California’s mild climate and ecological diversity make it a great place to live — for people and pests alike. Bay Area homeowners deal with a wider variety of pest species than most regions in the country. This guide covers the ones we see most often and what you can do about each.
Argentine Ants
The Argentine ant (Linepithema humile) is an invasive species that has become one of the most dominant ant species in California. They form massive supercolonies with multiple queens and can number in the billions across a connected territory. They invade homes in large numbers seeking food and moisture. Professional baiting is the most effective control approach.
Western Subterranean Termites
The most destructive structural pest in California. They live underground in large colonies and build mud tubes to access above-ground wood. Annual or biennial termite inspections are strongly recommended for Bay Area homeowners.
Roof Rats
Roof rats are a significant problem in Bay Area neighborhoods with mature trees, ivy, and dense vegetation. They’re excellent climbers and commonly nest in attics, trees, and wall voids. Exclusion and trapping are the primary control tools.
German Cockroaches
The most common indoor cockroach species. German cockroaches reproduce extremely rapidly and are resistant to many pesticides. Professional gel baiting combined with sanitation improvements is the most effective treatment.
Gophers
Pocket gophers are a constant challenge for Bay Area homeowners with yards, gardens, and landscaping. They feed on roots from below and can destroy plantings quickly. Professional trapping is the most reliable control method.
Western Black Widows
Present throughout California, black widows are found in garages, woodpiles, crawlspaces, and other undisturbed areas. The adult female is the only one considered medically significant. Habitat reduction — reducing clutter and debris — is the most effective preventive measure.