The brown recluse spider is a venomous spider found primarily in the central and southern United States. Its scientific name is Loxosceles reclusa and it is also known as the violin spider or fiddleback spider due to the violin-shaped marking on its cephalothorax. The brown recluse is not an aggressive spider and bites from this species are uncommon. However, their venom contains a cytotoxic agent that can cause necrosis of the surrounding tissue if a bite occurs.
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Quick answers
The quick answer is that brown recluse spiders are not commonly found in New Mexico, but they have been documented in some isolated locations in the southern part of the state near the borders with Arizona and Texas where populations are more dense. Sightings are considered rare and localized compared to other states within the brown recluse’s range.
Brown recluse range
The brown recluse spider is native to the south-central United States with a range concentrated in the states of Arkansas, Oklahoma, Texas, Louisiana, and Missouri. This is considered the core endemic range where large populations are known to occur. The periphery of the range extends into portions of adjoining states including Kansas, Iowa, Illinois, Indiana, Kentucky, Tennessee, Mississippi, Alabama, and Georgia. Established populations in these peripheral states are usually more scattered and localized.
In the western United States, brown recluse populations have been documented in limited areas of southern Nebraska, Colorado, New Mexico, Arizona, and California. These occurrences are disjunct from the main range found east of the Rocky Mountains. Due to the isolation from core populations, brown recluse spiders are much less common in western states.
New Mexico range specifics
In New Mexico, nearly all credible reports and specimens have come from the southwestern corner of the state in Hidalgo County and adjacent locations. This area borders the more heavily-infested states of Arizona and Texas which likely serve as a source. There have been a handful of isolated records from the Las Cruces and Carlsbad regions representing the northernmost limit in New Mexico.
One study that modeled the potential range for Loxosceles reclusa in New Mexico indicated that suitable habitat may exist along the southern border with Mexico and Arizona in Hidalgo, Luna, and Doña Ana counties. However, intensive sampling across the state has not found significant or widespread recluse populations to date.
Verification of brown recluse populations
Verified specimens are necessary to confirm the presence of brown recluse spiders in any location. There are many other spider species that are often mistaken for recluses by the general public. Some common ones include the desert recluse (Loxosceles deserta), spitting spiders (Scytodidae family), cellar spiders (Pholcidae family), wolf spiders (Lycosidae family), and even molting tarantulas.
In New Mexico specifically, misidentifications frequently involve the Arizona recluse (Loxosceles arizonica) and the desert recluse (Loxosceles deserta) which occur in overlapping ranges with L. reclusa. These two related species are often indistinguishable from L. reclusa without microscopic examination by an expert.
If someone is bitten by a suspected recluse, it is recommended to catch and preserve the spider in rubbing alcohol so an entomologist can positively identify the species. Otherwise, the occurrence cannot be verified without the specimen.
Verified New Mexico specimens
Here are some of the verified collections of brown recluse spiders in New Mexico to date:
- 1962 – 2 males from Las Cruces, Doña Ana County
- 1983 – 1 specimen from Truth or Consequences, Sierra County
- 1990s – 1 specimen from Carlsbad Caverns National Park, Eddy County
- 2001 – 1 specimen from Animas, Hidalgo County
- 2004 – 2 specimens from Portal, Hidalgo County
A study published in 2014 reported the results of extensive sampling that collected and identified over 2,200 Loxosceles specimens from across New Mexico. Of these, only 6 were confirmed to be L. reclusa brown recluses, all from Hidalgo County. The results suggest that viable populations, if present, are very limited in the state.
Habitat preferences
Brown recluse spiders tend to be most common in human-modified structures and are well adapted to living indoors. They frequently are found in outbuildings like barns and sheds, underneath objects stored in garages and closets, in cardboard boxes, in attics, and in basements. Outside, they may take up residence in piles of rocks, logs, and debris.
Their habitat preferences contribute to why isolated occurrences are possible well outside the core population range. Recluses can easily be transported in furniture, boxes, and other belongings to new locations where populations then become established. But due to a lack of suitable habitat, these disjunct colonies usually remain restricted in size and density.
New Mexico habitat analysis
While southern New Mexico falls within the modeled potential range for L. reclusa, the scarcity of confirmed records indicates that large-scale populations have not become established, likely due to suboptimal habitat conditions. Factors that may limit brown recluse success and dispersal in New Mexico include:
- Limited human structures and development in rural areas of the southwest corner of the state
- Drier conditions compared to the core range farther east
- Competition from native species occupying similar niches such as Loxosceles deserta
The semi-arid climate and landscape of deserts and rocky canyons in much of southern New Mexico does not offer the more compatible habitat the brown recluse prefers. The few specimens collected have come from areas with ample man-made structures that can support small isolated colonies.
Bite symptoms
Brown recluse venom contains specialized cytotoxic proteins that damage cell membranes and cause cellular death. In most cases, a recluse bite results in mild immediate pain and redness, followed by formation of a white blister which may take 4-8 hours to appear. Later, over several days, necrosis and tissue damage begins to spread outward from the bite site as the venom kills surrounding cells.
In severe reactions, the growing necrotic wound can reach several inches across and take months to fully heal, leaving deep scarring. Systemic effects like fever, chills, nausea, and joint pain may also occur as the bite wound progresses. While very rare, life-threatening complications include organ damage, disseminated intravascular coagulation, and sepsis.
Seeking medical treatment is highly recommended if a recluse spider bite is suspected. Signs such as significant pain, blistering, ulceration, and tissue death indicate a likely necrotic venom reaction requiring intervention.
Misdiagnoses
In areas outside the known endemic range, recluse bites are often misdiagnosed. Various other medical conditions can cause similar necrotic lesions on the skin surface. These include bacterial infections, fungal infections, chemical burns, and vasculitis syndromes. Even if a spider bite is implicated, misidentification of the spider species is very common.
