Snakes and spiders in San Francisco County, California
San Francisco County, home of San Francisco, has 5 snake and 30 spider species on record, from 391 licensed snake and 641 spider records. Venomous species here: the western black widow.
Are there venomous snakes or spiders in San Francisco County?
Yes. The western black widow: 3 licensed records, 0% of all California records of it.
What snakes are in San Francisco County?
In all, 5 snake species are on the San Francisco County list. The most recorded are the western terrestrial garter snake (297), the aquatic garter snake (31) and the gopher snake (17).
| # | Species | Records | Share of California records |
|---|---|---|---|
| 1 | Western terrestrial garter snake Thamnophis elegans | 297 | 1% |
| 2 | Aquatic garter snake Thamnophis atratus | 31 | 1% |
| 3 | Gopher snake Pituophis catenifer | 17 | 0% |
| 4 | Eastern racer Coluber constrictor | 14 | 1% |
| 5 | Ring-necked snake Diadophis punctatus | 3 | 0% |
When are snakes out in San Francisco County?
Observation records of snakes in San Francisco County run mostly March through September, peaking in April with 36% of them; across California the peak is May.
What spiders are in San Francisco County?
In all, 30 spider species are on the San Francisco County list. The most recorded are the garden spider (108), Steatoda nobilis (62) and the Johnson jumper (47). San Francisco County holds more than half of all California records of Tricholathys monterea and Phanias albeolus.
Same family (Dictynidae): Emblyna sublata
| # | Species | Records | Share of California records |
|---|---|---|---|
| 1 | Garden spider Araneus diadematus | 108 | 24% |
| 2 | Steatoda nobilis | 62 | 3% |
| 3 | Johnson jumper Phidippus johnsoni | 47 | 5% |
| 4 | Gray house spider Badumna longinqua | 33 | 10% |
| 5 | Tricholathys monterea | 33 | 67% |
| 6 | Longbodied cellar spider Pholcus phalangioides | 26 | 4% |
| 7 | Dysdera crocata | 25 | 4% |
| 8 | False black widow Steatoda grossa | 24 | 2% |
| 9 | Shamrock orbweaver Araneus trifolium | 24 | 43% |
| 10 | Zygiella x-notata | 24 | 31% |
| 11 | Mouse spider Scotophaeus blackwalli | 20 | 7% |
| 12 | Goldenrod crab spider Misumena vatia | 19 | 8% |
| 13 | Phanias albeolus | 15 | 56% |
| 14 | Zelotes discens | 15 | 45% |
| 15 | Micaria utahna | 11 | 29% |
| 16 | Zelotes tenuis | 10 | 28% |
| 17 | Pelegrina aeneola | 8 | 8% |
| 18 | Buttonhook leafbeetle jumping spider Sassacus vitis | 6 | 1% |
| 19 | Neriene digna | 5 | 8% |
| 20 | Arabesque orbweaver Neoscona arabesca | 4 | 9% |
| 21 | Koch's wolf spider Alopecosa kochi | 4 | 0% |
| 22 | Bold jumper Phidippus audax | 3 | 0% |
| 23 | Western black widow venomous Latrodectus hesperus | 3 | 0% |
| 24 | Banded garden spider Argiope trifasciata | 2 | 1% |
| 25 | Barn funnel weaver Tegenaria domestica | 2 | 17% |
| 26 | Common candy-striped spider Enoplognatha ovata | 2 | 18% |
| 27 | Heliophanus apiatus | 2 | 4% |
| 28 | Zebra spider Salticus scenicus | 2 | 1% |
| 29 | Zoropsid spider Zoropsis spinimana | 2 | 2% |
| 30 | Flatmesh weaver Oecobius navus | — | — |
When are spiders out in San Francisco County?
Observation records of spiders in San Francisco County run through most of the year, peaking in October with 18% of them; across California the peak is April.
What stands out in San Francisco County
Species for which San Francisco County holds a large share of all California records: Tricholathys monterea, 67% (33 of 49); Phanias albeolus, 56% (15 of 27); Zelotes discens, 45% (15 of 33); the shamrock orbweaver, 43% (24 of 56); Zygiella x-notata, 31% (24 of 78); Micaria utahna, 29% (11 of 38); Zelotes tenuis, 28% (10 of 36); the garden spider, 24% (108 of 457).
Common in California, not on the San Francisco County list
Among the snakes most recorded across California, these do not reach the county list: the common garter snake (5,777 statewide), the western rattlesnake (5,224 statewide), the western aquatic garter snake (3,716 statewide), the California kingsnake (2,675 statewide), the sidewinder (1,923 statewide) and the two-striped garter snake (1,620 statewide). Few records here can mean the species is rare in the county, or that few people have looked.
Among the spiders most recorded across California, these do not reach the county list: the half-edged wall jumping spider (2,178 statewide), the western lynx spider (1,123 statewide), the marbled cellar spider (805 statewide), Habronattus pyrrithrix (800 statewide) and the brown widow (776 statewide). Few records here can mean the species is rare in the county, or that few people have looked.
Harmless lookalikes in San Francisco County
No rattlesnakes reach the county list, but the western rattlesnake, the sidewinder, the red diamond rattlesnake, the Mohave rattlesnake, the southwestern speckled rattlesnake, the Panamint rattlesnake and the western diamondback rattlesnake are on the California list: treat any snake like them as venomous until identified. Harmless species often taken for them here: the gopher snake. Widow spiders are on the county list, and so are harmless species often taken for them: the false black widow. No recluse spiders reach the county list, but the desert recluse is on the California list: treat any spider like it as venomous until identified. Harmless species often taken for them here: the longbodied cellar spider.
San Francisco County among California counties
By licensed snake records San Francisco County ranks 37th of 58 California counties with any.
Other California counties with their own page: San Diego County, Lassen County, Shasta County, Riverside County, San Bernardino County, Humboldt County, Sonoma County and San Mateo County.
The whole state: venomous species in California, all snakes, all spiders.
GBIF records read 2026-09-29. Listed: any license. Counted: CC0/CC BY only. How we count.