How to Care for Mexican Red-Knee Tarantulas as Pets

Mexican redknee tarantula

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The well-known Mexican red-knee tarantulas are actually two different species of spiders that reside in the wild on the Pacific coast of Mexico. The Brachypelma hamorii and the Brachypelma smithi both have vibrant "red knees" that contrast their dark body color, making them easy to distinguish from other types of tarantulas. And while scientists say there are slight differentiating features between the two species—like subtle color and shape nuances—both are referred to as "red knees" in the pet industry and are coveted for their beauty, temperament, and long lifespan. 

Breed Overview

Common Name: Mexican Red-Knee Tarantula

Scientific Names: Brachypelma hamorii or Brachypelma smithi

Adult Size: Mexican red-knee tarantulas can have a leg span of about 5 inches.

Life Expectancy: Females can live up to 20 to 30 years, while males live for about 10 years.

Difficulty of Care: Beginner. The Mexican red-knee tarantula is a docile and slow-moving animal, and you can regularly handle it without stressing it out.

Behavior and Temperament

The Mexican red-knee tarantula is one of the most docile and calm tarantulas in the pet trade, making it ideal for beginner keepers. It is slow-moving and can be handled regularly, often with no stress to the animal. This spider rarely bites. However, like most tarantulas, it will kick out urticating hairs from its abdomen and legs if it thinks it's in danger. This natural defense mechanism is meant to embed into an animal's skin or eyes, causing discomfort and physical irritation. In humans, the poisonous hairs can cause an allergic skin reaction resulting in inflammation, rash, and itching. And while this is nothing to worry about, the reaction can last for several hours or days.


A small 5- to 10-gallon tank is suitable for a Mexican red knee tarantula. As a general rule, the width of the tank should be two to three times wider than the leg span of the spider and only as tall as the spider's leg span if it were standing on end. The enclosure should be escape-proof, preferably with a side opening to prevent the spider from falling each time you need to service its tank (since tarantulas like to hang out on top).

The substrate or bedding should be a mix of peat moss, soil, and vermiculite and should be at least 4 inches thick to allow for burrowing and to dampen any falls. Wood, cork bark, or half of a small clay flower pot can be used for a shelter or hiding spot for the tarantula. And adding a few fake plants also helps mimic its natural environment.

Maintaining a consistent temperature and humidity is an important element of Mexican red-knee tarantula care. The recommended terrarium temperature is around 75 to 80 F and can be achieved by using a heat mat under one portion of the tank. While supplemental heating is recommended for most North American environments, it's also important to give your spider a non-heated area to cool off should the tank get too hot.

Humidity levels should be kept around 60 to 70 percent, which can usually be achieved through evaporation from a water bowl. However, in some climates, misting the tank may be necessary. If you see your spider hovering over its water bowl but not drinking, chances are your environment is too dry. Conversely, if it's continuously hiding out in a corner of the terrarium, it is probably too humid. 

Food and Water

Adult Mexican red-knee tarantulas dine on live crickets and other large insects like locusts and cockroaches. This means that you must also feed and raise insects alongside your spider. Grasshoppers and other large bugs can be collected from your yard for feeding, however, their diet must not include pesticide-laden plants. An occasional pinky mouse or a small lizard may be fed occasionally as a protein boost, but make sure to clean the remains from the tank immediately. Also, remove any uneaten insects, as their presence may stress your pet spider once it's full. Mexican red-knee tarantulas usually eat once or twice a week and may take an annual break when they molt.

A small shallow water dish serves two purposes in the terrarium: First, it's a go-to drinking source; second, the evaporation from the dish helps maintain relative humidity in the tank. Make sure the dish is shallow and change it out daily to maintain a fresh and clean supply of water.

Common Health Problems

Most tarantulas are hardy creatures and rarely fall ill. However, due to their eggshell-like exoskeleton, even a fall from a small height can result in death. For this reason, you should always handle your spider when sitting down, preferably on a carpeted surface.

Red-knee tarantulas can also suffer from dehydration, especially since their humidity needs are higher than other varieties. Good husbandry practices should prevent this, however. So watch your spider closely to make sure it's not exhibiting signs of humidity stress.

As with all tarantulas, the red-knee tarantula will go through an annual molt. During this phase your spider may not eat for days or weeks, it may act lethargic and tired, and it may even roll onto its back with its legs in the air. Don't worry. It's not dead. Just leave your pet be and carefully monitor its transformation. Once the molt is complete, remove the exoskeleton from the habitat and refrain from feeding your spider for three to five days. Also, avoid handling your spider during this time and for many weeks after. Your spider's new skin will be fragile and sensitive.


Before you plan on purchasing a Mexican red-knee tarantula for a pet, be aware of its lifespan. A female pet tarantula is a serious time commitment. Also take care to note that this spider, like most, is poisonous. And while the mild venom of this species is rarely a threat to humans, someone in your household could have an allergic reaction if they happen to get bitten.

Since the Mexican red-knee is a popular breed, sourcing a spider from a pet store or reputable breeder shouldn't be hard to do. Purchasing from a breeder, however, is highly recommended to assure the health of your pet. Breeders take great care of their spiders and practice proper husbandry and socialization techniques, assuring a well-adjusted pet.

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