Why Mosquitos Bite Some People and Not Others

Science explains one of life's great mysteries. Plus! A natural remedy to keep you insect-free all summer

Why are some people so much more attractive to mosquitoes than others? And what can you do about the pesky little bloodsuckers, especially if you don’t want to resort to DEET? (DEET, while effective, is also weakly neurotoxic in humans.)

To start, there are some 150 different species of mosquitoes in the United States, and they differ in biting persistence, habits, ability to transmit disease, and even flying ability.

Mosquitoes of the genus Culex are painful and persistent biters and they will gladly fly into your house to bite you. They bite at dusk and after dark, and they can spread West Nile virus. On the upside, however, they are not strong fliers and won’t fly long distances from where they hatched. And, they’d prefer to bite a bird than a human. A common Culex species in the U.S. is C. pipiens, the Northern House mosquito.

Then there’s the genus Aedes, which includes A. aegypti and A. albopictus, the Asian Tiger mosquito. The former is not a problem in the U.S.; the latter is. Both can transmit Yellow Fever and Dengue Fever. Aedes mosquitoes feed early in the morning as well as at dusk and into the evening. They might also bite you during the day if it’s cloudy or if you wander into a shady place. Fortunately, they probably won’t enter your house – but they do prefer biting mammals like humans over other animals, and they are very strong fliers.

One other notable genus of mosquitoes areAnopheles mosquitoes. They are the ones responsible for transmitting malaria. In the U.S., that mostly means A. quadrimaculatus, which lives in the central and eastern U.S., as far north as southern Canada.

But if we have Anopheles mosquitoes, then why don’t we have malaria? The answer, in part, is due to climate. According to Andrew Githeko, a Kenyan scientist who studies malaria, malaria only occurs in places where the average temperature is above 18C (64.4F). Below that, the mosquito dies before the parasite matures, and this prevents transmission. In Kenya, he discovered malaria already moving into new areas as the climate warmed. Fortunately, malaria is not endemic to the U.S. as it is in Kenya. And if the U.S. lacks a base of humans and mosquitoes carrying the parasite, then that prevents the spread of the disease.

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