What are the common household pests in San Diego, and what will the County do for free?

San Diego homes mostly battle four pests: roof rats, Argentine ants, invasive Aedes mosquitoes and termites, and the County will help with two of them for free. The County of San Diego Vector Control Program inspects for rats, gives away mosquitofish and responds to mosquito reports at no charge; its FAQ says those services are funded by assessments on your property tax bill, so you've already paid for them. We checked the County's pages and UC Integrated Pest Management (UC IPM) guides on November 3, 2026. For termites, see our separate guide to termite inspections in San Diego. Coyotes are a wildlife question; see coyotes in San Diego neighborhoods.

Does San Diego County get rid of rats for free?

No, but it will inspect your property for free and give you a Rat Control Starter Kit. The County says it is not a pest control company and will not trap, bait or remove rodents, so after the visit you either follow its plan yourself or hire a company. Roof rats, the most common kind here, climb rather than burrow. UC IPM's June 2025 rat guide says they nest in trees, shrubs, attics and wall voids, favor avocados and citrus, and routinely travel 300 feet or more for food.

• —Seal gaps: the County says anything larger than a quarter; UC IPM says over 1/4 inch, and notes young rats fit under a door with a 1/2-inch gap
• —Trim: cut tree limbs back from the roof and thin English ivy, star jasmine and honeysuckle on fences and walls
• —Remove food: pick up fallen fruit, pet food and bird seed; keep woodpiles 18 inches off the ground
• —Trap up high: UC IPM recommends snap traps on ledges, fences and branches, about 10-20 feet apart

Why are mosquitoes biting me during the day in San Diego?

Daytime ankle bites usually mean invasive Aedes mosquitoes, which the County first found here in 2014. They are small and black-and-white striped, bite mostly on the legs and ankles, and are most active in summer and fall. They breed in small containers like flowerpot saucers, and the County says even a quarter inch of water is enough; their eggs survive dry for months, so scrub containers as well as emptying them. Aedes aegypti and Aedes albopictus can spread dengue, Zika and chikungunya; the County notes it recorded its first locally acquired dengue case in 2025, while most local cases come from travelers.

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County office

1. 1County Vector Control Program — Mon-Fri 8 a.m.-noon and 1-4 p.m.; (858) 694-2888
2. 2Lakeside Community Center — Mon-Fri noon-8 p.m.

Central San Diego

1. 3City Farmers Nursery — Tue-Sun 9 a.m.-5 p.m.
2. 4Pet Kingdom — Mon-Sat 10 a.m.-6 p.m., Sun 10 a.m.-5 p.m.
3. 5Walter Andersen Nursery (Point Loma) — Daily 8 a.m.-5 p.m.

North County

1. 6Walter Andersen Nursery (Poway) — Daily 9 a.m.-5 p.m.
2. 7Pet Supplies Plus — Mon-Sat 9 a.m.-8 p.m., Sun 10 a.m.-7 p.m.
3. 8Underwater Environments — Mon-Sat 9 a.m.-5 p.m., Sun 10 a.m.-4 p.m.

Source: County of San Diego Vector Control Program mosquitofish locations list, checked Nov 3, 2026. Call ahead to confirm stock.

See these on the full San Diego map

How do I get rid of Argentine ants in San Diego?

Use baits outdoors, not perimeter sprays. UC IPM calls the Argentine ant the most common ant around California homes; its colonies link into one huge supercolony with many queens, so killing the ants you see doesn't end the problem. Workers carry bait back and share it. UC IPM suggests sweet liquid baits (0.5% to 1% borate in sugar water, in refillable stations) placed every 10 to 20 feet around the foundation; results can take a week or more. Perimeter sprays kill only foragers and can push ants indoors. Ants often move inside during rain or hot, dry spells, so expect a wave with the first winter storms.