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I’ve seen a lot of beginner Heterometrus keepers asking similar questions. I thought it might be a good idea to make a thread answering the most common questions and adressing some of the most common issues I see with beginner Heterometrus keepers. Hopefully this will make it easier for them to find answers, and the link can be shared if it’s relevant to a question that is asked.
Basic care:
Heterometrus spp. can be kept really similarly to the Emperor scorpion (Pandinus imperator) for which there already is a caresheet on the forum. There are some other ways of setting up the enclosure, but the enclosure described here is practical and easy: https://arachnoboards.com/threads/basic-emperor-scorpion-p-imperator-care.11336/
You can also set up the enclosure without the gravel layer on the bottom, but make sure that the substrate stays damp enough! I will write about this in more detail in the next paragraph.
Some examples of enclosures for Heterometrus sp.:
A simple enclosure for a small scorpling Heterometrus. Thanks to @Edan bandoot for sharing this picture.
A simple enclosure for a juvenile Heterometrus.
A live planted bioactive enclosure for a large Heterometrus. An enclosure doesn’t have to be live planted to be good though.
1. Common mistakes/issues:
Moisture
I’ve seen a lot of people keeping their Heterometrus too dry. Moisture is one of the most important aspects of keeping Heterometrus species. They come from tropical rainforests in Asia, where they have very regular access to water. This means their transpiration rate (water loss) is much higher than the more arid species. To accomodate for this, the humidity in the enclosure needs to be high, because water will tend to diffuse to areas where there is little water, meaning dry air will essentially suck moisture out of the scorpion. This won’t happen as much with humid air.
Exact humidity numbers aren’t important. All that matters is that the substrate is damp all throughout. This is done by mixing the substrate with water before putting it in the enclosure, and regularly add some more water when you notice it starting to dry out. The most effective is pouring a bit of water directly into the substrate. Substrates tend to look a bit darker when damp, making it easy to see when watering is needed. Of course, you don’t want it dripping wet, just damp. Water from the substrate will then slowly evaporate into the air, making it more humid. The most humid part will usually be under the hides (cork bark, wood, tunnels made by the scorpion itself), because the humid air is trapped there.
To make sure the humid air doesn’t leave the enclosure immediately, and the substrate doesn’t dry out too quickly, it is a good idea to restrict ventilation. A standard exo terra, or an aquarium with a mesh lid, won’t hold humidity very well. If you cover a significant portion of the mesh, the humidity is trapped a lot better.
It is also important to offer a water dish that is always filled, so that the scorpion can have a drink once in a while. If the scorpion spends a lot of time in or around the water dish, the enclosure is likely too dry, or it is too hot. Make sure the scorpion cannot drown in the dish. Especially for younger scorpions, it may be a good idea to add some gravel to the waterdish, preventing drowning. A sponge in the water dish is not a good idea, but because it is still common, I will make this a separate paragraph.
Sponge in waterdish
An issue I see with some beginners, is using a sponge in the water dish. This is often recommended by pet stores, but is a bad idea! Sponges are a really good medium for bacteria to grow on, due to the high surface area caused by the open-cell structure. This means the scorpion has to drink from a bacteria infested sponge. You’re better off taking the sponge out. If you worry about the scorpion drowning, you can add some gravel to the water dish or use a shallower dish. Especially for small individuals.
Temperature
Regarding temperature, I would recommend keeping it between 24-30 C (75-85 F). At night, it is fine to let it drop to around 20 C (70 F). If you keep them cooler, the metabolism of the scorpion will be compromised, meaning it won’t eat and grow much.
If you live in a cooler climate (or in an air-conditioned room), you need heaters to achieve these temperatures. The enclosure can be heated with a heat mat, heat cable or a lamp. Heat mats and heat cables don’t work when there is too much ventilation for the heat to escape, as they heat more slowly. This shouldn’t be an issue, because if you read the moisture paragraph, you know that you don’t want too much ventilation anyway. Another thing that is important when using heat mats/cables is that you don’t put them on the bottom, but on the side. Since Heterometrus are burrowing scorpions, they will dig deeper when they feel to warm. Heating from the bottom, they cannot escape the heat by burrowing down, as they will only get warmer. Another issue when heating from the bottom, is that the heat can’t escape because of the deep substrate. This might cause burn marks on the surface the tank is placed on, and could even break the glass of the tank. This is why heat mats/cables should be put on the side of the tank. If needed, you can put isulation behind it so that more heat is pushed in the tank. If it gets too hot, use a thermostat.
