The Brown Recluse Spider
March 8, 2023
Some people absolutely love spiders. I am not one of those people, and chances are, neither are you! Arachnophobia is a reality for many people, even though most spiders are completely harmless to humans, and actually prey on important nuisance insects and vectors such as flies and mosquitoes. In fact, there is at least one species of jumping spider which preys primarily on mosquitoes! Talk about a spider you’d like to have hanging around… just not in your house!
Most spiders have no desire to be indoors long-term and only inadvertently enter for food or temporary shelter from the elements. However, some spiders love to be indoors and will adequately reproduce in large numbers if left untreated. Among those are the cellar spider, the American house spider and today’s topic, Loxosceles reclusa or, the brown recluse (or as many might call it, the violin spider or the fiddle spider)!
Brown Recluse Spider Distribution
Brown recluse spiders are found distributed throughout Kentucky and much of the Midwestern and Southwestern United States. In Kentucky, the western part of the state tends to have a higher density than the central and eastern portions. As the map shows, the central and eastern portions have a lighter density than the western portion of the state. Of course, this map only gives us an approximate view of density levels.
The further West one travels into the brown recluse spider’s native zone, the denser the populations can become.
Although Brown Recluse can be found outside its native range, infestations are much more likely to be caused by introduction.
In the mid-section of the state, we still see heavy infestations locally. The difference tends to be that the infestations in central Kentucky are more often introduced, whereas in western Kentucky, infestations seem to be native. While this may seem immaterial, it certainly makes a difference when control measures are being implemented.
Outside of their native areas, brown recluse are much more rare. Transportation is often the source of infestation in such areas. In our experience, they are most commonly transported to non-native areas in boxes, furniture and other stored items. Typically, transported populations are not very successful, although not impossible.
Brown Recluse Threat to Humans
While not known as a deadly spider, the brown recluse, is certainly one of concern. Although a bite from this spider is rare, it can be potentially venomous and pose a serious health risk. It is a good idea for you to become familiar with the spider, as familiarity can help reduce accidental interactions, stop many false sightings and reports and potentially aid in proper medical treatment of bites and misdiagnosed bites. Brown recluse spider sightings are probably reported 10 – 100 times more often than they are actually seen. This can lead to improper treatment by homeowners or expensive calls for pest control when it wasn’t actually necessary. Of course, a licensed and trusted pest control company should certainly be consulted when you are unsure.
Like most spiders, the brown recluse is non-aggressive. I have personally known dozens of people who have lived with a brown recluse infestation for 20 or more years and either never had a bite or never had a venomous bite. Some of these situations contained dense populations of brown recluse throughout the living quarters, to the extent that daily sightings were common. Inspections revealed such numbers that it was almost unbelievable to hear no reports of venomous bites.
Brown Recluse Spider Bites and Skin Necrosis
The biggest threat to you and I, is skin and tissue necrosis from their bite. While brown recluse aren’t actively seeking out a human to bite, it does occasionally occur. This happens when humans inadvertently press against the spider with their bare skin and they bite as an act of self-defense. For instance, putting on a pair of gloves, shoes, or other clothing articles where a spider has made its way inside. Another common bite scenario is when a pile of clothes laying on the floor is picked up or sorted through. Likewise, sorting through other stored items poses the same threat. A good way to prevent bites when sorting through stored items is to wear gloves. The fangs of the brown recluse are too small to bite through clothing.
It has been suggested that 1 in 10 bites are likely venomous and 1 in 100 actually cause serious problems. Most bites, however, either show little to no signs of necrosis or otherwise heal within about 3 weeks. If you think you have been bitten by a brown recluse, it is wise to seek medical assistance before the bite becomes necrotic or infected. Children, the elderly and the infirm are at the greatest risk for serious complications. In this case, do not wait. Take such a person to receive medical assistance immediately.
Sometimes there is no initial pain with a brown recluse spider bite.
While most people who are bitten report little to no initial pain, some bites may cause immediate reactions such as vomiting, fever, chills, rash and possible dizziness. However, it’s the latter results of the bite which can be quite painful. If a venomous bite is left unattended, there can be significant tissue damage. Sometimes, even medical assistance is no match for a venomous bite and may only reduce the effects rather than completely stop them.
A necrotic, dry, sunken patch with irregular red edges and a pale center, and a possible blister towards the center, indicate a venomous bite. This lesion will expand as the venom destroys skin and tissue, often reaching up to several inches in just a few days to a few weeks. The lesion may continue for up to several months and cause a deep and lasting scar. In some cases, the scar may become aggravated years later (as has been noted by several bite victims whom I know personally).
