Highlight mine. This is my understanding as well. As I understand it, the development of the malaria protozoa is hinged on the temperature of the host mosquito. The protozoa requires a constant temperature of >68F (I think) to mature at it’s fastest rate. If colder, it takes longer, and the mosquito will live out it’s 14-day life cycle and die before the malaria protozoa can mature (and then infect the human host). This is why malaria occurs mainly in the tropics.
I may have misstated some of that, but I am sure someone smarter will be along shortly to remedy my mistakes.