Mexican Red Knee Tarantula Care Sheet

Mexican Red Knee Tarantula
Brachypelma smithi tarantula

Common name: Mexican Red Knee Tarantula

Scientific name: Brachypelma Smithi


Description: Mexican Red knee Tarantulas (Brachypelma Smithi) are predominantly black and dark brown, with light brown leg hairs and bright reddy orange making up the distinctive 'red knees'. The abdomen is covered in light brown/grey urticating hairs. They are a medium sized terrestrial spider that are currently protected by CITES (Convention on International Trade in Endangered Species) and are classified as an appendix II species.

Size: They can achieve a leg span of up to about 7 inches.

Life span: Ages up to and in excess of 25 years for females are not uncommon, males on the other hand only live for a very short time in comparison, on average about 3 - 6 years.

Origin: Sierra Madre Occidental and Sierra Madre del Sur in Mexico.

Habitat: An enclosure of approximately 3 times the leg span in length, 2 times the leg span in width and height is required to adequately house this particular spider. They are a terrestrial, burrowing species and require deeper substrate rather than height to climb. Do make sure that your lid can be securely attached as they will escape given the chance.

Temperament: Brachpelma Smithi (the Mexican Red Knee) are one of the best tarantulas in the hobby when it comes to temperament, instead of biting they are far more likely to run away and flick urticating hairs from their abdomen. Keep your face well away from these spiders as urticating hairs to the face would not be at all pleasant. They are a docile species but can be a little skittish at times. They are unlikely to bite but do have the ability to if pushed.

Your vivarium should contain:

All that is really needed for this species of spider is a hide and a water bowl. The water bowl needs to be buried so just the rim is above the substrate. They require hides on ground level (buried slightly) and you can use anything at all as a hide really, I would suggest cork bark, coconut halves and plant pots as good and inexpensive hide solutions. Any decoration other than this is up to you, although plastic plants do look nice.

Do not use sponges in your water bowl as they are not needed and are really just a breeding ground for bacteria and other nasty things.


Substrate is very easy to get right for this species, there are however a few options that you can choose from. They like a sandy substrate so a 50 - 50 sand and peat moss substrate can be used (potting soil works just as well as peat moss). Alternatively you can use a 50 - 30 - 20 mix of peat moss/potting soil, sand and bark chips. Coco fibre is also available and can replace the potting soil or peat moss.

The substrates depth should be half of the height of the enclosure to allow for burrowing and to make sure that the spider is not hurt if it does decide to climb.

With all substrates that you use, always make sure that it is additive and chemical free.


Hygrometers are humidity gauges that are useful to monitor the humidity within a Mexican Red Knee enclosureHigh humidity is not needed for this particular species of spider, they will be perfectly happy with a humidity of around 65% -75%, although at no time should the humidity be allowed to drop below about 55%. Just having a water bowl available at all times will go a long way to providing the needed humidity, a light misting of the substrate (or sphagnum moss if you would like to provide it) every so often is all that is really needed other than that. Do make sure that the substrate is only damp, not saturated.

A digital hygrometer is highly recommended to allow for monitoring of the humidity. These are readily available online and from reptile specialist shops.


A temperature of between 24-27°C (75- 80°F) should be maintained at all times. This temperature can be achieved by attaching a heat mat to the outside back wall of your Mexican Red Knee’s enclosure. A thermostat is very highly recommended and since a heat mat should provide sufficient heat to keep your Mexican Red Knee happy, a basic mat stat, like the Microclimate Ministat 100 or the Habistat Mat Stat, should be appropriate. These thermostats are available from reptile shops and online, are relatively cheap, and will ensure the heat source is regulated at a safe level. A thermometer is also recommended.


Brachypelma Smithi are rather unusual when it comes to lighting. Most spiders do not like lots of direct light whereas this species does not mind it and can sometimes be seen basking. For that reason you can, if you wish, provide a basking spot for your Mexican Red Knee just outside of the hide. Just be sure that any lighting you do use does not add too much heat to the enclosure and make sure your lighting is set up so that inside of the hide is still dark. I would say that LED lighting would be ideal, preferably the kind where you can adjust the brightness to suit your Mexican Red Knee. Alternatively a desk lamp can be angled down onto the enclosure but temperatures will need to be closely monitored. Lighting is NOT essential though, so it is really down to personal choice.

