Bark Scorpions (genus Centroides)

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By Dean Gramcko

Bark scorpions are a unique and fascinating group of scorpions indigenous to the Americas that are ideally suited to captive care in the vivarium. In America, the term Bark scorpion commonly denotes members of the genus Centruroides, a genus of Buthidae with between 70 and 80 species (different authorities disagree on certain species status). The genus Centuroides is an American taxon spanning the United States, Mexico, and Central America with established populations in South America and the West Indies, and smaller introduced populations in Africa.

The species of this genus are non-burrowing and hide among leaf litter, under stones or wood, among dead or living vegetation, or in the folds of plants or tree bark. Many species find their way into human habitations in their native areas. They are light bodied and agile,0 and able to climb vertical surfaces or cling upside down to rough surfaces as they walk. A number of Centruroides species have very potent venom. Due to their defensive nature and frequent encounters with humans some Centruroides species are responsible for numerous deaths or dangerous envenomations in their native countries. C. exilicauda, C. sculpturatus, C. limpidus, C. noxius, and C. suffusus all possess venom documented as having caused humans deaths, other species within the genus may possess medically significant venom. Many species within the genus possess venom capable of inflicting strong pain, but are not considered to have particularly toxic venom. Any species of Centruroides must be kept in an escape proof cage. A tight fitting lid is a must for any enclosure, as small gaps between lids and enclosures can provide perfect opportunities for escape. Some keepers apply a band of petrolium jelly around the upper lip of the cage to help prevent young or small specimens from escaping.

Bark scorpions, like many Buthids, have a relatively short life cycle when compared to many other species. Specimens of C. guanensis may reach maturity in as little as 6 months, (most groups of scorpions take at least 1 to 2 years to mature, some species take much longer). They, as a group, are generally short lived with reported lifespans of between 1 year (C. insulanus) and over 4 years (C. gracilis). Most species within the genus Centuroides do not have established longevity records, but with maturation taking up to 3 or 4 years in C. vittatus, it is not unlikely that some specimens within the genus might live 6 years or more.

Bark scorpions are well suited to life in a vivarium. They are small in size (many measure less than 3” in length) and are one of few types of scorpions that can be housed communally with minimal chances of cannibalism. They are active hunters and as they do not burrow they are an ideal species to observe in the evenings. Most Centruroides species kept in captivity have proven to be prolific, and usually if males and females are housed together under proper conditions for long enough they will produce offspring. Bark scorpions are iteroparous and may give birth to between 1 and 4 clutches after a single mating, 2 probably being about average.

3 commonly available species are:

Centruroides sculpturatus: commonly called the Arizona Bark Scorpion, C. sculpturatus is generally considered to have the most potent venom of any U.S. scorpion, and while deaths are rare, it is the only U.S. scorpion that is well documented as having caused deaths not related to allergic reactions. It was formerly considered to be the same species as C. exilicauda, a Mexican species of bark scorpion now considered to be a separate species.

Centruroides vittatus: commonly called the Texas Bark Scorpion or Striped Bark Scorpion, this is a distinctively marked species that is frequently available and common in the U.S.

Centruroides gracilis: This scorpion likely hails from Central America originally but has well established populations in Florida in the United States as well as Islands in the Caribbean. It is among the largest bark scorpions with adults measuring from between 4 and 6 inches.

Most species of bark scorpions kept in captivity do well under relatively similar conditions with varying temperature and humidity depending on species. Most specimens will thrive in a terrarium when given stacks of cork bark or stones to hide under. Care should be taken to ensure that cage furnishings will not shift and crush any scorpions. Live plants such as bromeliads or non-spiny succulents can improve the look of the enclosure (any plant used should be identified and researched to ensure it doesn't present a threat to the scorpion), and provide hiding places for the scorpions. Water should be provided to any species at all times in a dish shallow enough to ensure scorpions do not become trapped and drown. Adding gravel to smooth bottomed dishes can help to guard against drowning. Most bark scorpion do well under similar temperature ranges (75 - 87 Fahrenheit). Most species do not require high humidity levels. Misting the enclosure lightly once weekly or bi-weekly depending on species is recommended.

Baby bark scorpions can be housed either in the larger enclosure with the adults, (though adult scorpions may sometimes cannibalize the young) or separated and raised up in small deli cups. The author prefers individual deli cups as it allows more precise control of temperature and humidity and eliminates any chance of predation from larger cagemates. Juvenile bark scorpions development is measured most commonly with the term “instar” (referring to the stage of development present between two molts).

A newborn scorpion is termed “1st instar”. Upon completion of it’s 1st molt it is considered “2nd instar”. The precise number of molts preceding adulthood varies between species and sometimes between genders of the same species. Generally bark scorpions seem to mature at around their 6th or 7th molt which for most Centruroides species occurs within 1 or 2 years (though some species may take much longer).

Their semi-arboreal nature, ability to live communally, and their readiness to reproduce in captivity make this group of scorpions fascinating to keep and an ideal candidate for observation in a vivarium. While the lifespan of individual scorpions are relatively short, these communal scorpions can be set up in large breeding colonies that will bring satisfaction to their keeper for years.

References:

Francke, O.F. & Jones, S.K., 1982. The Life History of Centruroides Gracilis (Scorpiones, Buthidae). The Journal of Arachnology, Vol. 10, pp. 223 - 239.

Polis, G. & Sissom, W.D., 1990. Life History. In G. Polis (Ed.), Biology of Scorpions (pp. 161 - 223). Stanford, CA: Stanford University Press.

Rein, J.O. & Teruel, R., 2012. The Scorpion Files. Retrieved from http://www.ntnu.no/ub/scorpion-files/c_gracilis.php

Sissom, W. D., 1980. Life Histories of Two North American Scorpions: Centruroides vittatus (Say) (Buthidae) and Vaejovis bilineatus Pockock (Vaejovidae). Masters dissertation. Texas Tech University, Lubbock, TX.

Stahnke, H.L., 1971. Some Observations of the Genus Centruroides Marx (Buthidae, Scorpionida) and C. Sculpturatus Ewing. Entomological News, Vol. 82, pp. 281 - 307.

Stahnke, H.L. & Calos, M., 1977. A Key to the Species of the Genus Centruroides Marx (Scorpionida: Buthidae). Entomological News, Vol. 88, pp. 111 -120.