×

August is peak mosquito season, and California’s in a fight against disease some carry

August is peak mosquito season, and California’s in a fight against disease some carry

Bugged out

We all love to spend the summer months outside, but the warmest months also bring out more bugs, some of which may carry nasty diseases.

According to the Centers for Disease Control and Prevention, over 200 types of mosquitoes live in the continental United States and U.S. territories and about 12 types spread germs that can make people sick.

In California, there are approximately 50 kinds of mosquitoes with about six that carry harmful diseases such as West Nile virus, Zika, dengue and yellow fever viruses. Some infect horses, birds and house pets.

You can open a PDF from the California Department of Health that lists the dangerous mosquitoes in California here.

Some studies claim mosquitoes are the world’s deadliest animal and estimates say they kill 700,000 people a year, with most in Sub-Saharan Africa.

How they find us

Body odors, exhaled breath and body heat all alert mosquitoes to a person’s presence. The bugs pick up scents through olfactory neurons on their antennae—they can smell body odor from nearly 200 feet away —and use body heat to zero in on their target.

Recent studies have shown more mosquitoes seemed to prefer people whose scent contained a blend of carboxylic acids, the oily secretions that hydrate and protect our skin. Two of those carboxylic acids are also found in Limburger cheese, known to lure mosquitoes.

Also see: What makes you a mosquito magnet? Some people can’t escape the pesky but dangerous bites

What keeps them away

Mosquitoes are less likely to buzz over to scents with lots of the chemical eucalyptol, found in plants like sage and eucalyptus trees. The EPA has a list of recommended repellents including DEET, Picaridin, IR3535 and others with eucalyptus oils.

The EPA has a webpage on how to find the right repellent for you here.

In addition to repellent, wearing loose-fitting long pants and sleeves while outdoors is helpful to prevent bites and so are screens on windows and doors.

Mosquito control

Related Articles

Environment |


West Nile virus found in mosquitos and birds in Contra Costa, Napa counties

Environment |


Person tests positive for West Nile virus in Santa Clara County

Environment |


Map: Mosquito spraying in Santa Clara County after West Nile discovery

Environment |


Map: Palo Alto, Stanford neighborhoods to be sprayed after West Nile mosquito discovery

Mosquito control in California is conducted by approximately 80 local agencies, including mosquito and vector control districts, county environmental and health departments, and county agriculture departments.

Bats, birds, frogs and fish eat mosquitoes but in some areas of standing water they barely put a dent in the mosquito population. That’s when chemical control is used.

Pesticides have been applied to kill mosquitoes in California for over 70 years. Larvicides are also applied to the water from trucks, and sometimes aircraft.

One of the more recent methods of abatement is called Sterile Insect Technique: Irradiation. Large numbers of mosquitoes are raised in a lab.

Male mosquito pupae are separated from female pupae. Males are irradiated, using ionizing radiation, to make them sterile. Male mosquitoes are bred and sterilized using the same radiation found in X-rays. Males are then regularly released to mate with wild females. The resulting eggs will not hatch.

You can find more details on Sterile Insect Technique at the Orange County Department of Health’s vector control website here.

Counties and cities are doing their part, but individuals need to help too. Most counties in California have a hotline or website where you can report issues with mosquitoes or areas of standing water (empty swimming pool) that can present a problem.

Here’s how California is doing with the two worst mosquitoes that spread disease and case counts:

You can keep up with West Nile virus case counts across the state at westnile.ca.gov.

Source: University of Kentucky, College of Agriculture; Centers for Disease Control and Prevention, California Department of Public Health, Orange County Department of Public Health, WestNile.ca.gov, The Associated Press