Vinegaroons: The Harmless Whip Scorpion That Sprays Acid

Vinegaroons look like a horror-film cross between a scorpion and a spider, which is why they cause so much alarm when one walks across a patio after a summer storm. University of Florida entomologists describe a first encounter as alarming but the animal as “fairly benign”. This guide covers what it is, what a pinch or a spray actually does, where the US species live, and when they come out, with our own analysis of iNaturalist records.

Vinegaroon, scorpion or camel spider?

The tail settles it. A scorpion’s tail is segmented and ends in a stinger. A vinegaroon’s is a fine, flexible thread, and University of Florida extension notes it works as a sensory organ, not a weapon. If you are unsure which scorpion you have, our bark scorpion guide covers the species that does sting, and our camel spider guide covers the fast, tailless desert arachnid that is often mixed up with both.

What is a vinegaroon?

Vinegaroons are whip scorpions, an order of arachnids separate from both spiders and true scorpions. UF/IFAS (EENY-493) states that while it is called a scorpion, it has neither the venom-filled stinger of a scorpion nor the venomous bite of some spiders. The common names each describe one feature:

• Whip scorpion refers to the long, thin tail, called the caudal flagellum or telson.
• Vinegaroon comes from the vinegar smell of its defensive spray.
• Grampus is an older regional name. UF suggests it may borrow from the mantis shrimp, also called a grampus, which shrimpers know for a fast, cutting pinch.

The body has a pair of heavy, pincer-tipped pedipalps at the front, used to catch and crush prey. Texas A&M notes that the first pair of legs is long and thin and used like antennae, so the animal walks on the other three pairs. It has eight eyes, but UF describes them as weak, and the feeler legs and the whip help make up for poor vision.

Texas Parks and Wildlife adds a piece of local history: the old west Texas town of Vinegaroon, associated with “Judge” Roy Bean, was named for how common the animals were in the surrounding area.

One species became three

Older guides, including the UF fact sheet, describe one US species, Mastigoproctus giganteus, found in Arizona, Florida, New Mexico, Oklahoma and Texas. A 2018 revision by Barrales-Alcalá, Francke and Prendini in the Bulletin of the American Museum of Natural History split it into seven species and stated that three occur in the United States, one each in Arizona, Texas and Florida. The Arizona animal is now M. tohono, the Florida one M. floridanus, which UF says is endemic to the state, and the name M. giganteus stays with the Texas form. For a homeowner nothing changes: all three look alike and behave the same way.

Is a vinegaroon a spider or scorpion?

Neither. It is an arachnid, so it has eight legs and two main body sections like spiders and scorpions, but it belongs to its own order, Uropygi. It lacks the silk and venomous fangs of spiders and the venomous sting of scorpions. The closest everyday comparison is a scorpion that has swapped its stinger for an acid sprayer and a feeler.

How the acid spray works

When threatened, a vinegaroon either retreats into its burrow or rears up and spreads its pedipalps in a bluff display. If that fails, it sprays. UF/IFAS says it can accurately spray acetic acid from a pore at the base of the tail to a distance of a few inches to one foot, and that the spray is not dangerous to skin but stings severely in an animal’s eyes or nostrils.

The chemistry was worked out by Thomas Eisner, Jerrold Meinwald and colleagues in a 1961 study. Meinwald later described the secretion as 85 per cent acetic acid, 10 per cent water and 5 per cent octanoic (caprylic) acid. The small octanoic fraction matters: it lets the acid penetrate insect cuticle, and without it, he wrote, the acetic acid was ineffective at harming cockroaches and fly larvae. Household vinegar, by comparison, is expected to contain about 4 grams of acetic acid per 100 mL under FDA labelling guidance.

What happens if you get bit by a vinegaroon?

Usually a pinch rather than a bite. Vinegaroons have no venom, so there is nothing to inject. Their main weapon against a hand is the pair of pedipalps. UF entomologist William Kern describes it as a mild pinch, like being bitten by a small anole lizard, and says they are considered harmless to people and pets. The UF fact sheet notes that mishandled pedipalps can give a noticeable pinch, and Texas Parks and Wildlife says they will bite if provoked.

