Rhopalurus Junceus – Detailed Guide: Care, Diet, and Breeding

Rhopalurus junceus (Cuban blue scorpion) – Detailed Guide Care, Diet, and Breeding main

Rhopalurus junceus, commonly known as “Blue Scorpion”, is gaining popularity among exotic pet enthusiasts due to its striking appearance. However, if you are a beginner or unfamiliar with this particular species, I would recommend you be extremely cautious and avoid impulsive buys.

Despite the fact that Rhopalurus junceus species is quite hardy, it is also territorial and characterized by increased aggressiveness.

If you are interested in keeping Blue scorpion or want to learn more about this species, this care guide will tell you everything you need to know, including their behavior, feeding preferences, ideal setups, how to breed and care for them.

Quick Notes about Rhopalurus Junceus

Name Blue Scorpion
Other Names
the Cuban blue scorpion
Scientific Name Rhopalurus junceus
Type
Terrestrial 
Tank size  3 gallons (12 liters)
Keeping Easy
Breeding Medium
Average size 2.2 – 4.2 inches (5.5 – 10.5 cm)
Optimal Temperature 78 – 90°F (26 – 32°C)
Water type Freshwater bowl
Moisture 65 – 85 %
Substrate Any
Diet Carnivore  
Temperament Semi-aggressive 
Life span up to 5 years
Color Form Нellowish-brown to reddish and dark

Interesting fact: The venom is used in the research of active components for biomedicine. Additionally, its venom has become a very popular treatment in traditional medicine in Cuba for pain and inflammatory diseases.

Taxonomy of Rhopalurus Junceus

The genus Rhopalurus consists of five species, of which four are endemic to Cuba.

  • Kingdom: Animalia (Animals)
  • Phylum: Arthropoda (Arthropods)
  • Subphylum: Chelicerata (Chelicerates)
  • Class: Arachnida (Arachnids)
  • Order: Scorpiones (Scorpions)
  • Family: Buthidae (Buthid Scorpions)
  • Genus: Rhopalurus
  • Species: Junceus

Etymology of Rhopalurus Junceus

The genus name “Rhopalurus” is derived from the Ancient Greek words ” ῥόπαλον” which means “Club or knob” and “ourā́” meaning “tail.” It refers to the characteristic club-like shape of the metasoma (tail) that scorpions, including Rhopalurus junceus, possess.

The specific name “Junceus” comes from the Latin word “Junceus,” which translates to “Rush” or “Reed.” In the context of the scorpion’s name, it may be associated with the color or appearance of the species, possibly reflecting the blue hue.

Distribution of Rhopalurus Junceus

Rhopalurus junceus (Cuban blue scorpion) – Detailed Guide Care, Diet, and Breeding DistributionRhopalurus junceus is an endemic species from Cuba where these scorpions are widely distributed over most of the archipelago.

Note: Despite being initially described in scientific literature as inhabiting Brazil and several other countries (such as Mexico, Haiti, Venezuela, the Dominican Republic, and Puerto Rico), this species has not been subsequently found in any of these countries.

Habitat of Rhopalurus Junceus

This species lives practically everywhere: semi-deciduous and evergreen forests, cloud forests, swamp forests, mountain rainforests, coastal and subcoastal shrublands, cactus scrubs, mangroves, pine forests, coastal sandy and rocky areas, etc.

They can be usually found in both canopies and caves (under rocks and logs) on the ground.

Description of Rhopalurus Junceus

This is not a large species. The size of adults varies, ranging from 2.2 – 3.5 inches (5.5 – 9.5 cm) in males and 2.6 – 4.2 inches (6.5 – 10.5 cm) in females.

Note: In their natural habitat, larger specimens are mostly found in wooded areas and human-altered places like shrublands and secondary grasslands. The smaller individuals are typically from thorny shrublands on serpentinites in the central area.

