How to kill the most dangerous scorpion in Brazil

 As I discussed last time, the Brazilian Yellow Scorpion (BYS) has an incredibly powerful sting, fatal to humans in hours. And it’s numbers are increasing in cities in Brazil, for various reasons, but mainly because it feeds on cockroaches and flies, more rubbish means more food, so more scorpions. And also the absence of natural enemies (see below).

So how do you control it? Well they are quite small, but I strongly warn against treading on one! Insecticides can work, Bifentol for example can kill them, but BSYs can survive for up to 400 days without food, as long as they stay wet, and it’s hard to spray everywhere. When they do reproduce, which they can do at any time in the year, they are quite fertile.

Surprisingly, there are natural enemies. Hens will voraciously feed on BYS’s though they are well aware of the sting, and apparently survive. They even prefer them to corn (“hmm, spicy”). In 1922 the mayor of Aparecida in Brazil distributed chickens as a way of attempting to control a scorpion outbreak.

But the true Nemesis of the Brazilian Yellow Scorpion is a toad, Rhinella icterica. Quite a common toad in southern Brazil, living in forests and Cerrado savanna, in the wild R. icterica tends to live in the same environments as BYSs, and both are active at night. They appear to be more or less immune to the scorpion sting and will happily hunt and kill scorpions. 

Photo conveniently showing the different coloration of male and female Rhinella icterica. Wikimedia Commons - Caio Biasoli

None of this however helps in the city. At a domestic level advice is remove any food sources which might attract cockroaches and seal any cracks in walls, especially in damp areas. Put down insecticides or sticky traps. And, anecdotally, tip out shoes before you put them on - and run a shower for a few minutes before entering, scorpions like damp, dark places and are quite capable of crawling up the drains!
 

Jared C, Alexandre C, Mailho-Fontana PL, Pimenta DC, Brodie ED Jr, Antoniazzi MM. (2020). Toads prey upon scorpions and are resistant to their venom: A biological and ecological approach to scorpionism. Toxicon., 178:4-7.

Murayama GP, Pagoti GF, Guadanucci JPL, Willemart RH. (2020). Voracity, reaction to stings, and survival of domestic hens when feeding on the yellow scorpion (Tityus serrulatus). J Venom Anim Toxins Incl Trop Dis., 28:e20210050

Murayama GP, Barbosa B, Willemart RH (2023). Experimental approach to the dislodging effect and the mortality of a pesticide in the yellow scorpion Tityus serrulatus. PLoS ONE 18(7): e0289104.