Yellow Fever Mosquitoes

The non-native insects taking up residence in SJ County

There are two types of non-native mosquitos on the CDC’s radar this year, Aedes aegypti (the yellow fever mosquito) and Aedes albopictus (the Asian tiger mosquito). Both mosquitoes can live and reproduce in California, however the prevalence of the yellow fever mosquito is much greater, especially in Northern California, and those who live in San Joaquin County should brush up on their knowledge of these pesky pests.

What to Know:

The yellow fever mosquito, like the Asian tiger mosquito, is a small black insect with white stripes on its back and legs. The stripes appear to create a harp pattern on its mid-body and bands on its legs. One of the best ways to distinguish this mosquito from other types is by its daytime biting habit because most mosquitos only bite at night. These bites typically occur on ankles  and elbows. “The Aedes aegypti is very difficult to control. It glues individual eggs to the sides of containers like flower pots and small sources of water around homes. Even a discarded bottle cap with water is enough for their development,” says Aaron Devencenzi, public information officer for SJC Mosquito & Vector Control District. “The eggs are resistant to drying out and can survive without water for many months in the egg form, until water covers them.” Keeping properties clean and disposing of containers that can hold a teaspoon of water or more can help.

The Invasion:

Yellow fever mosquitos were first found in Stockton in summer 2019. Resident complaints led SJC Mosquito to deploy elimination techniques that have helped to control the population. They often live in urban areas both indoors and outdoors.

A Potential Health Threat:

“Although we have Aedes aegypti in San Joaquin County, we have not found the presence of any virus in these mosquitoes,” Aaron says. That being said, these mosquitoes are of concern because of how invasive they are. In addition to being an annoyance, both the yellow fever mosquito and the Asian tiger mosquito have the ability to carry diseases such as Zika, dengue, chikungunya, yellow fever, and others.

How can I avoid mosquito bites?

*Information provided by

  • Apply a repellent that contains DEET, picaridin, IR3535®, or oil of lemon eucalyptus.
  • Wear protective clothing, such as long- sleeved shirts and pants.
  • Check and repair all window and door screens to keep mosquitoes out of your house.
  • Minimize outdoor activities if mosquitoes are active.
  • Call the District to report daytime biting mosquitoes or significant numbers of mosquitoes.

Report Sightings:

SJC Mosquito & Vector Control District
(209) 982-4675

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