Rhopalurus junceus (Cuban blue scorpion) – Detailed Guide Care, Diet, and Breeding profileDistinguishing characteristics:

  • Color. This species has two color morphs: yellowish-brown to reddish and dark. It is slightly lighter on the legs, ventral region, and posterior margin of the carapace and tergites. The metasomal segment III and telson are dark reddish-brown. The metasomal segments IV-V and the distal half of the aculeus are blackish. Fingers are black with yellowish tips.
  • Carapace. The carapace is finely and densely granulated, with scattered larger granules. The anterior median and posterior marginal (grooves) are very wide and shallow. The central lateral and posterior lateral are narrow and shallow.
  • Eyes. The median eyes are normal-sized, they are separated by a little more than their diameter. There are five pairs of lateral eyes: three pairs of medium size and two smaller pairs.
  • Prosoma and tergites. The prosoma and tergites are finely and densely granulated, with scattered coarse granulation.
  • Metasoma. The metasoma has 10-8-8-8-5 complete keels; segments IV-V are moderately to strongly thickened in males, with subparallel sides in females.
  • Telson. The telson has an oval vesicle and no subaculear tubercle (juveniles have a progressively reducing spine-like tubercle with development).
  • Claws. Pedipalps with robust manus are wider than patella in both sexes, and moderately to strongly thickened in males. Manus and fingers have dense hirsute covering; fingers are curved and moderately to strongly separated at their basal portion in males, nearly glabrous and contiguous in females. Moveable finger has a strong basal lobe in adults of both sexes (more developed in males).
  • Pectines. In males, pectines have 17-23 teeth. Females have 15-21 teeth. They are yellowish to whitish.

If you need a more detailed description in scientific terms, you can read it here.

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Lifespan of Rhopalurus Junceus

Depending on the temperature and conditions, Rhopalurus junceus generally live for 3 – 5 years. Their short lifespan is closely correlated with their fast growth.

Typical Behavior of Rhopalurus Junceus

Activity. Rhopalurus junceus exhibits typical behaviors for the scorpions. It is nocturnal, meaning it is primarily active during the night. However, it does not mean that you will never see them in the daytime. They are simply less active during this time.

This species is fast and quite active, frequently moving about its environment.

Burrowing behavior. Although Rhopalurus junceus is not a typical burrower, it often excavates short galleries along the lower contour of rocks, logs, or other objects if they are too close to the ground. In rocky wall crevices, it periodically expels accumulated soil, debris, and remnants of consumed prey.

Territoriality. In their natural habitat, populations are generally dispersed over a wide area and of moderate size. However, they can occasionally reach high densities in specific locations such as the humid forests of the Sagua-Baracoa mountain range and the savannas in central Camagüey.

Nonetheless, Despite this, these scorpions exhibit pronounced territorial behavior. Even in high-density areas, like stone and debris accumulations in cattle pastures, it is rare to find two or more individuals together unless they are of opposite sexes.

Sociality. They are solitary. Cannibalism is very common in this species. Observations in nature include cases of adult females devouring juveniles, possibly linked to their marked territorial behavior.

Hunting Behavior. It is an ambushing predator that emerges from its shelter at night and patiently waits for potential prey to pass by.

Noisy. Rhopalurus junceus can make a loud sound that can be heard from several meters away. It is a primary defensive response, often triggered when discovered or physically disturbed. Sometimes, it also happens during mating, but scientists are not sure why or which partner is responsible.

Features:

  • Communal: No
  • Activity: Average
  • Peaceful: Semi-aggressive
  • Burrowers: No
  • Climbers: Yes
  • Venomous: Yes

Venom of Rhopalurus Junceus

Rhopalurus junceus belongs to the genera Rhopalurus included in the Bhutidae family which includes the most dangerous species related to humans.

The good thing though is that experiments indicated that these scorpions have low enzymatic activity, which could contribute to the low toxic potential of this scorpion venom.

Note: According to the study, the soluble venom of this species is not toxic to mice, injected intraperitoneally at doses up to 200 mg/20 g body weight, but it is deadly to insects at doses of 10 mg per animal.

Nonetheless, the sting of Rhopalurus junceus is still extremely painful, causing immediate intense local pain followed by cramps and stabbing sensations radiating from the site of inoculation and extending considerably over the body.

For example, if the sting occurs on a finger, the effects can encompass the entire affected limb and the adjacent part. These effects can last for about 4-8 hours and gradually give way to a complete absence of sensitivity around the sting site, persisting for 2-3 days.

