Snakes and spiders in Larimer County, Colorado
Larimer County, home of Fort Collins, has 8 snake and 66 spider species on record, from 278 licensed snake and 471 spider records. Venomous species here: the prairie rattlesnake and the western black widow.
Are there venomous snakes or spiders in Larimer County?
Yes. The prairie rattlesnake: 41 licensed records, 3% of all Colorado records of it. The western black widow: 11 licensed records, 7% of all Colorado records of it.
What snakes are in Larimer County?
In all, 8 snake species are on the Larimer County list. The most recorded are the western terrestrial garter snake (90), the gopher snake (56) and the plains garter snake (43).
| # | Species | Records | Share of Colorado records |
|---|---|---|---|
| 1 | Western terrestrial garter snake Thamnophis elegans | 90 | 11% |
| 2 | Gopher snake Pituophis catenifer | 56 | 15% |
| 3 | Plains garter snake Thamnophis radix | 43 | 16% |
| 4 | Prairie rattlesnake venomous Crotalus viridis | 41 | 3% |
| 5 | Eastern racer Coluber constrictor | 26 | 21% |
| 6 | Common garter snake Thamnophis sirtalis | 15 | 14% |
| 7 | Northern water snake Nerodia sipedon | 3 | 7% |
| 8 | Central plains milksnake Lampropeltis gentilis | 2 | 7% |
When are snakes out in Larimer County?
Observation records of snakes in Larimer County run mostly May through October, peaking in May with 23% of them, the same peak as Colorado as a whole.
What spiders are in Larimer County?
In all, 66 spider species are on the Larimer County list. The most recorded are the bold jumper (100), the Apache jumping spider (54) and Habronattus cuspidatus (33). Larimer County holds more than half of all Colorado records of the wetland giant wolf spider, the stone spider and the turf running spider.
| # | Species | Records | Share of Colorado records |
|---|---|---|---|
| 1 | Bold jumper Phidippus audax | 100 | 15% |
| 2 | Apache jumping spider Phidippus apacheanus | 54 | 31% |
| 3 | Habronattus cuspidatus | 33 | 31% |
| 4 | Habronattus altanus | 19 | 38% |
| 5 | Asian wall jumper Attulus fasciger | 18 | 7% |
| 6 | Dysdera crocata | 18 | 16% |
| 7 | Zebra spider Salticus scenicus | 15 | 4% |
| 8 | Western black widow venomous Latrodectus hesperus | 11 | 7% |
| 9 | Goldenrod crab spider Misumena vatia | 10 | 18% |
| 10 | Triangulate bud spider Steatoda triangulosa | 10 | 20% |
| 11 | Barn funnel weaver Tegenaria domestica | 9 | 14% |
| 12 | Peppered jumper Pelegrina galathea | 8 | 22% |
| 13 | Carolina wolf spider Hogna carolinensis | 7 | 33% |
| 14 | Dock spider Dolomedes scriptus | 7 | 47% |
| 15 | California flattened jumping spider Platycryptus californicus | 6 | 21% |
| 16 | Minute jumping spider Talavera minuta | 6 | 21% |
| 17 | Banded garden spider Argiope trifasciata | 5 | 11% |
| 18 | Brilliant jumping spider Phidippus clarus | 5 | 26% |
| 19 | Cat-faced spider Araneus gemmoides | 5 | 18% |
| 20 | Pelegrina aeneola | 4 | 5% |
| 21 | Spotted orbweaver Neoscona crucifera | 4 | 25% |
| 22 | Proszynski's jumping spider Evarcha proszynskii | 3 | 23% |
| 23 | Western lynx spider Oxyopes scalaris | 3 | 27% |
| 24 | Wetland giant wolf spider Tigrosa helluo | 3 | 50% |
| 25 | Arabesque orbweaver Neoscona arabesca | 2 | 29% |
| 26 | Groenland wolf spider Pardosa groenlandica | 2 | 4% |
| 27 | Hobo spider Eratigena agrestis | 2 | 7% |
| 28 | Longbodied cellar spider Pholcus phalangioides | 2 | 40% |
| 29 | Parson spider Herpyllus ecclesiasticus | 2 | 12% |
| 30 | Pelegrina furcata | 2 | 18% |
| 31 | Sixspotted orbweaver Araniella displicata | 2 | 6% |
| 32 | Stone spider Pardosa lapidicina | 2 | 100% |
| 33 | Turf running spider Philodromus cespitum | 2 | 67% |
| 34 | Bronze jumper Eris militaris | 1 | 17% |
| 35 | Buttonhook leafbeetle jumping spider Sassacus vitis | 1 | 8% |
| 36 | Common candy-striped spider Enoplognatha ovata | 1 | 4% |
| 37 | Dictyna bellans | 1 | 33% |
| 38 | Forest wolf spider Hogna frondicola | 1 | 12% |
