Snakes and spiders in Marin County, California
Marin County, home of San Rafael, has 10 snake and 37 spider species on record, from 1,246 licensed snake and 536 spider records. Venomous species here: the western rattlesnake and the western black widow.
Are there venomous snakes or spiders in Marin County?
Yes. The western rattlesnake: 51 licensed records, 1% of all California records of it. The western black widow: 20 licensed records, 2% of all California records of it.
What snakes are in Marin County?
In all, 10 snake species are on the Marin County list. The most recorded are the western terrestrial garter snake (382), the aquatic garter snake (347) and the gopher snake (148).
| # | Species | Records | Share of California records |
|---|---|---|---|
| 1 | Western terrestrial garter snake Thamnophis elegans | 382 | 2% |
| 2 | Aquatic garter snake Thamnophis atratus | 347 | 9% |
| 3 | Gopher snake Pituophis catenifer | 148 | 2% |
| 4 | Common garter snake Thamnophis sirtalis | 104 | 2% |
| 5 | Ring-necked snake Diadophis punctatus | 68 | 4% |
| 6 | Western rattlesnake venomous Crotalus oreganus | 51 | 1% |
| 7 | Eastern racer Coluber constrictor | 47 | 4% |
| 8 | California kingsnake Lampropeltis californiae | 32 | 1% |
| 9 | Sharp-tailed snake Contia tenuis | 31 | 3% |
| 10 | Northern rubber boa Charina bottae | 25 | 4% |
When are snakes out in Marin County?
Observation records of snakes in Marin County run mostly February through September, peaking in May with 18% of them, the same peak as California as a whole.
What spiders are in Marin County?
In all, 37 spider species are on the Marin County list. The most recorded are the Johnson jumper (63), the garden spider (29) and the western lynx spider (29).
| # | Species | Records | Share of California records |
|---|---|---|---|
| 1 | Johnson jumper Phidippus johnsoni | 63 | 7% |
| 2 | Garden spider Araneus diadematus | 29 | 6% |
| 3 | Western lynx spider Oxyopes scalaris | 29 | 3% |
| 4 | California turret spider Atypoides riversi | 27 | 7% |
| 5 | Koch's wolf spider Alopecosa kochi | 26 | 3% |
| 6 | Steatoda nobilis | 25 | 1% |
| 7 | Western black widow venomous Latrodectus hesperus | 20 | 2% |
| 8 | Goldenrod crab spider Misumena vatia | 19 | 8% |
| 9 | Banded garden spider Argiope trifasciata | 15 | 5% |
| 10 | Zebra spider Salticus scenicus | 15 | 5% |
| 11 | Black-and-yellow argiope Argiope aurantia | 13 | 9% |
| 12 | California funnel-web spider Calisoga longitarsis | 12 | 7% |
| 13 | Gray house spider Badumna longinqua | 12 | 4% |
| 14 | Cone-shaped orbweaver Cyclosa conica | 10 | 10% |
| 15 | False black widow Steatoda grossa | 10 | 1% |
| 16 | Shamrock orbweaver Araneus trifolium | 10 | 18% |
| 17 | Beach-dwelling jumping spider Terralonus californicus | 9 | 10% |
| 18 | Habronattus tarsalis | 8 | 4% |
| 19 | Zoropsid spider Zoropsis spinimana | 8 | 7% |
| 20 | Habronattus amicus | 7 | 8% |
| 21 | Sixspotted orbweaver Araniella displicata | 7 | 3% |
| 22 | Dysdera crocata | 6 | 1% |
| 23 | Longbodied cellar spider Pholcus phalangioides | 6 | 1% |
| 24 | Mouse spider Scotophaeus blackwalli | 5 | 2% |
| 25 | Buttonhook leafbeetle jumping spider Sassacus vitis | 4 | 0% |
| 26 | Striped lynx spider Oxyopes salticus | 4 | 1% |
| 27 | Colonus hesperus | 3 | 0% |
| 28 | Marbled cellar spider Holocnemus pluchei | 3 | 0% |
| 29 | Zygiella x-notata | 3 | 4% |
| 30 | Mexigonus morosus | 2 | 7% |
| 31 | Northern orb weaver Aculepeira packardi | 2 | 5% |
| 32 | Bold jumper Phidippus audax | 1 | 0% |
| 33 | Diaea livens | 1 | 2% |
| 34 | Gem-shaped orbweaver Araneus gemma | 1 | 1% |
| 35 | Sierra dome spider Neriene litigiosa | 1 | 1% |
| 36 | Cyclosa turbinata | — | — |
| 37 | Nordmann's orbweaver spider Araneus nordmanni | — | — |
When are spiders out in Marin County?
Observation records of spiders in Marin County run through most of the year, peaking in April with 17% of them, the same peak as California as a whole.
What stands out in Marin County
Species for which Marin County holds a large share of all California records: the shamrock orbweaver, 18% (10 of 56).
Common in California, not on the Marin County list
Among the snakes most recorded across California, these do not reach the county list: the western aquatic garter snake (3,716 statewide), the sidewinder (1,923 statewide), the two-striped garter snake (1,620 statewide), the western shovel-nosed snake (1,482 statewide) and the glossy snake (1,425 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), 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 Marin County
Rattlesnakes are on the county list, and so are harmless species often taken for them: 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.
Marin County among California counties
By licensed snake records Marin County ranks 18th 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.