedes can fly more than five miles, EEE generally does not occur in areas where there are not C. melanura. Of course, mosquitoes also can blood feed on birds other than wild song birds. Birds that are not native to the U.S., such as ring-necked pheasants and starlings, and some native birds, such as whooping cranes and sandhill cranes can become ill, and many die. Die-off's of exotic birds, particularly pheasants, often precede outbreaks of EEE in humans and horses. Unlike wild birds, infected horses and humans normally do not develop high enough concentrations of virus in their blood to infect mosquitoes.