The Brazilian yellow scorpion is thriving in cities, causing a massive surge in stings.

Nature · Published 3 October 2026 Swipe more like this →

In short: Tityus serrulatus, the most dangerous scorpion in South America, has adapted perfectly to urban life. By feeding on cockroaches and hiding in sewers, these resilient creatures are rapidly expanding their range. As their numbers climb, so do the reported cases of human envenomation, making them a growing public health concern.

The Brazilian yellow scorpion, Tityus serrulatus, is a formidable member of the Buthidae family. Measuring between 5 and 7 centimeters, this pale-yellow predator is uniquely suited to urban environments. It thrives in sewers and trash heaps, where it finds an abundance of cockroach prey and few natural predators. Its survival is further bolstered by a low metabolic rate, allowing it to endure for months without food. Perhaps most remarkably, the species is typically parthenogenetic, meaning females can reproduce without mating, which accelerates population growth in favorable conditions.

The impact of this expansion is evident in national health data. Between 2000 and 2018, reported scorpion stings in Brazil skyrocketed from 12,000 to 140,000 annually. Experts like Rogério Bertani of the Butantan Institute attribute this trend to urbanization and deforestation, which push the scorpions into closer proximity with humans. While most stings result in localized pain, the venom is highly potent. It contains an excitatory neurotoxin that disrupts sodium channels, triggering a massive release of neurotransmitters like adrenaline and acetylcholine. This can lead to severe systemic effects, including tachycardia, hypertension, and gastrointestinal distress.

The medical consequences are significant. Mortality rates for children and the elderly range from 1.0% to 2.0%, with death typically resulting from cardiorespiratory failure or pulmonary edema. Fatalities can occur rapidly, sometimes within one to six hours of a sting. The lethality of the venom also varies by region; for instance, specimens from the Distrito Federal show a higher LD50—a measure of toxicity—than those from Minas Gerais. As the species continues to spread across states from Bahia to São Paulo, it remains the primary cause of envenomation by venomous animals in Brazil, surpassing even snakes and spiders in total incidents.

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