Despite the severity of these symptoms, in Cuba, there is no report of fatal sting from this or another species in the country. However, some patients have required hospitalization or medical treatment due to the severity of their reactions.

If you are keeping Rhopalurus junceus as pets, especially in households with children or elderly individuals, it’s essential to take precautions and DO NOT allow children to touch Rhopalurus junceus!

Always remember that keeping scorpions as pets requires responsible ownership and awareness of potential risks.

Diet of Rhopalurus Junceus

Rhopalurus junceus is an opportunistic predator. In its natural habitat, this species on various arthropods such as ants, crickets, cockroaches, centipedes, spiders, amblypygids, other scorpions, and even on small vertebrates such as geckos of the genus Sphaerodactylus.

In the terrarium, the acceptable food items include:

  • crickets,
  • mealworms,
  • dubia roaches,
  • red runner roaches,
  • moths,
  • worms, etc

Interesting fact: They use sensory systems (long and very thin sensory hairs located all over the body) other than vision to locate prey.

How Often to Feed Rhopalurus Junceus?

Feeding Rhopalurus junceus once a week or two is recommended.

Juveniles may require more food (2 – 3 times per week).

Some Important Feeding Tips:

  • Time. Rhopalurus junceus is nocturnal. Therefore, it is highly recommended to feed them at night (at least in the evening). By doing so, you will replicate the conditions and environment under which they eat naturally.
  • Prey size.  Ideally, their food should not be larger than their stomach. Large prey may harm the scorpion.
  • Prey activity. Never give them prey that can fight back aggressively. Additionally, do not give them prey that will burrow, jump, or fly around their enclosure. For example, remove the wings, chop the forelimbs, break the legs, or squash the head so that they wiggle and are easily accessible to the scorpions.
  • Refuses to eat. Do not leave the live food in the enclosure. If your scorpion does not want to eat you need to remove it the next day. Do not worry, if your scorpions do not eat. Actually, they may not even eat every month! Thus, try again in a week.
  • Check the hiding spots. Keep in mind that scorpions often drag and store food in their hiding spots for later consumption. Check them from time to time to prevent any mold, mites, or bacterial contaminations. If it is not eaten in 2 days, remove it.

Features:

  • Diet Type: Carnivore
  • Food Preference: Alive prey.
  • Feeding Frequency: 1 time a week (for adults) and 2 – 3 times a week (for babies)
Rhopalurus junceus eat their prey alive. So, if you are a sensitive person, you should not keep them as a pet.

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Keeping and Housing Rhopalurus Junceus

Tank size:

The minimum size of the enclosure for the Cuban blue scorpion should correspond to the length of the scorpion’s body. Here are the recommended minimum dimensions:

  • Length of the enclosure = twice the length of the scorpion’s body.
  • Width of the enclosure = one and a half times the length of the scorpion’s body.
  • Height of the enclosure = the same as the length of the scorpion’s body.

but only if the setup allows for the necessary temperature and humidity to be created and maintained

Ideally, it will be better to keep it in a 3 or 5-gallon (12 – 20 liters) enclosure. In a larger tank, it can be easier to make diverse areas for them to hide.

The only problem that may arise with a larger enclosure is that during feeding, their prey can run and hide from the scorpions for quite some time, given that scorpions are not active hunters.

IMPORTANT: Make sure that the tank has a secure lid to prevent the scorpions from escaping!

Temperature:

Rhopalurus junceus prefers temperatures between 78– 90°F (26 – 32°C). However, they can tolerate very low temperatures as well. For example, this species is also found in mountainous areas (in the Habana-Matanzas plain), with temperatures below 41°F (5°C) recorded nearly every year.

According to the study, during some experiments, about 20 juveniles of these scorpions were accidentally exposed to -32°F (-18°C) and froze completely. One of them even lost metasoma upon handling because they became so rigid. However, half an hour under a heat lamp revived them, showing remarkable resilience to freezing.

Humidity:

The ideal humidity level for Rhopalurus junceus is between 65 – 85 %.