When using a lamp, make sure the wattage is not too high.
The easiest way to measure temperature is with an infrared heat gun. These are also quite accurate. Digital thermometers with a probe are also usually accurate.
Wild caught vs. captive bred
What a lot of people don't realize, is that the vast majority of Heterometrus sp. being offered, are actually imported from the wild. This goes for a lot of other scorpion species as well, more or less depending on where you live. The scorpions were caught by people that will do anything to earn some money, in a country where the average income is generally low. This makes it really cheap to collect them, and ship them in large quantities to mainly Europe and North-America, among other places. The collected scorpions are usually (sub)/adult. There are a few issues associated with wild caught Heterometrus (as is the case with any imported animal).
In between catching them and them arriving at the pet store/seller, little attention is put into the animals. They are kept in large amounts, in small boxes, with probably little water available. When they arrive here, they're stressed and dehydrated. They also may carry parasites. In the wild, parasites are usually not a big issue, but when exposed to stress, their immune system gets compromised and the parasites may grow in population. All this causes animals to die before arriving here. When they do arrive here, they arrive at an importer. Many importers don't put a lot of effort into the animals either. After that, they finally arrive at the pet store/seller. Some sellers provide proper care, many don't. So even after arriving, not all animals will make it. So you have to realize that when you buy an adult Asian forest scorpion from a pet shop or general invertebrate/reptile seller with no specification on where it came from, it's almost certainly an imported individual that must have had a long journey and needs a lot of time and proper care to recover. Speaking from experience, wild caught animals are much less stable and may just crash suddenly. This is the case for many species of animal, and scorpions are no exception. With Heterometrus, this is not only caused by complications due to the transport process, but also due to the fact that it's usually adults being imported, so the age is unknown.
Another important thing to realize with wild caught animals, is the environmental impact. Heterometrus species are so popular, that there are way more animals being taken from the wild than the population can reproduce. Asian forest scorpions have a very long gestation period and they aren't the quickest growers, so at the current rate, there is no time for populations to recover. Some species that used to be popular, like the emperor scorpion (Pandinus imperator) and the flat rock scorpion (Hadogenes troglodytes), are now very rarely imported because the countries of origin put restrictions in place on their export. This is because the effects were starting to become very serious.
Although the scorpions are still being imported and sold for very cheap, and their reproduction takes a lot of time, which makes it a not very attractive breeding project, there are fortunately more and more people breeding Heterometrus species. When young Heterometrus are being offered and the seller specifically states they are captive bred, those animals are the best Heterometrus to buy. These are usually sold by specialized small scale sellers or hobbyist breeders, whereas bigger companies usually have the wild caught adults.
And when you get a bit more experience with Heterometrus, and you're sure what species you have (they're often sold under wrong names), it would be great if you could do your part by breeding them!
I strive to buy all my scorpions captive bred (and I have a lot, so it can be done) and I recommend everybody to do the same.
2. Common questions:
What sex is my Heterometrus?
Heterometrus species can be sexed by looking at the underside. Here you have the pectines (2 elongated structures with “teeth”) and the genital operculum (the little plate above where the pectines connect).
In females, the genital operculum points more to the rear end of the scorpion, creating kind of a heart shape. The pectines and pectine teeth are usually smaller.
In males, the genetal operculum points more towards the front end of the scorpion, creating kind of a spear shape. The pectines are often longer with bigger teeth.
With some Heterometrus species, the chela (pincher) shape is different between sexes, but this is not the case for all Heterometrus. With Heterometrus silenus, the most common species, there will be little to no difference in chela shape.
If you’re planning to breed, make sure you have a pair of the same species! See below.
It can be difficult to determine the sex if you don’t have much experience. I can always help if you can send me good pictures of the underside.
What species is my Heterometrus?
Heterometrus species are often sold under the wrong name, because identifying the species can be very hard. Heterometrus sp. can only reliably be identified from around instar 5 and up. The most common Heterometrus species in Europe and North America right now is Heterometrus silenus, previously known as Heterometrus petersii. This species is totally black/dark brown, including the telson (stinger), with little granulation on the pedipalps, and can be most easily distinguished by the granulation pattern on the carapace. On top, it is very smooth, with a patch of granulation on either side of the carapace, under the eyes.
Thanks to @Albireo Wulfbooper for allowing me to use the picture.
If your Heterometrus is not silenus (ex petersii), there is more info on identification in this thread: https://arachnoboards.com/threads/identifying-common-heterometrus-revised.94196/
There has since been a revision of Heterometrinae, so some of the names are not up-to-date, but the identifying features are still relevant.
