SoCal Mosquito Surge: Itchy Bites & Invasive Species Blamed

March 3, 2026 Ananya Mittal - World Editor

Southern California residents are reporting a noticeable increase in mosquito activity, even during the typically cooler winter months, with many experiencing itchy bites – often around the ankles. While a surge in mosquito complaints isn’t unusual, experts at vector control districts point to a combination of unseasonable weather and the growing presence of invasive Aedes mosquitoes as key factors driving the current uptick.

The Rise of the “Ankle Biters”

These aren’t your grandmother’s mosquitoes. The mosquitoes causing the most trouble are Aedes aegypti and Aedes albopictus, often called “ankle biters” because of their tendency to target the legs. Unlike native mosquito species, Aedes mosquitoes are aggressive biters and can transmit diseases like dengue fever, chikungunya, and Zika virus. They were first detected in Southern California in 2011 and have been steadily expanding their range. The San Gabriel Valley Mosquito & Vector Control District details how these mosquitoes thrive in the region’s climate, breeding year-round in stagnant water.

What sets Aedes mosquitoes apart is their unique breeding habits. They lay “time-capsule eggs” that can survive for months in dry conditions, hatching when exposed to water – even a small amount. This means that containers like flower pots, bird baths, and even discarded tires can become breeding grounds. They also seek shelter in dense vegetation, like ivy and bushes, protecting them from sun and wind.

Why Now? Weather and Invasive Species

The recent surge in mosquito activity is likely linked to the unusually warm and wet weather Southern California has experienced. These conditions create more opportunities for standing water, accelerating the mosquito life cycle. The California Department of Public Health notes that invasive Aedes mosquitoes are particularly well-adapted to urban environments and can breed in small containers, making them difficult to control.

The increase isn’t simply a matter of more mosquitoes; it’s a matter of different mosquitoes. As the SGVMVCD explains, there are now more species of mosquitoes present in Southern California, and the invasive Aedes mosquitoes bite more aggressively than native species like Culex mosquitoes. This increased aggression can make even short periods outdoors uncomfortable.

Understanding the Risks: Disease Transmission

While the majority of mosquito bites are simply irritating, the presence of Aedes mosquitoes raises concerns about the potential for disease transmission. These mosquitoes are capable of carrying and spreading viruses like dengue, chikungunya, and Zika. Currently, there are no widespread outbreaks of these diseases in Southern California, but the risk is present, particularly for travelers who may have been exposed in other regions. The Sutter-Yuba Mosquito & Vector Control District is actively monitoring for these invasive species and implementing response plans to mitigate the risk.

It’s important to remember that only female mosquitoes bite, as they require the protein in blood to produce eggs. A female mosquito typically lives for about two months, during which time she can lay multiple batches of eggs.

What Can You Do? Prevention and Control

Vector control districts are working to control mosquito populations through surveillance, larval control (targeting mosquito larvae in breeding sites), and adult mosquito control (using insecticides). However, residents can play a crucial role in reducing mosquito breeding grounds around their homes.

  • Eliminate Standing Water: Regularly empty and scrub containers that hold water, such as flower pots, bird baths, pet bowls, and gutters.
  • Inspect Your Yard: Look for and eliminate any sources of standing water, even small amounts.
  • Maintain Pools and Spas: Ensure that pools and spas are properly maintained and chlorinated.
  • Protect Yourself: When outdoors, wear long sleeves and pants, and use insect repellent containing DEET, picaridin, or oil of lemon eucalyptus.

Looking Ahead: Surveillance and Response

Vector control districts are continuing to monitor mosquito populations and disease activity closely. Surveillance efforts involve trapping mosquitoes and testing them for viruses. If a mosquito tests positive for a virus, control measures will be implemented to reduce the risk of transmission. The Sutter-Yuba MVCD, for example, is using specialized traps to define the scope of Aedes infestations in their region.

Public health officials emphasize the importance of reporting mosquito bites and any suspected cases of mosquito-borne illness to your local vector control district. Staying informed about mosquito activity in your area and taking preventative measures are the best ways to protect yourself and your community.