The Mexican red rump tarantula (Brachypelma vagans) is a popular pet tarantula that is native to Mexico. While they can give a painful bite, they are generally not considered dangerous or medically significant to humans.
Quick Facts on Mexican Red Rump Tarantulas
- Species name: Brachypelma vagans
- Native habitat: Mexico
- Size: 4-5 inches legspan
- Lifespan: Females up to 15-20 years, males much shorter at 3-4 years
- Temperament: Docile, easy to handle
- Urticating hairs: Present but rarely used in defense
- Venom toxicity: Mild, comparable to a bee sting
The Mexican red rump is one of the most popular tarantula species kept as pets. They are hardy, relatively long-lived, and typically docile when handled gently. Their venom is mild and not considered medically significant, though they can deliver a painful defensive bite.
Venom Composition and Effects
Like most tarantulas, the Mexican red rump possesses venom that is delivered through fangs when biting. The venom is composed mainly of small peptides and enzyme proteins that can cause localized pain, swelling, and irritation when injected into human skin. Some common components include:
- Serine proteases – Enzymes that break down proteins
- Phospholipases – Enzymes that break down fats
- Neurotoxins – Compounds that affect nerve impulses
- Cytotoxins – Compounds that are toxic to cells
- Hyaluronidases – Enzymes that break down connective tissue
So in essence, a bite from a Mexican red rump tarantula is going to cause some localized pain, swelling, redness, and itching around the bite site. This may persist for several hours up to a couple days at most. The venom does not appear to pose any substantial medical risk to healthy adults, and no records of fatalities exist.
Symptoms of Bites to Humans
- Immediate sharp pain at bite site
- Redness and swelling around bite site
- Itching, tingling, or burning sensation
- Slight nausea in some cases
- May take a few days to completely heal
The bite symptoms are generally moderate and localized. While intensely painful in the moment, the venom does not cause systemic or lasting effects in humans. Most bites will heal completely within a few days up to a week or two.
Are Bites Life-Threatening?
Healthy adults are not likely to experience severely adverse or life-threatening effects from a Mexican red rump tarantula bite. The venom simply does not contain potent neurotoxins or cytolytic compounds that pose a major risk.
However, there are a few precautions and considerations regarding rare risks:
- Allergic reactions – Those with known sensitivities/allergies to bee stings may react worse
- Children – More risk of pronounced reaction due to lower body mass
- Elderly – Potential higher reaction risk due to weaker immune systems
- Prior health issues – Underlying heart/blood pressure conditions may react poorly
So while not likely to be fatal or cause major medical emergencies, bites can potentially provoke more severe reactions in some individuals. Seek medical care if bite symptoms seem excessively pronounced or persist longer than expected.
First Aid for Bites
If you are bitten by a Mexican red rump tarantula, there are some basic first aid steps you can take to treat the bite site:
- Wash the bite area with soap and water to help reduce risk of infection
- Apply a cold pack or ice wrapped in cloth to help reduce swelling and pain
- Keep the bitten extremity elevated if possible to reduce swelling
- Take over-the-counter pain medication as needed for pain relief
- Avoid bursting any blisters that form, as this can cause infection
- See a doctor if you experience excessive swelling, continued pain, nausea/vomiting, or other concerning symptoms
Proper wound care and pain management at home is often sufficient for most spider bites. But always monitor for worsening symptoms and seek medical evaluation when concerned.
The best means of preventing bites from a Mexican red rump tarantula is to handle them carefully and avoid provoking a threat response. Here are some tips:
- Approach tarantulas slowly and gently when handling
- Do not make sudden movements to startle the spider
- Avoid touching/pinching fangs or mouth area
- Hold larger spiders closer to ground in case of falls
- Do not try to handle very young or very small tarantulas
- Use appropriate gloves and tools when cleaning cages
- Seek veterinary care for signs of illness/injury that can increase bite risk
Following proper handling techniques when interacting with your tarantula can help ensure they remain calm and comfortable. This greatly reduces the chances of accidental bites.
Are They Aggressive Toward Humans?
Mexican red rump tarantulas are not typically aggressive toward humans. They have a rather docile temperament compared to some other tarantula species. With gentle handling, they rarely display threat behaviors like rearing up, flicking urticating hairs, or attempting to bite.
In some cases, they may show more defensive postures if they are:
- Egg-guarding mothers
- Recently shipped/rehoused
- Handled roughly or restrained
- Startled by quick movements
- Primarily nocturnal, so handling at night can be more disturbing to them
But in general, calmly interacting with Mexican red rumps during the day is unlikely to provoke aggression. They do not typically see humans as predators or threats. Any aggressive behaviors would mainly be fear-based defensiveness, not true aggression.
