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Pests and pest control in Riverside, CA

Pests to know in Riverside

Why each one matters here is cited in the sections below.

Termites in Riverside

Drywood termites are most prevalent in southern California and nest above ground in dry wood without soil contact.[9]

Invasive species reported here

  • The district releases sterile male Aedes aegypti, sterilized with X-rays, to reduce invasive mosquito populations; male mosquitoes do not bite.[4]
  • The brown widow spider became established in Southern California around 2000 and continues to spread, according to UC Riverside's Center for Invasive Species Research.[7]
  • The Asian citrus psyllid, which can spread a deadly citrus disease, was first detected in backyard citrus in Southern California in August 2008.[8]

Pests local experts flag

  • Africanized honeybees colonized Riverside County in 1998 and have essentially displaced feral European honeybees there, becoming the dominant wild bee.[3]
  • The western black-legged tick (Ixodes pacificus) is the tick species of concern in northwest Riverside County.[5]
  • The district says roof rats can enter homes through openings less than one inch wide and advises checking attic vents and roof gaps at least once a year.[6]

Climate

Central Riverside (ZIP 92501) is in USDA plant hardiness zone 10a, where the average coldest winter night is 30 to 35°F.[12]

Public agencies that handle pests

  • The Northwest Mosquito and Vector Control District, headquartered in Corona, serves northwest Riverside County. It was formed on December 28, 1959, to control mosquitoes.[1]
  • The district covers about 350 square miles with roughly 850,000 residents, controlling mosquitoes, flies, rats, Africanized honeybees, black flies and midges.[1]
  • West Nile virus is the mosquito-borne virus of concern for residents of northwest Riverside County, according to the local vector district.[2]

Hiring a licensed company

The state pesticide regulatory agency for California is the California Environmental Protection Agency (Department of Pesticide Regulation), which oversees pesticide applicator certification and licensing.[13]

Licensing agency: California Environmental Protection Agency — Department of Pesticide Regulation[13].

See also how to check a pest control license.

Free local help

The red imported fire ant gained a foothold in Southern California in 1998; UC IPM advises reporting suspected infestations to the county agricultural commissioner.[11]

Through the year

Summer to Fall
In California, drywood termite swarmers usually fly during daytime hours in summer and fall.[10]

Sources

  1. Northwest Mosquito and Vector Control District, “About Us.” www.northwestmvcd.org/about-us (accessed 2026-10-06)
  2. Northwest Mosquito and Vector Control District, “FAQs.” www.northwestmvcd.org/faqs (accessed 2026-10-06)
  3. Northwest Mosquito and Vector Control District, “Bees.” www.northwestmvcd.org/bees (accessed 2026-10-06)
  4. Northwest Mosquito and Vector Control District, “Sterile Insect Technique.” www.northwestmvcd.org/sterile-insect-technique (accessed 2026-10-06)
  5. Northwest Mosquito and Vector Control District, “Ticks.” www.northwestmvcd.org/ticks (accessed 2026-10-06)
  6. Northwest Mosquito and Vector Control District, “Rodents.” www.northwestmvcd.org/rodents (accessed 2026-10-06)
  7. Center for Invasive Species Research, UC Riverside, “Brown Widow Spider.” cisr.ucr.edu/invasive-species/brown-widow-spider (accessed 2026-10-06)
  8. Center for Invasive Species Research, UC Riverside, “Asian Citrus Psyllid.” cisr.ucr.edu/invasive-species/asian-citrus-psyllid (accessed 2026-10-06)
  9. UC Statewide IPM Program (UC Agriculture and Natural Resources), “Subterranean and Other Termites.” ipm.ucanr.edu/home-and-landscape/subterranean-and-other-termites/ (accessed 2026-10-06)
  10. UC Statewide IPM Program (UC Agriculture and Natural Resources), “Drywood Termites.” ipm.ucanr.edu/home-and-landscape/drywood-termites/ (accessed 2026-10-06)
  11. UC Statewide IPM Program (UC Agriculture and Natural Resources), “Ants.” ipm.ucanr.edu/home-and-landscape/ants/ (accessed 2026-10-06)
  12. USDA ARS and PRISM, via phzmapi.org, “Plant hardiness zone for ZIP 92501 (2023 USDA map data).” phzmapi.org/92501.json (accessed 2026-10-06)
  13. National Pesticide Information Center, “State Pesticide Regulatory Agencies.” npic.orst.edu/reg/state_agencies.html (accessed 2026-10-06)

Updated 2026-10-15. Every statement on this page comes from the cited local, state or university source. Spot an error? Tell us.