Skip to main content

State Association Press Release: Record Amounts of Rain Coupled With Warming Temperatures Create Perfect Conditions for Mosquitoes

May contain: logo, trademark, and symbol

Published by: Mosquito and Vector Control Association of California


SACRAMENTO – April 17, 2019 – After the significant rainfall we received this winter, mosquito experts throughout the state stress the need for Californians to dump and drain all standing water. According to the California Department of Water Resources, parts of Los Angeles, Ventura and San Diego counties received nearly 200% of the average rainfall from October 2018 to February 2019. These and other areas of the state have accumulated significant amounts of stagnant water, which can create mosquito breeding sites.

Mosquito awareness week

In addition to being a nuisance, mosquitoes pose a serious public health risk as infected mosquitoes can spread West Nile virus, which can cause debilitating cases of meningitis, encephalitis, and even death. West Nile virus activity was detected in 41 counties in California in 2018 and there were 217 human disease cases reported, of which 153 were the more severe neuroinvasive form. Over the last 10 years, more than 4,000 human disease cases were reported including 211 deaths.

“Warm weather coupled with large amounts of stagnant water from recent rain events create the perfect conditions for mosquito breeding,” said Jeremy Wittie, president of the Mosquito and Vector Control Association of California (MVCAC). “Mosquitoes can lay their eggs in sources of water as small as a bottle cap and can complete their life cycle, from egg to adult, in about a week. California residents must do their part to help protect public health by dumping and draining all standing water to eliminate mosquitoes from their communities.”

Mosquito and vector control agencies throughout the state have received an increase in public service requests regarding aggressive day-biting mosquitoes. These signs point to an early and active mosquito season. To raise awareness and educate Californians about the public health threat mosquitoes pose to our communities, the California Legislature declared April 21-27, 2019 as Mosquito Awareness Week.

“Many of us, including myself, have lost dear friends and loved ones to mosquito-transmitted diseases like West Nile virus infection. The risks are all too real, and awareness is one critical tool we can use to save lives,” said Senator Henry Stern. “All Californians play an important role in protecting public health and should take simple measures to reduce the risk of mosquito-transmitted diseases in their community.”

California is also home to invasive Aedes mosquitoes, which are vectors of Zika, dengue, chikungunya and yellow fever viruses. These mosquitoes continue to spread and are now established in 12 counties in the Central Valley and Southern California. With thousands of international travelers arriving or returning to California each year from areas where these viruses regularly occur, the potential for local transmission of imported diseases in the state is increasing. The arrival of a single traveler with an active infection into an area with invasive mosquitoes opens the door for these diseases to spread.

To minimize exposure to mosquito bites:

  • Apply insect repellent containing EPA-registered active ingredients, including DEET, picaridin, oil of lemon eucalyptus, or IR3535, according to label instructions. Repellents keep mosquitoes from biting. DEET can be used safely on infants and children 2 months of age and older.
  • Dress in loose-fitting long sleeves and pants.
  • Install screens on windows and doors and keep them in good repair.
  • Eliminate all sources of standing water on your property, including in flower pots, old tires, buckets, pet dishes and trash cans.
  • Repair leaking faucets and broken sprinklers.
  • Clean rain gutters clogged with leaves.
  • Report neglected swimming pools and day-biting mosquitoes to your local mosquito and vector control agency.

For additional information on mosquitoes and mosquito-borne diseases please visit the California Department of Public Health. Travelers should refer to the CDC’s Travel Advisories.