An invasive, day-biting mosquito that can potentially transmit dangerous viruses has now been found in Ojai, Ventura County Environmental Health officials said Wednesday.

The invasive Aedes aegypti mosquito, a black-and-white insect about the size of a pencil eraser head, has been establishing itself throughout Southern California for the better part of 10 years, according to Ron Ventura, supervising environmental health specialist with the Ventura County Environmental Health Division.

“It’s known as the ankle biter mosquito,” Ventura told the Ojai Valley News. “We’ve been receiving many complaints from residents all over the county, letting us know about this mosquito that’s been biting their ankles.”

Since its detection through surveillance and tracking in September 2020, the mosquito has spread west from Simi Valley, according to Ventura. “It’s made it to most cities in the county, and it’s definitely up in Ojai,” he said. “This year, we found two locations, in the eastern area of Ojai and in the Meiners Oaks area.”

The Aedes aegytpi mosquito has had a presence in Ventura County since September last year. Officials have previously found the aggressive insect in Simi Valley, Thousand Oaks, Westlake Village, Fillmore, Piru, Ventura, Oak View and Oxnard. It is capable of transmitting viruses including dengue, yellow fever, chikungunya and Zika, although no such transmissions have been documented in California, authorities said.

Aedes aegypti are small with a dark body and white stripes. Officials recommend residents dump out all sources of standing water, both indoors and outside, since the mosquitoes lay eggs near the water line of such containers.

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Unlike most native mosquito species, Aedes mosquitoes typically bite during the day, approaching low and behind their victim, and aggressively biting ankles and elbows. “The adult female is known to bite up to 20 times, even after it received a blood meal,” Ventura said.

And they adapt very well to houses and buildings, living both inside and out. “They like you and your home, unlike the native mosquito, where their hosts are birds and rodents and such,” Ventura said. “This mosquito finds you as their host, so they have adapted to live in and around your home.”

Even one mosquito in your home can create havoc, according to Ventura. “You’ll go to sleep and wake up in the morning and find all these bites all over your body. Mainly, your ankles,” he said.

As for how they got into Southern California, one theory is they originated in shipping containers holding bamboo plants, where eggs and larvae were found.

The female Aedes mosquito lays her eggs in standing water, in containers or on surfaces holding as little as a teaspoon of water. The mosquitoes breed in old tires, bird baths and unmaintained swimming pools. “So eliminating stagnant water around your home will prevent mosquitoes from developing in the first place,” Ventura said.

Larvae have been found developing on plants that hold water, such as bromeliads, bamboo and succulents. The mosquito can also breed on indoor plants and in aquariums, Ventura said.

The County of Ventura is asking residents to do source reduction — thorough, weekly inspections around their homes, eliminating any stagnant water they find. “We’re talking any stagnant water,” Ventura said, including potted plant saucers and rain gutters.

Residents who find mosquitoes in their home but don’t know where they’re coming from can call the Mosquito Complaint Hotline at 805-658-4310.

The Environmental Health Division will send out a trained vector technician who will inspect properties for mosquitoes. “If they do find them, we have door hangers that will alert neighbors and hopefully really get everybody together to do this source reduction,” Ventura said.

Aedes mosquitoes have the potential to transmit several tropical diseases, including dengue, the Zika virus and yellow fever. “Currently, these mosquitoes are just a nuisance in California,” Ventura said. “There has been no evidence of any local transmission here in California.”

Thousands of people, however, have become infected in other parts of the world, such as Mexico, Central and South America, the Caribbean and Asia. “If we have a traveler who went abroad to one of these areas where those diseases are endemic, they come back and they’re ill, there is the potential that if this mosquito is in the area, they could bite that individual and possibly have a local transmission,” Ventura said.

Residents can report day-biting mosquitoes to the county’s vector control hotline at 805-658-4310.