Most venomous scorpion
Deathstalker, Leiurus quinquestriatus
Not Applicable ()

The most venomous scorpion is the deathstalker (Leiurus quinquestriatus), belonging to the Buthidae family. It has an LD50 of just 0.25 mg/kg based on subcutaneous injections given to mice. The deathstalker is distributed in arid desert and scrubland regions throughout the Middle East and North Africa.

What makes the deathstalker's venom so lethal is a potent cocktail of neurotoxins including chlorotoxin, agitoxin and scyllatoxin. While extremely dangerous, the unique chemical composition and scarcity of its venom also makes it the most valuable liquid (by volume) in the world with an estimated cost of $39 million per gallon. It is prized by the medical community because its properties have been found to be effective in the treatment of cancer, malaria and against bacteria such as tuberculosis.

Almost equal in terms of toxicity are the fat-tailed scorpions (Androctonus), also of the Buthidae family and native to North Africa. For instance, A. mauretenicus of Morocco has a documented LD50 of 0.31 mg/kg. Although slightly less toxic, Androctonus is responsible for far more human casualties than the deathstalker. The Tunisian fat-tailed scorpion (A. australis) alone is responsible for 80% of stings and 90% of deaths from scorpion stings in North Africa.

Calculating the toxicity of scorpion venom is notoriously difficult - multiple studies have found varying levels of toxicity in the same species or genus, with LD50 seeming to be impacted by many factors including the sex, age and location of the scorpion, and even how the venom is extracted.

The term LD50 represents the dose of venom that proves lethal to 50% of a test population usually expressed as milligrams or micrograms per kilogram of body weight. How the venom is administered to test subjects also dramatically affects the level of toxicity, e.g., intravenous injection is generally far more deadly than subcutaneous.