Hadrurus arizonensis

(Ewing, 1928)

Today's subject is Hadrurus arizonensis (Ewing, 1928). The generic name, Hadrurus, is from the Greek words hadr-, meaning "thick," and ur, meaning "tail." The specific name, arizonensis, is a place name meaning "of, or belonging to," (-ensis) the state of Arizona, U.S.A.

Hadrurus arizonensis
Vital Stats:
  • [not available]

This scorpion is in the family Iuridae and belongs to the subfamily Hadrurinae. Currently recognized subspecies include: Hadrurus arizonensis arizonensis Ewing, 1928, Hadrurus arizonensis pallidus Williams, 1970, and Hadrurus arizonensis austrinus Williams, 1970. This scorpion exhibits a variety of different forms and color morphs and almost certainly represents a cryptic species complex. Don't forget to check out the high resolution JPEGs for Hadrurus arizonensis arizonensis and Hadrurus arizonensis pallidus.

Original Description: Ewing, H.E. 1928.

The scorpions of the western part of the United States, with notes on those occurring in northern Mexico. Proceedings of the U.S. National Museum, 73:1-24.


Hadrurus arizonensis is found in extreme southern Utah and Nevada, southern California, and western Arizona in the United States. It is also found in northeastern Baja California and northwestern Sonora in Mexico. Hadrurus arizonensis is generally restricted to desert vallies throughout its range. Like many of the desert scorpions, it is an obligate burrower. During the summer, however, individuals may be found under rocks, logs, sleeping bags, and other surface objects.

Fun Facts

Members of the genusHadrurus are the largest scorpions found in North America. Though defensive when first encountered, I have found them to be among the easiest scorpions to handle both in the field and in the lab. The venom of these large scorpions is not considered to be particularly potent, but they can do considerable damage if improperly handled. As always, certain human individuals may be allergic to the venom and can experience life threatening side effects when stung (as occurs with bee stings). Did you ever wonder why so many scorpions have a dark crescent running from one set of lateral eyes through the median eys and over to the opposite set of lateral eyes? (It keeps me awake at night!) My best guess is that the coloration provides camouflage for the animal as it sits at the opening of its burrow. See, the opening of a scorpion burrow is semi-circular or crescentic in shape. At dusk, the scorpion creeps up to the burrow opening and positions his carapace so that the interface between the fading sunlight and the shadow of the burrow falls directly across both lateral eye groups. Thus, the light part of the carapace (directly in front of the dark crescent) is in the light (but it blends in with the desert sand) while the dark crescent and the rest of the body is in the shadow of the burrow. As a result, there is no break in the light/shadow interface. As the light fades, and the shadows lengthen, the scorpion moves further out of the burrow.

Disclaimer: The views expressed here are mine alone and do not represent the views of the Department of the Army or the Smithsonian Institution... or anybody else for that matter. – Dr. Scott A. Stockwell

The Walter Reed Biosystematics Unit | Museum Support Center, MRC-534 | Smithsonian Institution | 4210 Silver Hill Rd. | Suitland, MD 20746-2863 USA | Ph: 301-238-1077; FAX: 301-238-3168
Entomology Branch | Walter Reed Army Institute of Research | 503 Robert Grant Avenue | Silver Spring, MD 20910-7500 USA

WRAIR logo  Smithsonian Institution logo © Smithsonian Institution  | Privacy | Terms of use | Contact WRBU