Giant Desert Hairy Scorpion – Largest scorpion in North America

We found several bark scorpions in our Arizona yard but this is the first time we found a Giant Desert Hairy ScorpionHadrurus arizonensis.  This giant scorpion is the largest scorpion in the United States.

Scorpions are related to spiders, ticks, mites, etc… They are venomous arthropods in the class Arachnida.   Scorpions have over 1,300 species throughout the world.  They have four pairs of legs and pedipalps with plier-like pincers on the end.

giant desert hairy scorpion
Hadrurus arizonensis, Giant Desert Hairy Scorpion

Three species of scorpions are commonly found in the Arizona Desert:

  1. Small Bark Scorpion, Centruroides exilicauda
  2. Striped Tail or Devil’s Scorpion, Vaejovis spinigerus
  3. Giant Desert Hairy Scorpion, Hadrurus arizonensis

Arizona is home to more than 30 species of scorpions but the only truly “life threatening” one is the small Bark Scorpion.  Unlike the other species, Bark Scorpions like to climb.

Giant Arizona Scorpion
the largest scorpion in the US

Scorpions have mouthparts called chelicerae that enable it to rip and tear its prey while feeding.  They have a sensitive antennae along with the pincer-like pedipalps that are used to hold the prey while inflicting venom or eating.  The Scorpion’s body has two main parts; the cephalothorax and the abdomen.

Hadrurus arizonensis
the largest scorpion in North America, Hadrurus arizonensis

According to the book Scorpions: A Complete Pet Owner’s Manual, in order to measure a scorpion; start from the tip of the telson, stinger, to the prosoma, head.  Our Arizona scorpion was just over 5 inches!  Giant Hairy Scorpions have a dark back.

scorpion tail stinger
Giant Desert Hairy Scorpion Tail, metasoma

The metasoma (tail) of the scorpion is actually an extension of the abdomen. It consists of five segments, each one longer than the last; at the tip is the telson (stinger).

All Scorpions are nocturnal and leave their shelters at night in search for prey.  A Giant Hairy Scorpion burrows deep in the desert soil.  This large scorpion follows the moisture level in the soil and can burrow as far as 8 feet below the surface!

home / nest of the scorpion
Scorpion burrow opening

Scorpion burrows are commonly oval or crescent-shaped.

large Arizona Scorpion
Giant Desert Hairy Scorpion in Arizona

Although this scorpion is very large, the sting is somewhat mild and feels similar to a bee sting.  The sting is not life threatening.  If by some chance you experience an allergic reaction to a Giant Hairy Scorpion sting,  seek medical attention immediately.

Scorpions give birth to live young during the summer months and the babies safely ride on mom until their first molt, approximately 2-3 weeks.

If you really want to observe these ancient nocturnal arachnids, take a black light to the desert on a moonless, warm night.   In the dark you will be able to see scorpions dig burrows, capture prey and possibly witness a unique mating ritual.

How do we try to keep our home scorpion free?  By keeping our windows and doors closed!  When opening a door in the desert, make it a habit to look at the bottom.  It is known that scorpions have poor eyesight and tend to walk along walls.  Glue boards placed by doors and windows are good ways to catch scorpions inside the home.  Bark Scorpions are smaller and more common in homes.  Bark Scorpion stings can be fatal so we have a contract with Truly Nolen that helps to keep our home safe. 

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Arkenstone Cave in AZ – Protected living cave at Colossal Park

Arkenstone Cave was discovered near the Rincon Mountains of Southeastern Arizona in the 1960’s.  This living cave is protected by the county and accessible only to a few scientists and researchers.

wet live cave in Arizona
Arkenstone Cave in Arizona

We have spent a great deal of time investigating information regarding Arkenstone and La Tetera Caves.  Our most important finding has been the fact that Pima County regards these living caves as treasure troves of precious, immeasurable scientific information.

Access is extremely limited; but a visit to Colossal Cave Mountain Park Museum can provide the curious with results of the past and latest research conducted inside Arkenstone Cave.

Here are some of the research highlights provided from the Museum Caving Rooms at Colossal Cave east of Tucson, AZ.

Colossal Cave Mountain Park
Arkenstone Cave is used for research

ARKENSTONE is an active KARST CAVE, which means the breaking down of limestone has produced fissures, sinkholes, caverns and underground streams.

Most caves are formed in limestone.  Simply put, it dissolves from precipitation mixing with carbon dioxide and the decaying organic material in the soil.  This dissolution process is extremely slow.  Thousands upon thousands of years!

Arkenstone karst caves
Karst diagram, Limestone Caves

Karst image courtesy of  www.geocaching.com

Arkenstone, La Tetera and Colossal Caves are located in Colossal Cave Mountain Park, Arizona.  Colossal Cave is dry and considered a dead cave.  La Tetera and Arkenstone are alive and adorned with calcium carbonate formations produced through slow precipitation.

SPELEOTHEMS in Arkenstone Cave
Arkenstone Cave Crystal formations

Mineral deposits in caves are called SPELEOTHEMS.

ARKENSTONE CAVE is called:

  • a WILD cave
  • a WET cave
  • a LIVE, “active” cave

What does this mean… A wild cave has no provisions for the general public and is dangerous without expert equipment and experience.  A wet cave has precipitation.