The Brown Recluse Spider Bite Misdiagnosis Saga
It has been my unfortunate experience to find that many spider bites may be misdiagnosed as brown recluse bites. In more than a few occasions, I have been called to the scene of a possible brown recluse infestation, only to find that there are no brown recluse and the customer was bitten by a non-venomous spider. Doctors are not magicians, and neither are they able to see what spider bit you unless they have that specimen. Thankfully, misdiagnosing a spider bite in this case, is no problem at all. Instead, it is a great precaution. However, it is certainly aggravating to deal with a customer whose bite has been misdiagnosed.
Experience with a Case of Misdiagnosis
We were called to a home we regularly service in just such a case. Upon arrival, we began the inspection. After a few hours of thorough inspection, it was determined that no brown recluse were present. So we began to ask a series of questions. Was the bite painful? Where was the customer bitten? What were they doing when bitten? Did the bite make them ill and cause lasting pain? And several more were asked. After a little investigation, we were able to determine that the customer had instead been bitten by a black widow while gardening in the landscape around the home. This caused a minor disagreement as the customer’s doctor was also a trusted friend to the customer. It took several weeks for the customer to finally realize that our diagnosis was indeed correct. At that time, we were permitted to begin treatment against black widows.
Misdiagnosis With No Bite Present
In cases of misdiagnosis, it is important to note that not all doctors have seen a brown recluse or a brown recluse bite and without the offending specimen, it is only a guessing game. Assuming a brown recluse bite and treating accordingly, is probably the safest scenario and is precisely what I would want from my doctor should I think I was bitten by a brown recluse.
Unfortunately, misdiagnosis does not only occur when patients report an insect bite. In many cases, other medical conditions are assumed to be brown recluse bites. In these cases, misdiagnosis could be potentially dangerous. Unrelated lesions due to gangrene, staph infection and other sores are just a few of the misdiagnosed cases I have seen. In cases where no spider bite is reported, but brown recluse-like lesions are present, doctors and their patients should order a thorough inspection to rule out the possibility of a bite. If the patient lives outside the native area for brown recluse, a bite is then highly unlikely. As I stated previously, being informed about the brown recluse can be helpful in several ways, including medical diagnosis.
Brown Recluse Anatomy and Distinction
The brown recluse is often reported at an average size of a US quarter, when legs are fully extended. In my two-and-a-half decades of pest control service, I have seen adults range in size from a quarter to a half-dollar. We have trapped thousands of adults well above the “common” size. However, the average size is in fact, just over the size of a US quarter. Instar sizes vary dramatically throughout the molting process and are less commonly found live or trapped on sticky traps.
In only a handful of cases, we have seen nymphal stages of the brown recluse in large numbers, under the size of a standard shirt button. In the pre-adult stages, certain characteristics of the brown recluse are much less noticeable and in many cases, may be confused with several other small spiders.
Their colors can range from dark brown to a tan color with a slick-appearing, uniform abdomen without striping, banding or mottling. On the cephalothorax is found the most distinguishing feature of the brown recluse; the dark marking which resembles a fiddle or violin. The “neck” of the “fiddle” or “violin” is pointed towards the abdomen and the body of the marking faces towards the head.
This image allows you to clearly see the semi-circle arrangement of the Brown Recluse spider’s eyes
In this image, you can clearly see the most iconic identifying feature of the Brown Recluse Spider; the violin or fiddle shaped marking on the cephalothorax
The spider itself is what we refer to as a “slick” spider, meaning it has little noticeable hair from a distance. They are slender and sleek with long, thin legs which have no noticeable spines or banding.
Many spiders have 8 eyes, but the brown recluse has only 6. These are arranged in a semi-circle in pairs of two. Of course, this is a feature you will not want to be close enough to the spider to see without a controlled environment and a good source of magnification.
Habits and Life Cycle of the Brown Recluse
The brown recluse is a hunting spider and does not build a web to trap its prey. Hunting primarily at night, they will eat both live and dead prey. They are tough spiders and well adapted to both indoor and outdoor living, including with humans. Naturally, they are an outdoor pest first, and are found in their native habitat commonly. Under logs, rocks, piles of wood and debris are all areas where you might locate a brown recluse outside.
In this image you can clearly see the irregular shape of the Brown Recluse webbing. This image was taken inside of a football concession stand in Danville, KY. It is these types of situations that can become dangerous.
Brown recluse are primarily nocturnal and are most commonly confined to dark areas. During the day, they will rarely be seen out in the open. The female rarely move far from her harborage area, which she will line with an irregular web for her egg sacs. Males tend to be more the traveler and are most likely seen rather than a female. When any brown recluse are seen during the day, it is likely indicative of dense and overcrowded infestations, hunger or un-targeted pesticide applications.
