How StateFauna counts snakes and spiders

GBIF, the Global Biodiversity Information Facility, brings together research-grade community observations and museum collections from hundreds of publishers. Two rules decide what those records may do here. Presence: a species is listed for a state from at least 10 records of wild animals under any license, including CC BY-NC, because that a species lives somewhere is a fact, not a work; species known there from 3 to 9 such records are shown apart, as rare. Numbers: every count, share, month and county shown is computed only from records published under CC0 or CC BY 4.0, so a listed species can show few or no counted records, and a count here can be lower than the total GBIF shows for the same species.

A record counts for a state when GBIF places its coordinates inside that state (GADM level-1 code), and for a county by its GADM level-2 code, not by the place name the observer typed. Records without coordinates, marked absent, or flagged with geospatial problems are dropped.

Each specimen counts once. One dataset published in Mexico republishes specimens that U.S. museums publish themselves, so a single specimen would count twice; its 14,531 records inside the 50 states are subtracted from every count. So are 241 records of 28 names that are not living snakes, spiders or scorpions: fossils, and a butterfly that GBIF files under a scorpion genus.

Snakes are the families Colubridae, Natricidae, Dipsadidae, Viperidae, Elapidae, Boidae, Charinidae, Leptotyphlopidae, Typhlopidae and Pythonidae. GBIF has no single node for snakes, so the families are listed one by one. Spiders are the order Araneae and scorpions the order Scorpiones. Subspecies are counted under their species.

Presence rests on records of wild animals: observations and museum specimens. DNA samples, zoo and lab animals and fossils do not make a species part of a state’s fauna; sixty DNA samples of a California scorpion taken in one Kansas county do not put that scorpion in Kansas. A snake or scorpion is also left off a state list when every record comes from a single dataset, no one has reported seeing it there, and no neighboring state lists it: the usual trace of a museum jar filed under the museum’s own location. Spider lists are too sparse next door for that test, so it is not applied to spiders. Left off by this test: Thamnophis ordinoides (GA), Nerodia taxispilota (LA) and Arizona pacata (UT).

GBIF keeps names from before a species was split as separate species. Counted as they come, a museum jar of a Washington rattlesnake filed in 1937 as Crotalus viridis would list the prairie rattlesnake in Washington, where only the western rattlesnake lives, and the same animal would be counted twice. So every GBIF name is read through one taxonomy: SSAR 2017, the standard names list of North American reptiles (Crother, ed., SSAR Herpetological Circular 43), with state ranges from the Reptile Database, for snakes; the World Spider Catalog for spiders and The Scorpion Files for scorpions. The table lists every name rewritten, where, and how many licensed records moved. “Not counted” means the old name in that state can stand for more than one of today’s species, each already listed by its own records, or the record lies outside the species’ known range; such records are added to no species.

Species that were brought in and now live wild are listed and marked introduced in the states named below. The mark covers snakes, scorpions and the medically important spiders; many common house and garden spiders were also introduced long ago and are not marked. A species with no native range in the U.S. is not listed outside these states, and these are never listed: Atractus fuliginosus, Chilabothrus angulifer, Elaphe quadrivirgata, Epicrates cenchria, Eunectes murinus, Python regius and Python sebae.

Datasets that republish other publishers’ specimens are subtracted everywhere: dataset b349f235-926d-43ff-b6f7-fc3c1928f581 (14,531 records subtracted): CONABIO (MX), 'Distribucion potencial de las especies de anfibios y reptiles en categoria de riesgo de Mexico': republishes U.S. museum specimens (SDNHM, MVZ, MSB, LACM, OMNH, UTEP, PSM...) that the museums publish themselves. Confirmed pairs: OMNH 26752 = ad0d4b56 '26752.0'; LACM 135416/135417 = 7a25f7aa (there as Crotalus oreganus, here as C. viridis); secondary_audit 2026-09-29: 25 of 50 sampled institutionCode+catalogNumber found in the museums' own datasets (84b4d6e4 SDNHM 15, 84e823d2 5, ad0d4b56 OMNH 3)..