Cuba has a diverse climate, and humidity can vary across different regions and months. For example, in the north during the dry season, it might range from 65% to 75%, while in the south during the rainy season, it can be between 80% and 90%.

Tip: One of the easiest ways to keep the humidity up is to use lots of sphagnum moss inside their enclosure.
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Water:

Scorpions typically don’t drink water directly from bowls because they get most of their water from their food. Nonetheless, it is still recommended to give Rhopalurus junceus access to water through a dish anyway.          

Even a small plastic bottle cap will be enough. Fill it 1-2 times a month and let it evaporate dry.

Ideally, we need to give them something like bottled spring water. But if you decide to use tap water, let it age for 24 hours before using it. Tap water contains chlorine and it can be toxic to them. 

Light:

No special requirements.

Rhopalurus junceus is nocturnal. Thus, ambient light will be enough.

UV lighting

Rhopalurus junceus glows under black light. Blacklight is also an option to make the environment safe in the house while there is a scorpion living. It can help in locating the scorpion if it escapes its cage.

However, UV lighting is not completely safe for scorpions. It stresses them. The point is that ultraviolet is simply a normal part of the light from the sun. These scorpions do not like to be exposed to the sun.

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Substrate:

No special requirement.

Rhopalurus junceus is not an obligate burrower. This species of scorpion does not exhibit a strong instinct and need to create and inhabit burrows as part of its natural behavior. However, they can do that.

Basically, you can use anything (soil, gravel, clay, etc.). However, if you have problems with keeping your humidity high, it will be better to use:

  • coco fiber (Eco earth),
  • peat moss,
  • organic topsoil,
  • Jungle mix soil,
  • Zoo Meds Creatures Creature soil,
  • Reptisoil,
  • The Bio Dude Terra.

These types of substrate are good for maintaining water which helps to stabilize humidity. Therefore, the substrate should always be kept moist enough. It means that it should hold its shape when you squeeze it. However, not so wet that it drips or pools water.

In my opinion, the simplest and cheapest way is to just use coco fiber.

Important: Do not use only sand! Sand often becomes supersaturated even though the top couple of inches are completely dry.

Hiding places:

In their enclosure, make sure to provide plenty of dark hiding spots using rocks, stones, and other decorations to enrich their environment.

Shelter is a primary necessity for scorpions, making decorations in their enclosure crucial for their well-being. So, the more decorations you have, the happier your pets will be.

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Handling Rhopalurus Junceus

Rhopalurus junceus are venomous scorpions. While their venom is not considered life-threatening to humans, it is still highly painful. Therefore, exposing yourself to unnecessary risks is not advisable.

Remember that scorpions are not harmless pets and should be treated with caution and respect.

They are not pets you can play with!

It’s not advisable to take them out just because you want to. The scorpions do not benefit from being handled, and they easily get stressed. Therefore, it’s best to handle them as little as possible.

However, if you must take them out, it’s preferable to use rubber gloves and follow these steps:

  1. Put your hand slowly in front of the scorpion.
  2. Nudge it from any side using a brush or pen.
  3. The scorpion will turn around to face the “threat.”
  4. Nudge and slightly push it until it backs up onto your hand.
  5. Avoid pressing it down since scorpions dislike it. DO NOT ever pick them up by the tail or touch them from the rear.

Breeding Rhopalurus Junceus

Breeding this species in a terrarium may be accompanied by certain challenges, primarily associated with their territorial behavior and aggression.

Females may reject males very aggressively, without ever engaging in courtship.

Maturity:

Rhopalurus junceus grows really fast. Under optimal temperature, males reached adulthood from nymphs IV and V with an average size of 58 and 73 mm, respectively, while females only did so from nymph V with an average size of 80 mm.

The total duration of the juvenile stage may range from 228 to 341 days.

Mating:

Before placing a pair of adult scorpions together, it is important to ensure that they are well-fed. The container in which mating will occur should be spacious enough to accommodate a piece of flat stones to which the male can attach the spermatophore:

  • the male uses its pedipalps to grasp the female’s pedipalps to guide the female over a spermatophore during mating;
  • the female usually follows the leading male in a classical promenade until a suitable spot is found for spermatophore deposition;
  • then, the male assists the female in positioning her genital aperture over the spermatophore;
  • after that, the pair separates.