Is my Heterometrus gravid/pregnant?
It may be. No way to tell from a picture. They are often wild caught, so it could have mated in the wild without the seller knowing. Or it could have eaten a big meal. A good way to see if it is gravid is to shine a flashlight through the side of the scorpion (the greyish membrane). You may be able to see embryos. This only works in a later stage of gestation, so if you don’t see anything, try again in a few months. Heterometrus can be gravid for up to a year.
When you think your Heterometrus might be gravid, it's really important to make sure everything in the enclosure is optimal. Deep, damp substrate that allows burrowing, proper hides, and proper temperatures. A spot where the scorpion can warm up to 27-30 C (80-85 F) is important for gravid females. If the enclosure is suboptimal, there is a higher chance of unsuccessful embryo development and/or issues giving birth. Besides the scorplings, this can be dangerous for the mother as well.
Babies will spend the first part of their lives on the back of their mother. After not too long, they will have their first molt, and when their new exoskeleton has hardened, they climb off mom’s back.
Babies can be left with mom for the first few instars. In the wild, they often live communally, and the mom will kill prey to feed the babies. If you decide to separate the scorplings from mom, it’s best to house them in groups, and feed them prekilled, like their mother would.
Why doesn’t my scorpion want to eat?
Scorpions don’t need to eat regularly, and sometimes they will choose to refuse food for a while. I’ve had one Gigantometrus swammerdami refuse food for a whole year! Despite all parameters (temperature, humidity, appropriate hiding places) being right. That should be the first thing you check. Usually, they won’t go off food for super long, but if they do, check if all parameters are good, keep offering food, but not too regularly to cause stress. You may also want to try feeding prekilled prey items. Some scorpions get easily intimidated by live prey, especially young scorplings/juveniles, since they are used to getting prekilled prey from their mom.
Why was my Heterometrus killed/eaten by its enclosure-mate?
Heterometrus can be very communal, especially when raised together. When they weren’t raised together, there is a chance that they start fighting, with possibly lethal consequences. Also, adults are less tolerant than juveniles, espcially gravid females can be very intolerant. Also when the setup is not ideal and the scorpions have to compete for resources, conflicts may occur.
So although Heterometrus spp. are usually quite communal, there are situations where they aren’t, and there are individuals that are less tolerent than others.
That was all the information I often see beginners struggle with. Thanks for reading and I hope it was helpful!
Basic care:
Heterometrus spp. can be kept really similarly to the Emperor scorpion (Pandinus imperator) for which there already is a caresheet on the forum. There are some other ways of setting up the enclosure, but the enclosure described here is practical and easy: https://arachnoboards.com/threads/basic-emperor-scorpion-p-imperator-care.11336/
You can also set up the enclosure without the gravel layer on the bottom, but make sure that the substrate stays damp enough! I will write about this in more detail in the next paragraph.
Some examples of enclosures for Heterometrus sp.:
A simple enclosure for a small scorpling Heterometrus. Thanks to @Edan bandoot for sharing this picture.
A simple enclosure for a juvenile Heterometrus.
A live planted bioactive enclosure for a large Heterometrus. An enclosure doesn’t have to be live planted to be good though.
1. Common mistakes/issues:
Moisture
I’ve seen a lot of people keeping their Heterometrus too dry. Moisture is one of the most important aspects of keeping Heterometrus species. They come from tropical rainforests in Asia, where they have very regular access to water. This means their transpiration rate (water loss) is much higher than the more arid species. To accomodate for this, the humidity in the enclosure needs to be high, because water will tend to diffuse to areas where there is little water, meaning dry air will essentially suck moisture out of the scorpion. This won’t happen as much with humid air.
Exact humidity numbers aren’t important. All that matters is that the substrate is damp all throughout. This is done by mixing the substrate with water before putting it in the enclosure, and regularly add some more water when you notice it starting to dry out. The most effective is pouring a bit of water directly into the substrate. Substrates tend to look a bit darker when damp, making it easy to see when watering is needed. Of course, you don’t want it dripping wet, just damp. Water from the substrate will then slowly evaporate into the air, making it more humid. The most humid part will usually be under the hides (cork bark, wood, tunnels made by the scorpion itself), because the humid air is trapped there.
To make sure the humid air doesn’t leave the enclosure immediately, and the substrate doesn’t dry out too quickly, it is a good idea to restrict ventilation. A standard exo terra, or an aquarium with a mesh lid, won’t hold humidity very well. If you cover a significant portion of the mesh, the humidity is trapped a lot better.
