In 1861, yellow fever struck the mississippi valley, hitting memphis, tn, most forcefully. half of the citizens fled and one-quarter of the remaining population died. historical records indicate that the epidemic ceased only after winter frosts arrived. why did the frost stop the epidemic? could yellow fever epidemics reappear in the u. s.?

Yellow fever is an illness produced by a zoonotic virus called Flavivirus. The vector of this virus is the mosquito called Aedes aegypti. Is known that the life of insects is affected by the environment temperature afecting their metabolism or ability to move. The lower temperature limit for Aedes aegypti is around 10 °C, a temperature below which mosquitoes become torpid and unable to move. During the winter frost in the winter frost the temperatures were less than 3,33 °C, so the mosquito Aedes aegypti couldn't survive at this temperatures.

x would be the most and the least would be y because there are more fruit   and seeds than flock z has insects