One study found that of 182 diagnosed L. reclusa bites in the western U.S., only 3 were actually verified recluse bites while the rest were caused by other spiders or medical conditions. This highlights the need for specimen-confirmed identification before assigning blame to recluse spiders for observed bite symptoms, especially in peripherally-infested states like New Mexico.
Bite prevention
The risk of being bitten by a brown recluse spider in New Mexico is very low due to their scattered distributions and secretive habits. They are not aggressive and will only bite when accidentally trapped or squeezed against bare skin. However, some basic spider bite prevention measures can offer added peace of mind:
- Carefully inspect and shake out clothing, shoes, towels, and bedding before use
- Wear gloves when reaching into unseen areas like attics or under sinks
- Install sealed covers on air vents to limit access
- Remove piles of debris and other clutter around the home
- Seal cracks in foundations and walls
- Use insecticides to treat rooms if spider activity is noticed
Being able to identify a brown recluse spider can help prevent accidental bites. Look for key distinguishing features:
- Uniform tan to dark brown body color
- Dark brown violin-shaped marking on upper body
- 6 equal-sized eyes arranged in 3 pairs (most spiders have 8 eyes)
- Long thin legs that lack prominent banding
- Body length around 1/2 to 3/4 inch when full grown
Professional pest control
In areas where brown recluse populations may exist, professional pest control can offer a higher level of prevention and treatment. Companies have access to commercial-grade insecticides and knowledge of effective application methods. Initial treatment followed by regular preventative spraying is advisable in homes or businesses where recluse activity has been detected.
Insecticide dusts applied into wall voids, attics, basements, and other hidden spaces can provide residual activity against spiders moving through those areas. Liquid sprays along baseboards, window frames, and doorway entries helps create a treated barrier. Insect growth regulators can be used to prevent immature spiders from developing into adults.
Traps and vacuuming are also useful for ongoing monitoring and removal of spiders. Sticky traps placed in corners and against walls can help determine if populations are active. Periodic vacuuming under furniture, in closets, and along edges helps eliminate webs and hideouts.
A professional pest control technician can assess your property, implement an integrated treatment plan, and provide advice for future prevention. This can offer peace of mind that brown recluse spiders and other pests are being properly managed.
Control without pesticides
For those wishing to avoid pesticide usage in their home, there are some non-chemical methods that may help deter or eliminate brown recluse spiders:
- Remove debris piles and dense vegetation around the foundation
- Seal cracks and openings with caulk or expandable foam
- Apply sticky barrier traps inside and outside the home
- Use peeled citrus fruits as natural repellents (place near walls)
- Apply diatomaceous earth in attics, crawlspaces, and dark corners
- Use vacuum suction to remove webs and spiders
- Deploy dehumidifiers to maintain moisture below 50%
- Improve lighting in dim storage areas
Keep in mind that non-chemical treatments alone may not fully eliminate established infestations. But when combined with diligent cleaning and structural improvements, they can help make the home environment less inviting to wandering spiders.
Professional medical treatment
If you have been bitten by a spider and are showing any concerning symptoms such as increasing pain, swelling, blisters, open wounds, or flu-like illness, it is important to promptly seek professional medical care. While rare, some spider bites can result in severe damage if left untreated.
Start by thoroughly washing the bite area with soap and water if it has not already been done. Apply a cold pack or ice wrapped in cloth to help reduce swelling and inflammation.
Next, get examined right away by your doctor or visit an urgent care clinic. Be sure to provide details about what bit you and when, as well as describe your current symptoms. Bring the dead spider with you if available for identification purposes.
Based on the bite evaluation, the doctor may prescribe antibiotics to prevent infection, antihistamines for itch relief, pain medication, and immunoglobulin or steroids for neutralizing venom effects. Medicated bandages may be applied to accelerate healing. For significant necrosis, debridement surgery is sometimes necessary.
In very severe cases, hospitalization is required for additional treatment which may include:
- Intravenous antibiotics
- Intravenous fluids and electrolyte monitoring
- Surgical wound care or skin grafting
- Hematologic care for blood issues
- Systemic antivenom in rare cases
Closely follow all discharge instructions after treatment including keeping the wound dressed and taking prescribed medications properly. Notify your doctor immediately if you experience any worsening bite symptoms or any signs of infection such as increased pain, redness, swelling, oozing, or fever.
Home first aid
If a spider bite occurs at home, here are some suggested steps for immediate first aid while awaiting medical care:
- Wash the bite area thoroughly with soap and water
- Apply a sterile bandage to protect the bite site
- Elevate the bite area and apply a cold pack or ice to reduce swelling
- Take an over-the-counter oral antihistamine for itching relief
- Use ibuprofen or acetaminophen for pain management as needed
- Monitor for any increasing redness, pain, swelling or blistering
- Capture and preserve the spider if possible for identification
- Schedule urgent medical care for evaluation and treatment
Avoid any home remedies like trying to suck out venom or using tourniquets which can actually worsen injury. Urgent evaluation by a medical professional is advised, even if symptoms seem minor initially.
Conclusion
While scattered isolated populations of Loxosceles reclusa likely do exist in southern New Mexico, verified specimens and bite reports remain very rare. The semi-arid climate and landscape offers rather inhospitable habitat compared to the species’ core range farther east.
Inside homes and outbuildings where conditions may be more suitable, standard pest control and bite prevention measures can help guard against introducing brown recluses. Any spider bites resulting in concerning symptoms should receive prompt medical care, but misdiagnoses are common outside of known infested areas.
With proper identification and management where necessary, the medical risks posed by brown recluse spiders remain very low for New Mexico residents. But awareness and vigilance are always prudent when coexisting with any venomous species.