It is also important to offer a water dish that is always filled, so that the scorpion can have a drink once in a while. If the scorpion spends a lot of time in or around the water dish, the enclosure is likely too dry, or it is too hot. Make sure the scorpion cannot drown in the dish. Especially for younger scorpions, it may be a good idea to add some gravel to the waterdish, preventing drowning. A sponge in the water dish is not a good idea, but because it is still common, I will make this a separate paragraph.
Sponge in waterdish
An issue I see with some beginners, is using a sponge in the water dish. This is often recommended by pet stores, but is a bad idea! Sponges are a really good medium for bacteria to grow on, due to the high surface area caused by the open-cell structure. This means the scorpion has to drink from a bacteria infested sponge. You’re better off taking the sponge out. If you worry about the scorpion drowning, you can add some gravel to the water dish or use a shallower dish. Especially for small individuals.
Temperature
Regarding temperature, I would recommend keeping it between 24-30 C (75-85 F). At night, it is fine to let it drop to around 20 C (70 F). If you keep them cooler, the metabolism of the scorpion will be compromised, meaning it won’t eat and grow much.
If you live in a cooler climate (or in an air-conditioned room), you need heaters to achieve these temperatures. The enclosure can be heated with a heat mat, heat cable or a lamp. Heat mats and heat cables don’t work when there is too much ventilation for the heat to escape, as they heat more slowly. This shouldn’t be an issue, because if you read the moisture paragraph, you know that you don’t want too much ventilation anyway
. Another thing that is important when using heat mats/cables is that you don’t put them on the bottom, but on the side. Since Heterometrus are burrowing scorpions, they will dig deeper when they feel to warm. Heating from the bottom, they cannot escape the heat by burrowing down, as they will only get warmer. Another issue when heating from the bottom, is that the heat can’t escape because of the deep substrate. This might cause burn marks on the surface the tank is placed on, and could even break the glass of the tank. This is why heat mats/cables should be put on the side of the tank. If needed, you can put isulation behind it so that more heat is pushed in the tank. If it gets too hot, use a thermostat.When using a lamp, make sure the wattage is not too high.
The easiest way to measure temperature is with an infrared heat gun. These are also quite accurate. Digital thermometers with a probe are also usually accurate.
Wild caught vs. captive bred
What a lot of people don't realize, is that the vast majority of Heterometrus sp. being offered, are actually imported from the wild. This goes for a lot of other scorpion species as well, more or less depending on where you live. The scorpions were caught by people that will do anything to earn some money, in a country where the average income is generally low. This makes it really cheap to collect them, and ship them in large quantities to mainly Europe and North-America, among other places. The collected scorpions are usually (sub)/adult. There are a few issues associated with wild caught Heterometrus (as is the case with any imported animal).
In between catching them and them arriving at the pet store/seller, little attention is put into the animals. They are kept in large amounts, in small boxes, with probably little water available. When they arrive here, they're stressed and dehydrated. They also may carry parasites. In the wild, parasites are usually not a big issue, but when exposed to stress, their immune system gets compromised and the parasites may grow in population. All this causes animals to die before arriving here. When they do arrive here, they arrive at an importer. Many importers don't put a lot of effort into the animals either. After that, they finally arrive at the pet store/seller. Some sellers provide proper care, many don't. So even after arriving, not all animals will make it. So you have to realize that when you buy an adult Asian forest scorpion from a pet shop or general invertebrate/reptile seller with no specification on where it came from, it's almost certainly an imported individual that must have had a long journey and needs a lot of time and proper care to recover. Speaking from experience, wild caught animals are much less stable and may just crash suddenly. This is the case for many species of animal, and scorpions are no exception. With Heterometrus, this is not only caused by complications due to the transport process, but also due to the fact that it's usually adults being imported, so the age is unknown.
Another important thing to realize with wild caught animals, is the environmental impact. Heterometrus species are so popular, that there are way more animals being taken from the wild than the population can reproduce. Asian forest scorpions have a very long gestation period and they aren't the quickest growers, so at the current rate, there is no time for populations to recover. Some species that used to be popular, like the emperor scorpion (Pandinus imperator) and the flat rock scorpion (Hadogenes troglodytes), are now very rarely imported because the countries of origin put restrictions in place on their export. This is because the effects were starting to become very serious.