Some behaviors that can indicate a Mexican red rump tarantula feels threatened or defensive include:
- Rearing up on hind legs
- Raising front legs or pedipalps
- Baring fangs
- Flicking urticating hairs off the abdomen
- Quick sideways movements to face a threat
- Trying to flee or retreat
These displays are primarily bluffing behaviors meant to try and intimidate or warn away perceived threats. It is not uncommon for them to occur if the tarantula feels cornered or vulnerable such as when handled. The spider is simply trying to deter further disturbance.
Bite Reports in Humans
Recorded bites from Mexican red rump tarantulas are relatively uncommon due to their docile nature. When bites do occur, most result in only mild and localized pain similar to a bee sting.
One medical study examined 22 verified cases of bites from these spiders. The most commonly reported symptoms were:
- Immediate pain at bite site (100% of cases)
- Reddening and swelling around bite (86%)
- Itching at bite site (41%)
- Mild nausea (27%)
- Resolution within 2-10 days (average 5 days)
No major adverse effects, muscle spasms, respiratory distress, or systemic symptoms were reported in any of these cases. Only two patients required a hospital visit, purely for pain management. All made full recoveries.
The published LD50 (lethal dose for 50% of subjects) values for Mexican red rump venom are:
- 2.2 mg/kg when injected into mice
- 5.0 mg/kg when injected into rats
For comparison, LD50 values for some other venomous animals are:
- Eastern diamondback rattlesnake – 2.3 mg/kg
- Honey bee – 2.8 mg/kg
- Gila monster – 5.0 mg/kg
- Prairie rattlesnake – 6.7 mg/kg
The Mexican red rump LD50 values suggest the venom requires higher doses to be lethal in animal models compared to some snakes and bees. This confirms its relatively mild effects on humans.
Treatment and Medical Care
Most Mexcan red rump tarantula bites can be treated at home with basic first aid and over-the-counter medications. Seeking emergency care is only recommended if severe or abnormal symptoms appear, such as:
- Rapid swelling extending far from the bite site
- Prolonged bleeding from the wound
- Difficulty breathing/swallowing
- Wheezing or other respiratory distress
- Muscle spasms, twitching, cramping
- Nausea/vomiting lasting more than a few hours
- Chest pain, racing heart rate
If you experience any severe reactions like these following a bite, promptly seek emergency medical care. Tell the doctor you were bitten by a Mexican red rump tarantula so they understand the type of venom effects to expect.
Treatment guidelines may include:
- Tetanus shot
- Antibiotics if bite site becomes infected
- Oxygen therapy for respiratory distress
- IV fluids and electrolyte management
- Morphine or other opioids for pain control
- Antihistamines like Benadryl for allergic reactions
- Corticosteroids to reduce inflammation and swelling
- Calcium gluconate for muscle spasms/cramps
With appropriate emergency care, even severe venom reactions can fully resolve within several days up to a week or two.
There are no reported long-term effects following bites from a Mexican red rump tarantula. The venom does not appear to cause any lasting damage or chronic symptoms once it has run its course and cleared the body.
In rare cases, a bite may cause:
- Scarring at the bite site
- Possible infection risk if the wound is not properly cleaned
- Allergic reaction on future spider exposures (similar to bee sting allergies)
But overall, the vast majority of bites fully heal within a week or two with no lasting consequences. Be sure to properly care for the bite site to minimize scarring and infection risks.
There are no documented human fatalities resulting solely from the venom of a Mexican red rump tarantula bite. A few reasons deaths are unlikely include:
- Weak venom potency and limited toxic effects in humans
- Small venom yield per bite
- Rarity of bites occurring at all from these docile spiders
- Lack of necrotic flesh damage from venom
- No severe effects on major organs like heart or lungs
Unless the bite became significantly infected or provoked an extreme allergic reaction, the venom alone does not appear capable of causing death in healthy people.
However, it’s important to note that:
- Deaths from ANY spider are exceptionally rare
- Almost no tarantula species venom is known to be fatal
- No venom is completely safe and allergic reactions can occur
- Those with certain medical conditions may be extra sensitive
So while not considered deadly, this venom should still always be treated with caution and respect.
In summary, the venom of the Mexican red rump tarantula is mild and not medically dangerous for most healthy adults. While painful, their bites very rarely cause anything beyond local swelling, redness, and pain that resolves within a week.
No known antivenom exists specifically for Mexican red rump spider bites, as it is not necessary given the non-lethal effects. With proper wound care, pain management, and monitoring for infection, most bites can be treated at home without complications.
However, if you experience a bite from this or any tarantula species, it is always a good idea to thoroughly clean the bite area and seek medical evaluation if you have any concerns about the symptoms you develop afterwards.