Post Tara Roth, Ph.D.

Enjoying the Warm Weather? So Are the Mosquitoes

Have you ever wondered why you don’t see many cold blooded animals, like reptiles or insects, in frozen regions of the world? Heat allows animals to run, jump, and think and mosquitoes are no exception. The warmer the temperature (up to a point), the more aggressive and hungry they get. They also reproduce much faster which means that surges in temperature can mean big surges in mosquito numbers.

Just like warmth is good for animals it’s also good for viruses. Normally, it can take a while for West Nile virus to move through the body of the mosquito and prepare to be injected into a new host (called the Extrinsic Incubation Period) but the warmer it gets, the faster the virus can move into position. Warm weather and drought conditions have been correlated with outbreaks of West Nile virus in birds which means a higher risk for human disease during the summer months. This means that the early warm weather currently in San Mateo County could lead to a busy season of surveillance and mosquito control to prevent disease cases.

At the District, we monitor mosquitoes, test dead birds and target mosquitoes in the larval stage to stay ahead of West Nile virus. Residents also need to take action to limit mosquito breeding on their property. Always check the area under and around your home for standing water and dump or drain if possible. If you cannot remove the water or notice a high number of mosquitoes near your home, please report it to the District so we can help keep the risk of diseases and nuisance mosquitoes low in San Mateo County.

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