Although the scorpions are still being imported and sold for very cheap, and their reproduction takes a lot of time, which makes it a not very attractive breeding project, there are fortunately more and more people breeding Heterometrus species. When young Heterometrus are being offered and the seller specifically states they are captive bred, those animals are the best Heterometrus to buy. These are usually sold by specialized small scale sellers or hobbyist breeders, whereas bigger companies usually have the wild caught adults.
And when you get a bit more experience with Heterometrus, and you're sure what species you have (they're often sold under wrong names), it would be great if you could do your part by breeding them!
I strive to buy all my scorpions captive bred (and I have a lot, so it can be done
) and I recommend everybody to do the same.2. Common questions:
What sex is my Heterometrus?
Heterometrus species can be sexed by looking at the underside. Here you have the pectines (2 elongated structures with “teeth”) and the genital operculum (the little plate above where the pectines connect).
In females, the genital operculum points more to the rear end of the scorpion, creating kind of a heart shape. The pectines and pectine teeth are usually smaller.
In males, the genetal operculum points more towards the front end of the scorpion, creating kind of a spear shape. The pectines are often longer with bigger teeth.
With some Heterometrus species, the chela (pincher) shape is different between sexes, but this is not the case for all Heterometrus. With Heterometrus silenus, the most common species, there will be little to no difference in chela shape.
If you’re planning to breed, make sure you have a pair of the same species! See below.
It can be difficult to determine the sex if you don’t have much experience. I can always help if you can send me good pictures of the underside.
What species is my Heterometrus?
Heterometrus species are often sold under the wrong name, because identifying the species can be very hard. Heterometrus sp. can only reliably be identified from around instar 5 and up. The most common Heterometrus species in Europe and North America right now is Heterometrus silenus, previously known as Heterometrus petersii. This species is totally black/dark brown, including the telson (stinger), with little granulation on the pedipalps, and can be most easily distinguished by the granulation pattern on the carapace. On top, it is very smooth, with a patch of granulation on either side of the carapace, under the eyes.
Thanks to @Albireo Wulfbooper for allowing me to use the picture.
If your Heterometrus is not silenus (ex petersii), there is more info on identification in this thread: https://arachnoboards.com/threads/identifying-common-heterometrus-revised.94196/
There has since been a revision of Heterometrinae, so some of the names are not up-to-date, but the identifying features are still relevant.
Is my Heterometrus gravid/pregnant?
It may be. No way to tell from a picture. They are often wild caught, so it could have mated in the wild without the seller knowing. Or it could have eaten a big meal. A good way to see if it is gravid is to shine a flashlight through the side of the scorpion (the greyish membrane). You may be able to see embryos. This only works in a later stage of gestation, so if you don’t see anything, try again in a few months. Heterometrus can be gravid for up to a year.
When you think your Heterometrus might be gravid, it's really important to make sure everything in the enclosure is optimal. Deep, damp substrate that allows burrowing, proper hides, and proper temperatures. A spot where the scorpion can warm up to 27-30 C (80-85 F) is important for gravid females. If the enclosure is suboptimal, there is a higher chance of unsuccessful embryo development and/or issues giving birth. Besides the scorplings, this can be dangerous for the mother as well.
Babies will spend the first part of their lives on the back of their mother. After not too long, they will have their first molt, and when their new exoskeleton has hardened, they climb off mom’s back.
Babies can be left with mom for the first few instars. In the wild, they often live communally, and the mom will kill prey to feed the babies. If you decide to separate the scorplings from mom, it’s best to house them in groups, and feed them prekilled, like their mother would.
Why doesn’t my scorpion want to eat?
Scorpions don’t need to eat regularly, and sometimes they will choose to refuse food for a while. I’ve had one Gigantometrus swammerdami refuse food for a whole year! Despite all parameters (temperature, humidity, appropriate hiding places) being right. That should be the first thing you check. Usually, they won’t go off food for super long, but if they do, check if all parameters are good, keep offering food, but not too regularly to cause stress. You may also want to try feeding prekilled prey items. Some scorpions get easily intimidated by live prey, especially young scorplings/juveniles, since they are used to getting prekilled prey from their mom.
Why was my Heterometrus killed/eaten by its enclosure-mate?
Heterometrus can be very communal, especially when raised together. When they weren’t raised together, there is a chance that they start fighting, with possibly lethal consequences. Also, adults are less tolerant than juveniles, espcially gravid females can be very intolerant. Also when the setup is not ideal and the scorpions have to compete for resources, conflicts may occur.
So although Heterometrus spp. are usually quite communal, there are situations where they aren’t, and there are individuals that are less tolerent than others.
That was all the information I often see beginners struggle with. Thanks for reading and I hope it was helpful!
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