General Care


A live invertebrate prey item of approximately half of the spider’s body length is required. You can choose to feed crickets, locusts, mealworms, or even cockroaches. Wingless fruit flies are also a good option for feeding spiderlings. Approximately 4 or 5 food items of an appropriate size should be offered per week, they can be offered all in one go but if they have not been consumed within 24 hours they should be removed and you should try feeding again in a weeks time.


Sexing of a Brachypelma Smithi is really quite a simple process if you have access to a previously shed skin. If you do have access to a shed skin you need to look inside on the abdomen just about where it meets the carapace, if you have a female spider you will see a prominent structure known as the spermathecae which is basically a sperm receptacle. A male spider will clearly not have this present. The spermathecae, or lack of it, is clearly visible to the naked eye if the spider is large enough, although a microscope or strong magnifying glass will be needed for a spiderling.

An easy way of identifying a male tarantula that is living is to again look on the ventral (belly) side of the spider, on the abdomen just about where it meets the carapace there is what is known as the epigastric plates. Next to this, going in the direction of the spinnerets is what is known as the epigastric furrow. On the central anterior side of this furrow you will see an almost arch shaped patch of dark, short, densely packed setae (bristles), these are only found on male spiders and are actually very small spinnerets that are believed to be used when the male makes a sperm web.


To grow, your Mexican Red Knee grows a new skin below its current exoskeleton, when the spider has grown sufficiently it will need to break out of its old exoskeleton. This is called molting. At this time your spider will show less interest in its food and will appear to be being very lazy. You will also probably see your spider laying on its back, it is VERY important that you do not touch your spider when it is laying like this, you also need to remove all uneaten prey items from the enclosure as gently and quietly as you possibly can. The spider will eventually split open its old exoskeleton and wriggle its way out. The spider’s nice new exoskeleton will still be very soft and you will more than likely see it just sitting still as it hardens. Only remove the shed exoskeleton when your spider is again actively walking around its enclosure or has returned to its hide. You should also not offer any food items to your Mexican Red Knee for a week as your spider’s skin and fangs will still be rather soft so it will not be able to eat.


Handling of any tarantula is not without risks, they all have the potential to bite and are all venomous. The strength of the venom is not enough to kill you but is certainly not pleasant. Your spider does not need or want to interact with you and will gladly spend all of its time just going about its business undisturbed. That being said, you can, if you wish, handle your spider. Brachypelma Smithi are usually tolerant of handling but you ignore the warning signs at your own peril.

For starters, if you handle your Mexican Red Knee and are scared or nervous it is very likely to end up with injury to either you or your spider... or both of you!

To handle your spider and to minimise the risks the best way is to have a paint brush or another soft item available to gently push your spider. Now, place your hand palm up so that your spiders head is facing you, if it shows any threatening signs, such as rearing up with its front legs... STOP, the spider clearly does not want to be handled. Next, using the paint brush you need to gently prod the abdomen or rear feet of your Mexican Red Knee, you will either see the spider walk forwards, rear up or spray urticating hairs. If your spider has now walked onto your hand you should lift your hand slowly out of the enclosure and allow the spider to walk from hand to hand. Keep your movements slow and try not to breathe on the spider, this should help to keep your Mexican Red Knee calm and not spook it. Until you grow in confidence it would be advisable to keep your hands close to a table or bed so that if you drop it you will lessen any possible damage caused.

This website will not take any responsibility for injury caused to either you or your Mexican Red Knee, you handle your spider at your own risk.


Female spiders benefit from a cooling period of a few months prior to mating. When your mature male makes a sperm web he is ready to be introduced to the female. He should be placed inside the female’s enclosure, at which time he will slowly walk up to the females hide vibrating his legs and tapping his feet into the ground to lure the female out. When she is out far enough the male will usually lunge onto her and push her into an almost upright position so that he has sufficient access to the female’s epigyne. At this time the male will insert one or the other of his pedipalps into the female’s epigyne to inject his sperm. When the male disengages from the female he should immediately be removed from the female’s enclosure. If the female has been successfully mated she will produce an egg sac over the coming weeks. The egg sacs can contain over 250 babies. After mating the male will usually die within a few weeks.

Any more Questions?

This care sheet is a simple step-by-step guide to successful Tarantula keeping, but if you have anymore questions or need more specific information about the care of your Mexican Red Knee spider, please enter our forum. It is a useful resource where you can ask other members to share good practice and also talk about your experiences of being a Mexican Red Knee keeper.

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