The spray is the more likely problem, and it is an irritation rather than an injury. Kern’s advice is to wash skin with soap and water before touching your eyes, and to flush the eyes with clean water if spray gets in them. Anyone with eye pain or irritation that persists after rinsing should get medical advice.

Can a vinegaroon hurt you, or kill you?

It can startle you, pinch you and make your eyes sting. It cannot poison you, and none of the extension sources we read reports serious harm to people. Kern’s summary is blunt: they are neither venomous nor physically hazardous. UF also notes that most mammals and birds avoid eating them because they taste bad, though they are not poisonous.

Where are vinegaroons found in the US?

Texas A&M says the Texas species is found mainly in west Texas, especially the Trans-Pecos, with reports as far north as the Panhandle and in south Texas. UF says the Florida whip scorpion lives in deep, well-drained sandy soils such as longleaf pine sandhills, sand pine scrub and coastal dunes. In the Southwest they are animals of desert and grassland, but UF notes the group also turns up in scrub, pine forest and barrier islands.

Arizona dominates our iNaturalist analysis at 3.43 records per 10,000 observations (736 records), followed by New Mexico at 1.70 (151 records) and Florida at 0.21 (118 records). Texas shows only 2 research-grade records, and that needs explaining, because Texas plainly has vinegaroons. When we checked in October 2026, more than 700 Texas vinegaroon observations on iNaturalist were still marked as needing identification, most of them identified only to genus since the 2018 split, so they drop out of research-grade counts. Read the Texas bar as a gap in identification, not an absence of animals. iNaturalist files New Mexico’s research-grade records under the Arizona species.

When do vinegaroons come out?

Vinegaroon records are almost flat from January to May, then rise in June and explode in July and August, when their share of everything Americans record on iNaturalist runs at about three and a half to four times its yearly average. By October it has fallen back. Most records come from Arizona and New Mexico, so the peak falls in the Southwest’s summer monsoon months. UF describes the same pattern in Florida: vinegaroons spend the driest periods underground and come to the surface during the rainy season, May or June to November.

The comparison with other desert arachnids in the same dataset is striking. Camel spiders peak in May, well before it, and the Arizona bark scorpion is recorded through most of the year. A vinegaroon on the porch is a sign of wet weather, the same trigger that brings in many of the visitors in our guide to bugs in the house after rain.

They are strictly night hunters. UF says they spend the day in burrows they dig with their pedipalps, or under logs, boards, rotting wood and rocks.

What vinegaroons eat

UF lists soft-bodied insects such as termites, cockroaches and crickets as the main prey, and notes that one common prey item of Florida adults is the Florida woods roach. UF/IFAS Extension Sarasota County adds beetles, ants, flies, and occasionally slugs and worms. Prey is crushed between special teeth on the pedipalps. That diet is why Kern’s answer to “how do I get rid of them” is a question: why get rid of them, when they eat cockroaches and millipedes?

They are prey too. UF names raccoons, coatis, armadillos, skunks, bears, feral hogs and peccaries as predators.

A slow life: from egg sac to seven years

Vinegaroons are long-lived for arachnids. UF says they can live at least seven years, growing slowly and taking about three years and three molts to reach adulthood, then living up to four more years.

Mating takes place in autumn and involves a courtship that UF says lasts eight to 12 hours. The female carries the eggs inside her body for several months, then lays 30 to 40 eggs into a fluid-filled sac held under her abdomen and stays in her burrow holding it for about two months. The white young climb onto her back for about a month, leave after their first molt, and the mother dies soon after. The Oregon Zoo gives a slightly wider clutch range of 20 to 40 eggs.

Are vinegaroons good pets?