Overall, it is generally believed that this species requires mating for offspring reproduction. At the same time, scientists also observed a female that produced two broods after a single insemination.

Interesting fact: According to the study, this species also exhibits pre-copulatory cohabitation behavior: adult males recognize pre-adult females who are a few days away from their last molt, stay close to them, and promptly try to mate once they molt.

Gestation:

Depending on the temperature and feeding, females have gestation periods from 80 to 100 days.

Fecundity:

Females of Rhopalurus junceus give birth to an average of 20-30 neonates (nymphs or scorplings).  During this study, 47 litters were obtained, with quantities ranging from 14-55 neonates.

Scorplings:

Rhopalurus junceus exhibits maternal care by carrying offspring on their backs. Unlike juvenile scorpions and adults, scorplings have suckers on their legs, which allow them to move confidently and easily cling to the mother’s body.

When scorplings are with the mother, there is no need to feed baby scorpions, their mother will take care of that. Just give her more food than you normally would. She will catch the prey, tear it apart, and let the babies feed on it.

It takes them 5-8 days to molt. After that, in another 1-3 days, they will leave her and become independent.

Important: Once babies leave the mother’s back, it will be better to separate them from her and each other as well.

Interesting fact: It was noticed that a female can give birth to both morphs (black and light) juveniles.

Scorplings growth rate:

Ecdysis  Days
1st molt 5-8
 2nd molt 60-80
3rd molt 30-40
4th molt 80-140
5th molt 70-100

Rhopalurus Junceus and Suitable Tankmates

None.

It is not recommended to keep these scorpions with other scorpion species or even conspecifics. They are too territorial and aggressive.

In Conclusion

Rhopalurus Junceus is a very interesting, beautiful, and unusual scorpion.

However, I would strongly advise against choosing it as your first pet, primarily due to its small size, venomous nature, and difficult temperament.

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References:

  1. Dioguardi, Mario, Giorgia Apollonia Caloro, Luigi Laino, Mario Alovisi, Diego Sovereto, Vito Crincoli, Riccardo Aiuto et al. “Therapeutic anticancer uses of the active principles of “Rhopalurus junceus” Venom.” Biomedicines8, no. 10 (2020): 382.
  2. Díaz-García, Alexis, Jenny Laura Ruiz-Fuentes, Arianna Yglesias-Rivera, Hermis Rodríguez-Sánchez, Yanelis Riquenes Garlobo, Osmel Fleitas Martinez, and José A. Fraga Castro. “Enzymatic analysis of venom from Cuban scorpion Rhopalurus junceus.” Journal of venom research6 (2015): 11.
  3. García-Gómez, B. I., F. I. V. Coronas, R. Restano-Cassulini, R. R. Rodríguez, and L. D. Possani. “Biochemical and molecular characterization of the venom from the Cuban scorpion Rhopalurus junceus.” Toxicon58, no. 1 (2011): 18-27.
  4. Teruel, Rolando, and Luis F. de Armas. “Redescripción de Rhopalurus junceus (Herbst 1800)(Scorpiones: Buthidae).” Boletín de la Sociedad Entomológica Aragonesa50 (2012): 153-174.
  5. Rodríguez-Cabrera, Tomás M., Rolando Teruel, and Leosveli Vasallo-Rodríguez. “Iteroparity following single insemination and largest size litter in Rhopalurus junceus (Herbst, 1800)(Scorpiones: Buthidae).” Revista Ibérica de Aracnología26 (2015): 75-77.
  6. Teruel, Rolando, and František Kovařík. Scorpions of Cuba. Jakub Rolčík-Clairon Production, 2012.
  7. Rodríguez-Cabrera, Tomás M., Carlos A. Martínez-Muñoz, and Rolando Teruel. “Predation by the scorpion Rhopalurus junceus (Scorpiones: Buthidae) on the centipede Scolopocryptops ferrugineus (Scolopendromorpha: Scolopocryptopidae).” Revista Ibérica de Aracnología26, no. 1 (2015): 85-86.

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