Colossal Cave Mountain Park Caves
Tower Coral, crystal formations on the floor of Arkenstone Cave

A live cave has life forms, insects, faunal, animal, species and unusual speleothems.

Pima County and Colossal Park employees have an overwhelming desire and responsibility to protect La Tetera and Arkenstone living Caves.

research caves protected in Pima County
species found in Arkenstone Cave, Colossal Mountain Park, AZ

Several new species have been found in Arkenstone that are endemic to Arkenstone, meaning they only exist in Arkenstone Cave.  A few researchers have special grants to work in these living Arizona Caves.

In recent years, 7 new species of fauna have been found.  The Arkenstone Cave exhibit at Colossal Mountain Park Museum gives detailed descriptions.

Arizona Wet Caves, Arkenstone
research at Arkenstone Cave

Animals that live in caves are often put in the category called TROGLOBITESTroglobitic species tend to be very unusual organisms.  For example, they may have loss of pigment or no eyes.  These characteristics would be adaptations to their subterranean life.

live caves in Arizona
Pseudoscorpion found in Arkenstone Cave

A previously unknown species of pseudoscorpion was discovered in Arkenstone.  The pseudoscorpion has since been listed as one of Pima County’s priority vulnerable species!

vampire bats in Arkenstone Cave
Bat Bones found in Arkenstone Cave

A small, late Quaternary, (about 2 million yrs ago), deposit of degraded bat guano (poop) in Arkenstone Cave yielded thousands of fossil bat bones.

Colossal Park living caves, La Tetera Arkenstone
Arkenstone Cave Exhibit and research

Rarer bones in the deposit represent a smaller species of bat (Myotis) and the extinct vampire bat Desmodus stocki.

This is the first record of D. stocki in what is now the Sonoran Desert and the second location for the vampire bat species in Arizona.

Rincon Mountains Arkenstone Living Cave
Extinct Vampire Bat found in Arkenstone Cave

Due to leaching in the alkaline cave environment, the bones could not be dated by radiocarbon, but the fossils probably date to the late Pleistocene Age  —  (Late Pleistocene Bats from Arkenstone Cave, Arizona by Nicholas Czaplewski and William Peachey, December 2003)

The Late Pleistocene age was dominated by glaciation  Many larger land animals, MEGAFAUNA, became extinct over this ICE AGE.  Experts estimated that 30% of the Earth’s surface was covered by ice.  Pleistocene vampire bats most likely were capable of surviving in cooler temperatures than the modern bats of today.

The extinction of Desmodus stocki paralleled the extinction of the megafauna.

Pleistoncene Ice Coverage on Earth
Photo of Earth during the Ice Age, The Pleistocene

Research indicates that Arkenstone Cave was the site of a maternity colony of Myotis thysanodes.  Myotis thysandoes is a larger species of bat, mammal.  These bats begin nursing colonies, female nurse bats remain at the roost while other adults are out foraging.

Arkenstone, La Tetera Cave Arizona
extinct vampire bat, Desmodus stocki

Virtually all of the bones collected were of that species.  Remains of Desmodus are consistent with a single individual, and those of a small Myotis (bat) consistent with two individuals (Czaplewski and Peachey 2003).

altruistic example, bats
Arkenstone Cave discovery of extinct vampire bats

Desmodus stocki was 20% larger than the still extant common vampire bat.   Lets put aside the scary name, VAMPIRE, and let me share some benevolent behavior of Vampire Bats that may gain your admiration for the Pleistocene bat, Desmodus Stocki.

Vampire Bats are one of the few animal species that show caring behavior for those beyond their family group.  They even adopt orphaned bats and will share their food.  Look at the photo above for more altruistic vampire ways.  🙂

vampire bats, Arkenstone Cave
common vampire bat skull, teeth

Scientists state that fossil records of Desmodus stocki are uncommon because these bats mainly roosted in hollow trees and any remains would decay along with the wood.

Arkenstone Cave Arizona
new species found in Arkenstone and Kartchner Caves

photo above is courtesy of  Journal of Cave and Karst Studies

A new species of Nicoletiidae (Insecta: Zygentoma) has been discovered in Arkenstone and Kartchner Caves.  This species pictured above lives in deeper areas of Arkenstone Cave than it does in Kartchner.
The 2 caves are approximately 23 miles apart and in isolated Karst areas with no possible connection to each other.
Rincon Mountains Caves Arizona
Caves at Colossal Cave Mountain Park
You would think that these would be different species?  But so far the research shows they are the same.  How amazing is that?
caves at Colossal Mountain Park in Vail AZ
Arkenstone Cave
Cave species are very fragile and some live in a specific cave and no where else in the world.   These TROGLOBITES are accustomed to a near constant temperature and humidity.  Even the slightest disturbance can disrupt the life cycles of these amazing species.
Arizona active wild caves, Arkenstone
Crystal formations in Arkenstone Cave
As updated research becomes available we will add new articles.
fringed myotis is found across the western United States.
The fringed myotis is found across the western United States. It has been found as far east as the Trans-Pecos region of Texas during summer months, as far north as British Columbia and as far south as Mexico.
The fringed myotis is found across the western United States. It has been found as far east as the Trans-Pecos region of Texas during summer months, as far north as British Columbia and as far south as Mexico.