Under these rules 168 snake, 1611 spider and 78 scorpion species are listed in at least one state, and 239 species have a profile, 239 of them with a photo.

Venomous status follows taxonomy, not descriptions: every pit viper (Viperidae) and coral snake (Elapidae); widow spiders (Latrodectus) and recluse spiders (Loxosceles); among scorpions only the Arizona bark scorpion, Centruroides sculpturatus, including its records filed under the older name C. exilicauda. Every scorpion has venom, and so do almost all spiders, for their prey; the mark means a bite or sting that can need medical care. Some snakes that are not dangerous to people, such as hognose, garter, night and lyre snakes, have enlarged rear teeth and a mild venom for their prey; they are described as mildly venomous but not dangerous. Non-venomous does not mean harmless: large constrictors, the pythons and boas established in Florida, have no venom but can inflict serious bites and constriction injuries, and their pages say so. Harmless lookalikes, the species people often take for venomous ones, follow the usual confusions named in field guides; only their record counts are computed. A lookalike is called the likely identity of a reported venomous animal only where GBIF holds no record of that venomous group in the state under any license. Where a venomous species is recorded in a state fewer times than the list needs, the state page names it with its count; for rattlesnakes, protected in many states, it adds that sensitive species can be withheld from open records. General information, not medical advice. Do not handle or try to identify a snake or spider by this page; if unsure, treat it as venomous.

Seasons come only from observation records (human and machine observations under CC0 or CC BY), not from museum specimens: a collection made at a winter den in one November would otherwise read as a November peak. Months show when records were made, so they mix animal activity with human activity: more people are outdoors in summer. The main season is the shortest run of consecutive months, possibly across the new year, that holds at least 90% of the observation records; where several runs are equally short, the one holding the most records is used. Months outside it together hold under 10% of the records.

A season is given only from 30 observation records with a month. A run of three to nine months is printed as a range, such as March through October; a run of one or two months is called concentrated; a run of ten months or more is not a season, and the animal is described as recorded most of the year. When a species is compared across states by the month its season starts, only seasons that fall within one calendar year are compared. For venomous snakes, a busiest month from November to February outside Florida and Texas is read as a single collection event rather than a season, and no season is given. Quiet months hold under 2% of records.

Absence: a species with no records in a state may still live there, and a single record can be a stray or a released pet. Appearance: records carry no color or size, so this site does not sort species by looks. Abundance: more records mean more people looked, not necessarily more animals; counties near cities and universities are recorded more often.

Photos come from Wikimedia Commons (through each species' Wikidata entry, GBIF taxon ID, property P846), from photos attached to GBIF records and from iNaturalist, and are used only under public domain, CC0, CC BY or CC BY-SA. The license of each photo is checked, not the license of the record it came with. Author and license of every photo are on the photo credits page and under the photo on each species page. Maps, diagrams, figures and plates from papers are not used as photos, nor is a file that Wikimedia Commons files under another species; venomous species are never shown by a drawing or a black-and-white picture. A drawing of a harmless species is used only where no photo exists anywhere, and is labeled Illustration. Where no free photo of a species exists, its card shows a photo of another species of the same genus, or of the genus itself, or, failing that, of a species of the same family, and the card says which.

StateFauna (BiLingoPlus LLC). Snakes and spiders by U.S. state, snapshot 2026-09-29. https://statefauna.com/methodology/

Underlying data: GBIF.org (2026-09-29) GBIF Occurrence Search: species presence from records under any license, numbers from CC0 1.0 and CC BY 4.0 records only; datasets and record counts in https://statefauna.com/data/statefauna-gbif-2026-09-29.csv, https://www.gbif.org/occurrence/search.

The derived dataset behind these pages, read 2026-09-29, lists 2,519,649 records from 276 GBIF datasets: every record used to list a species or to count one, of which 619,071 CC0 or CC BY records are counted in the numbers. Datasets and record counts (CSV).