Invasive Aedes Mosquitoes
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Invasive Aedes mosquitoes, or “ankle biter” mosquitoes are small black and white striped mosquitoes that:
- Bite during the day, especially around the legs and ankles
- Can bite aggressively and multiple times
- Are most active in San Diego during summer and fall
- Breed indoors and outdoors
- Lay eggs in small containers of water
These mosquitoes will breed in backyards and even inside homes. When it is warm, they can go from egg to adult in less than one week!
Invasive Aedes mosquitoes are not naturally found in San Diego and were first found in the county in 2014. Some Aedes species, Aedes aegypti and Aedes albopictus, can spread viruses like Zika, dengue, yellow fever, and chikungunya. Aedes notoscriptus has also been found in the County of San Diego and can spread diseases including dog heartworm.
The map below shows where invasive Aedes mosquitoes (in yellow) have been found recently by the Vector Control Program.
Dump standing water
Invasive Aedes mosquitoes like to lay their eggs in small containers of standing water, often in your backyard. Even 1/4" of water is enough.
Their eggs can survive for months in dry containers. Then when water is added, they are ready to hatch. It takes about one week for them to grow in the water and turn into biting adults. If you are getting bitten, the mosquitoes are probably coming from somewhere close by.
Dump out standing water sources both inside and outside at least once a week! Check places like buckets, birdbaths, potted plant saucers, and children's toys. Use the mosquito prevention resources to get started.
Treat standing water
If you can't dump the water out, there are other options. You can add mosquitofish to backyard ponds, fountains, and unmaintained green pools. They are available free of charge from the Vector Control Program.
You can also use a mosquito larvicide which can be purchased at home and garden stores. Make sure to follow all instructions on the label.
Once you have dumped out standing water around your home, talk to your neighbors. When we work together, we can stop mosquitoes.
Choose an insect repellent containing an EPA registered, CDC recommended active ingredient such as:
- Deet
- Picaridin
- Oil of lemon eucalyptus (OLE)
- IR3535
- Para-menthane-diol (PMD)
- 2-undecanone
Always follow the directions on the label. Find the right insect repellent for you and your family using this guide.
Wearing long sleeves and pants in lighter colors can also help prevent bites.
Keep mosquitoes out by putting screens on windows and doors. Use a fine mesh to prevent the small Aedes mosquitoes from getting in.
Diseases like dengue, that are spread by Aedes mosquitoes, are rare in San Diego but more common in many places around the world. Most dengue cases in San Diego County are due to travelers returning from other parts of the world. However, in 2025, San Diego saw its first case of locally acquired Dengue, which means the person was infected in San Diego without traveling.
Dengue is spread through the bite of an infected mosquito. Prevent the spread of dengue by:
- Checking CDC travel advisories at your destination
- Wearing mosquito repellent while traveling
- Wearing mosquito repellent when you return from travel
- Contacting your doctor if you have been bitten by mosquitoes and develop symptoms such as fever, headache, muscle and joint pain, and rash
More information
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Preventing
Dengue Fever in Your Community
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Dengue
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CDC
Aedes Information
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