Pest and vector control in Palo Alto

Palo Alto's mild climate suits people and pests alike. Roof rats travel along fences, ivy and utility lines. Mosquitoes breed in anything that holds water for a week. Yellowjackets build nests in the ground by late summer. Raccoons, skunks and opossums live in every neighborhood, not just near the creeks and the Baylands.

Help comes from two public agencies with different jobs. The Santa Clara County Vector Control District deals with disease-carrying pests such as mosquitoes and rodents. The City of Palo Alto's Animal Control deals with animals, including sick or aggressive wildlife. Some problems belong to neither and need a private company. This page explains who to call, based on each agency's pages as of November 2026. For dogs, cats and lost pets, see our animal shelter guide.

The Vector Control District

The Santa Clara County Vector Control District was formed in 1988 and covers the whole county, Palo Alto included. It is paid for by a countywide property benefit assessment, with the county Board of Supervisors acting as its trustee. Its stated mission is to detect and minimize vector-borne diseases, abate mosquitoes and help the public with rodent problems.

According to its about page, the district:

• Monitors and tests for diseases carried by animals and insects, such as West Nile virus, plague, rabies and Lyme disease
• Inspects known mosquito and rodent sources and treats breeding sites when needed
• Responds to public service requests about mosquitoes, rodents, wildlife and other pests including ticks, yellowjackets and cockroaches
• Identifies insects and other arthropods through its vector ecologist
• Gives talks to schools, homeowners associations, businesses and civic groups

Service requests go through the district's website or by phone at (408) 918-4770. The city's Animal Control page lists a different number for the district, (800) 675-1155, weekdays only. Either should reach the office; the 408 number is the one on the district's own pages.

What the district does for residents

Rats and mice

Roof rats are common in Palo Alto. They climb well, nest in attics and dense vines and feed on fruit, pet food, birdseed and chicken feed. The district's rodent page offers a free inspection and lists the main fixes:

• Manage vegetation near buildings, especially Algerian ivy, which shelters rats.
• Pick up fallen fruit from fruit trees.
• Check crawlspace vents for missing screens and seal holes larger than a quarter.
• Seal gaps rats could reach from the ground or by climbing walls or using cables from utility poles.

Add a few of your own: trim tree branches back from the roof, store pet food and birdseed in metal bins and bring pet bowls in at night. Backyard chickens bring rats unless feed is locked away, as our backyard chickens guide explains.

About rat poison

Snap traps in enclosed stations are the safest option for most homes. Poisoned rats are eaten by owls, hawks, foxes and pets. California has sharply restricted the most dangerous anticoagulant rodenticides in recent years. If you hire a pest company, ask what it plans to use and where. Unused poisons go to household hazardous waste, not the trash; see our household hazardous waste guide.

Mosquitoes

The district's mosquito page asks residents to report mosquito activity and abandoned or neglected pools. It offers free mosquitofish for pools, ponds, fountains and rain barrels. The fish eat larvae and are meant for contained water only, never creeks or the Bay.

Day-biting mosquitoes deserve a call. Invasive Aedes mosquitoes bite during the day and can carry diseases that local species do not. The district asks residents who notice day biters to phone (408) 918-4770 and to use long sleeves and EPA-registered repellent outdoors.

West Nile virus is the main mosquito-borne disease in the county. Most infected people have no symptoms; older adults and people with weakened immune systems face the highest risk of serious illness. Dead birds, especially crows and jays, are an early warning sign, so report fresh ones to the district.

Cut breeding at home

1. Tip out saucers, buckets, toys and tarps after rain and irrigation.
2. Change birdbath water at least weekly.
3. Keep pool water circulating and above the pump intake, as the district advises.
4. Screen rain barrels; see our rain barrels and graywater guide.
5. Clean gutters so water does not pool.

Yellowjackets, wasps and bees

The district's stinging insects page says it removes yellowjacket and wasp nests in public areas only. On private property, hire a pest control company. Ground nests are common along lawns and paths in late summer and fall. Colonies grow largest just before they die back in winter.

Honey bees are not pests in the same sense. The district refers swarms to the Santa Clara Valley Beekeepers Guild and the city's Animal Control handles bees on public property only. Our beekeeping guide explains how swarm referrals work.

Raccoons, skunks, opossums and coyotes

The city's Animal Control page is clear: no traps or relocation services are available from Animal Control for raccoons, opossums, skunks or squirrels. It refers residents to Santa Clara County Vector Control or a private pest control company. Coyotes are not trapped either. Report aggressive, sick or injured coyotes to the 24-hour dispatch line at (650) 329-2413.

Animal Control officers remove dead wild or stray animals as time permits, but they do not go under houses, decks or roofs. A dead deer on private property goes to a contracted removal service at the owner's cost; the city lists 408-438-0383.

The best defense is exclusion. Close openings under decks and sheds with buried hardware cloth once you are sure no animals are inside, cap chimneys, secure garbage carts and feed pets indoors. Feeding wildlife in city parks is banned and feeding them at home invites more.

Quick guide: who to call

• Rats, mosquitoes, neglected pools, dead birds: Vector Control District, (408) 918-4770.
• Sick, injured or aggressive wildlife, stray animals: Palo Alto Animal Control, (650) 329-2413.
• Raccoons or skunks living under the house, wasp nests at home, termites, ants: a licensed private pest control company.
• Bee swarm on private property: a beekeeper through the local guild.
• Overgrown or trash-filled property attracting pests: report it to the city through Palo Alto 311.

Buying a house? Termites and wood-destroying pests are covered by a separate inspection, explained in our home inspections guide.

Frequently asked questions