Venomous snakes and spiders in Wyoming

Wyoming's venomous snakes are two rattlesnake species. Together they account for 275 licensed records; the prairie rattlesnake alone has 92% of them, and the least recorded, the western rattlesnake, has 21.

One widow species (Western black widow: 4 records) is on the Wyoming list. There is no recluse spider on the Wyoming list: no recluse species reaches 10 records in the state. Widow bites cause muscle pain and cramps; recluse bites can cause a slow-healing wound. Both are rare and seldom fatal.

Yes. One scorpion species is recorded in Wyoming, from 7 licensed records: Northern scorpion (5 records). Every scorpion has venom; only the Arizona bark scorpion's sting is medically significant, and it is not on the Wyoming list.

These eight account for 72% of all licensed snake records in Wyoming; the most recorded, the western terrestrial garter snake, alone for 48%.

These eight account for 54% of all licensed spider records in Wyoming; the most recorded, the Groenland wolf spider, alone for 28%.

Observation records of snakes in Wyoming run mostly May through September, peaking in July with 27% of them. December through February together hold under 2% of the records, so snakes in Wyoming are rarely recorded in winter. Venomous snakes alone have 28 observation records with a month in Wyoming, too few for a season of their own.

Observation records of spiders in Wyoming run mostly May through October, peaking in June with 28% of them. Winter (December to February) holds 2% of the records.

Campbell County has the most records of venomous snakes in Wyoming, 154, most of them of the prairie rattlesnake. Sweetwater County and Fremont County follow.

Carbon County leads with 248 records (23%), followed by Campbell County and Teton County; the top five counties hold 61% of the total. 23 of Wyoming's 23 counties have at least one licensed snake record.

Yes. Wyoming has two venomous snake species on its list, the kind people usually call poisonous: prairie rattlesnake and western rattlesnake. Strictly, snakes are venomous (they inject venom), not poisonous (harmful to eat or touch).

Yes. Two species are on the Wyoming list: the prairie rattlesnake and the western rattlesnake, with 275 licensed records between them. Most licensed records of the prairie rattlesnake come from Campbell County, Sweetwater County and Fremont County.

No. GBIF holds no copperhead record for Wyoming under any license.

No. GBIF holds no cottonmouth record for Wyoming under any license.

No. GBIF holds no coral snake record for Wyoming under any license.

Wyoming has 254 licensed records of the prairie rattlesnake, which ranks the state 8th of the 14 states where it reaches our threshold. Most of its licensed records in Wyoming come from Campbell County, Sweetwater County and Fremont County. Range in other states and photos: Prairie rattlesnake profile.

Wyoming has 21 licensed records of the western rattlesnake, which ranks the state 9th of the 9 states where it reaches our threshold. Range in other states and photos: Western rattlesnake profile.

Many snakes and spiders taken for venomous ones are harmless species with a similar look. These are the usual confusions, with each species' licensed records in Wyoming.

No copperheads reach the Wyoming list, and GBIF holds no copperhead record for Wyoming under any license, so a snake taken for one here is most likely a harmless lookalike. Those recorded in the state: central plains milksnake (5).

Rattlesnakes: 275 licensed records in Wyoming. Harmless species often taken for them are also on the state list: gopher snake (112) and plains hog-nosed snake (14). Together they have 126 licensed records, and here the venomous species are the more recorded side, 2.2 to 1.

No coral snakes reach the Wyoming list, and GBIF holds no coral snake record for Wyoming under any license, so a snake taken for one here is most likely a harmless lookalike. Those recorded in the state: central plains milksnake (5).

Recluse spiders are not on the Wyoming list, but they are recorded in Wyoming once (records of any license: brown recluse 1): treat any spider like this as venomous until identified. Harmless species often taken for them in the state: hobo spider (2).

By count of venomous snake species, Wyoming ranks 29th of 50 states, level with 7 other states. Nationally, Arizona leads with 14 species; five list none.

Of the six states bordering Wyoming, Utah, Nebraska and Colorado list more venomous snake species; Idaho lists as many (Wyoming: 2 species; Utah 5, Nebraska 4, Colorado 3, Idaho 2, Montana 1, South Dakota 1).

Venomous snakes listed next door but not in Wyoming: the western massasauga (Colorado and Nebraska); the eastern copperhead (Nebraska); the Mohave rattlesnake (Utah); the sidewinder (Utah); the southwestern speckled rattlesnake (Utah); the timber rattlesnake (Nebraska). The most widely shared is the prairie rattlesnake, listed in all six bordering states.

Yes. One widow species is on the Wyoming list: the western black widow (4 records).

Not on our list: GBIF holds 1 brown recluse record of any license in Wyoming (brown recluse 1), fewer than 10 of any one species; such records can be genuine rarities, strays, transported animals or misidentifications. Treat any spider that looks like a recluse as venomous.

Wyoming has 4 licensed records of the western black widow, which ranks the state 16th of the 18 states where it reaches our threshold. Range in other states and photos: Western black widow profile.