| 39 | McCook's split wolf spider Schizocosa mccooki | 1 | 5% |
| 40 | Oblong running spider Tibellus oblongus | 1 | 33% |
| 41 | Ornamental orbweaver Larinioides patagiatus | 1 | 14% |
| 42 | Pardosa sternalis | 1 | 8% |
| 43 | Pelegrina arizonensis | 1 | 17% |
| 44 | Tigrosa grandis | 1 | 17% |
| 45 | Agelenopsis oklahoma | — | — |
| 46 | Blazed dwarf weaver Erigone blaesa | — | — |
| 47 | Celer crab spider Mecaphesa celer | — | — |
| 48 | Dictyna calcarata | — | — |
| 49 | Dictyna coloradensis | — | — |
| 50 | Johnson jumper Phidippus johnsoni | — | — |
| 51 | Long-jawed orb weaver Tetragnatha laboriosa | — | — |
| 52 | Multicolored bark crab spider Bassaniana versicolor | — | — |
| 53 | Nearctic white-striped running crab spider Philodromus rufus | — | — |
| 54 | Northern yellow sac spider Cheiracanthium mildei | — | — |
| 55 | Pale thin-legged wolf spider Pardosa distincta | — | — |
| 56 | Pardosa steva | — | — |
| 57 | Pennsylvania grass spider Agelenopsis pennsylvanica | — | — |
| 58 | Psilochorus imitatus | — | — |
| 59 | Riparian sac spider Clubiona riparia | — | — |
| 60 | Steatoda grandis | — | — |
When are spiders out in Larimer County?
Observation records of spiders in Larimer County run mostly April through October, peaking in June with 19% of them; across Colorado the peak is August.
What stands out in Larimer County
Species for which Larimer County holds a large share of all Colorado records: Habronattus altanus, 38% (19 of 50); the Apache jumping spider, 31% (54 of 176); Habronattus cuspidatus, 31% (33 of 108); the eastern racer, 21% (26 of 123); the triangulate bud spider, 20% (10 of 49); the goldenrod crab spider, 18% (10 of 57); the plains garter snake, 16% (43 of 262); Dysdera crocata, 16% (18 of 111).
Common in Colorado, not on the Larimer County list
Among the snakes most recorded across Colorado, these do not reach the county list: the coachwhip (58 statewide), the western rattlesnake (47 statewide), the plains hog-nosed snake (45 statewide), the western ground snake (36 statewide) and the glossy snake (33 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 Colorado, these do not reach the county list: the Texas brown tarantula (71 statewide). Few records here can mean the species is rare in the county, or that few people have looked.
Harmless lookalikes in Larimer County
No copperheads reach the county list, and GBIF holds no copperhead record for Colorado under any license, so one reported here is most likely a harmless lookalike: the northern water snake and the central plains milksnake. No cottonmouths reach the county list, and GBIF holds no cottonmouth record for Colorado under any license, so one reported here is most likely a harmless lookalike: the northern water snake. Rattlesnakes are on the county list, and so are harmless species often taken for them: the gopher snake. No coral snakes reach the county list, and GBIF holds no coral snake record for Colorado under any license, so one reported here is most likely a harmless lookalike: the central plains milksnake. Widow spiders are on the county list, and so are harmless species often taken for them: the triangulate bud spider. Recluse spiders are not on the Colorado list, but GBIF holds 20 recluse spider records of any license in Colorado (brown recluse 18, Apache recluse 2), 1 of them in Larimer County: treat any spider like this as venomous until identified. Harmless species often taken for them here: the hobo spider, the longbodied cellar spider and the Pennsylvania grass spider.
Larimer County among Colorado counties
By licensed snake records Larimer County ranks 3rd of 63 Colorado counties with any.
Other Colorado counties with their own page: Weld County, Boulder County and El Paso County.
The whole state: venomous species in Colorado, all snakes, all spiders.
GBIF records read 2026-09-29. Listed: any license. Counted: CC0/CC BY only. How we count.