Extension sources disagree, and the disagreement is useful. UF/IFAS Extension Sarasota County says their longevity and low maintenance make them an interesting pet choice. UF entomologist William Kern takes the opposite view: they rarely do well in captivity, and collection for the pet trade has harmed most populations, especially in Florida, where he says the Florida whip scorpion is declining from habitat loss and over-collecting. Texas Parks and Wildlife also cites habitat loss and the pet trade as reasons numbers are falling. Kern’s own advice is to photograph them in the field and leave them in peace.

Found one at home: what to do

There is no reason to spray a pesticide or call a professional for vinegaroons. If you are also finding scorpions indoors, that is worth acting on, and our guide to common house bugs in Texas sets out which desert visitors matter and which do not.

Frequently asked questions

What happens if you get bit by a vinegaroon?

Usually nothing more than a pinch. Vinegaroons have no venom and no stinger. They grip with their pincer-like pedipalps, which University of Florida entomologist William Kern compares to being bitten by a small anole lizard. The acid spray is more likely to bother you: it stings the eyes and nose. Kern advises washing skin with soap and water and flushing eyes with clean water; persistent eye irritation needs medical advice.

Where are vinegaroons found in the US?

Vinegaroons live in Arizona, New Mexico, Texas and Florida. A 2018 revision recognised three US species, one each in Arizona, Texas and Florida. In Texas they are mainly in the west, especially the Trans-Pecos. In Florida they live in deep, sandy soils such as pine sandhills and scrub. Arizona has by far the most iNaturalist records relative to all observations.

Is a vinegaroon a spider or scorpion?

Neither. A vinegaroon is a whip scorpion, an arachnid in its own order, Uropygi (also called Thelyphonida). It has eight legs like spiders and scorpions, but walks on six and uses its long, thin front legs as feelers. Unlike a scorpion, its tail is a thin sensory whip with no stinger, and unlike many spiders, it has no venomous bite.

Are vinegaroons good pets?

Opinions differ. They can live seven years or more, and UF/IFAS Extension Sarasota County calls them an interesting, low-maintenance pet. UF entomologist William Kern says they rarely do well in captivity and that collecting for the pet trade has hurt wild populations, especially in Florida. Kern recommends enjoying them in the field and leaving wild animals in place.

Why do vinegaroons smell like vinegar?

Their defensive spray is mostly acetic acid, the acid in vinegar. Research by Eisner and Meinwald’s group found it is about 85 per cent acetic acid, 10 per cent water and 5 per cent octanoic acid, far stronger than household vinegar at about 4 per cent. They aim it from glands at the base of the tail, reaching a few inches to a foot.

Sources

• UF/IFAS Extension, EENY-493 (IN890), Giant Whip Scorpion Mastigoproctus giganteus giganteus, W.H. Kern and R.E. Mitchell, 2011, reviewed 2020.
• UF/IFAS News, Come across this giant whip scorpion in your area? UF/IFAS expert explains what to expect, 2021.
• UF/IFAS Extension Sarasota County, The Spooky Bug Brigade: Whip Scorpions, 2024.
• Texas A&M AgriLife Extension, Field Guide to Common Texas Insects: Vinegaroon; Striped Bark Scorpion.
• Barrales-Alcalá, Francke and Prendini, Systematic Revision of the Giant Vinegaroons of the Mastigoproctus giganteus Complex, Bulletin of the American Museum of Natural History 418, 2018.
• Meinwald, J., The Insect as Synthetic Chemist, Engineering and Science (Caltech), May 1986, describing Eisner, Meinwald, Monro and Ghent, Journal of Insect Physiology, 1961.
• US Food and Drug Administration, Compliance Policy Guide Sec. 525.825, Vinegar, Definitions.
• Texas Parks and Wildlife Magazine, Vinegaroons sport a whip-like tail and spray acid.
• Oregon Zoo, Vinegaroon.
• National Park Service, Bark Scorpion; University of Arizona Cooperative Extension, Solpugids.
• The Pest Control Brief analysis of iNaturalist research-grade records, pulled October 2026.