Hadrurus arizonensis

The Hairy Desert Scorpion or Great Texas Scorpion (Hadrurus arizonensis Ewing, 1928) is especially widespread in the southwest of North America (Sonoran Desert). With a body length of up to 15 cm it is the largest scorpion in the USA and one of the 8-9 Hadrurus species living there. Thanks to this size, it is able to prey on other scorpions and even small lizards and snakes. Tactile hairs and special sensory organs allow the scorpions to perceive vibrations triggered by potential prey from a distance of up to 30 cm.

These scorpions prefer semi-arid and arid steppe and desert areas and hide under stones or in self-dug burrows during the day. In order to be surrounded by optimal humidity, the depth of their burrows varies with the groundwater level of the soil. In midsummer, the animals dig up to 2.5 meters deep.

On the established four-level classification for the symptomatology of scorpion stings, stings of Hadrurus spp. are assigned to the second level (stings with severe local symptoms without systemic venom effect). Accordingly, severe and long-lasting pain is to be expected. As a reaction of the autonomic nervous system to the pain and possible fear reactions, nausea, dizziness, circulatory collapse and hyperventilation may also occur. Overall, however, the toxicity of Hadrurus arizonensis based on the LD50 value of 168-198 mg/kg for mice can be assessed as comparatively low. The toxicity of Androctonus australis (stings with cardiac and central nervous symptoms; life-threatening) with 0.32-6 mg/kg and the Mojave rattlesnake with 0.24-3 mg/kg provide a reference value. Nevertheless, this scorpion species is still two to three times more toxic than, for example, Heterometrus laoticus (LD50 value 300-600 mg/kg mouse; intensity of about a bee/hornet sting).

The animals are considered to be less aggressive towards humans compared to other species.