In this image, brown recluse spiders are seen nesting on pieces of wood within a wood pile. Such situations can become dangerous when someone begins moving the pieces of wood. Wearing gloves can certainly reduce inadvertent interaction.
Cluttered Conditions Aid Infestations
Infestations can rise to high populations when cluttered conditions are present. Females can lay approximately 40-50 eggs within each egg sac. At only around 1/3 of an inch in diameter, her silk, off-white egg sacs are easily hidden between closely fitted items. She will produce around five egg sacs in her life span of 2 – 4 years. Within the egg sacs, the eggs hatch and spiderlings emerge and begin to explore the sac. Soon, they will molt and leave the nest. Over the next year, they will molt between 5 and 8 times before reaching adulthood, leaving behind their shed skins with distinctive stretched-out appearance, as proof of their presence.
Brown Recluse… The Hiding Spider
Inside, there are more places for them to hide than can be listed here! From the hot and dry attic to the cold and wet basement, a brown recluse will hide, live and multiply successfully. If you see suspended webs, however, it’s no brown recluse! Many spiders deploy webs to both live, trap prey and move about. The brown recluse does not.
Cellar spiders, the American house spider, wolf spiders and woodlouse spiders are all spiders commonly confused with the brown recluse. Interestingly, none of them even resemble the brown recluse. These will often be seen in corners of ceilings, doors and floors, right out in the open. The brown recluse’s very name is indicative of their featured habit; HIDING! Brown recluse are, well, recluse! They love to stay hidden and unseen. In many, many cases, large infestations go nearly unnoticed unless a bite occurs.
Cracks, Crevices and Voids
The Brown recluse loves to hide in cracks, crevices and voids. Corners, wall-to-ceiling joints, floor-to-ceiling joints, behind and under trim work, inside cabinets and drawers, between stack items like cardboard and wood, are just a few loved hiding places. Voids in block walls and other walls, drop-ceiling voids, within duct work, and any other voids can provide great breeding and feeding grounds. Attics, crawlspaces, basements, garages and outbuildings can all provide harborage. If it’s cluttered… it’s even the more perfect home for a brown recluse. Stored items including boxed items, clothing, stacked items shoes, gloves and hats are great places to find a brown recluse. Behind and under furniture and beds can provide an equally safe harborage area.
In Detached Structures
Brown recluse infestations occur equally as often within separate structures from the house. Detached garages, barns, storage sheds, commercial building and even boats, plains, trains and cars, can all provide ample harborage. In a nutshell, it’s easy to determine where you might find a brown recluse; if two things touch, a brown recluse would like to be between them! As funny as it may sound, it’s quite true!
Each of the following pictures represent an area where brown recluse spiders could easily hide. We like to say that if it touches or almost touches, is a void, crack or crevice, is dark or damp, brown recluse will hide there.
Behind a mirror or picture hanging on the wall
Cracks and crevices in trim work
Underneath a baseboard trim
Behind unsealed countertop splashguards
In HVAC return vents and duct work
In, under and around cardboard and other boxes of stored items
Under and between magazines and books
In drawers and other areas where stored items are kept
Preventing the Brown Recluse
While it is not necessarily 100% effective, prevention is a great place to start. In native zones, the brown recluse will behave like any other pest and migrate inside in search of food or shelter. This can be greatly reduced by means of exclusion processes.
Starting with gaps, cracks and crevices, sealants and gaskets can be used to reduce entry points. Around windows, doors and plumbing and utility penetrations are where it is most likely to find gaps and cracks. Log cabins and other wood-sided homes are certain to have a plethora of entry cracks which must be sealed to exclude pests.
Seal-plates and bandboards on homes are easy entry points for pests. Sealant where the seal-plate meets the foundation wall can prevent entry. Likewise, cracks where the concrete floor of a basement meets the concrete foundation wall, can also be sealed to prevent pest entry and harborage. Equally important is to reduce harborage ares by sealing gaps and cracks within the structure.
Reducing debris on the outside of the home is also effective. Wood piles and building materials are not to be excluded from the list of debris. Eaves, soffit, metal roofing trim and the bottom edge of siding are great areas for harborage and entry.
How to Avoid the Brown Recluse Bite
It’s important to note that while brown recluse bites may be rare, it only takes one to cause serious problems. If you know you have an infestation, taking precautions against a bite, might save you a finger or a toe!
There are several precautions which one may take to avoid being bitten by the venomous brown recluse. The first is always exclusion. Excluding the pest from the home reduces and even stops infestation. However, introduction is unaffected by exclusion measures. To combat this, indoor harborage sealants can be made to combat infestation success. This includes sealing any cracks and crevices that can be found.
Clutter Reduction and Sealed Storage Containers
Clutter reduction is a priority when combatting or preventing the brown recluse bite. Reducing unneeded items, stored items and junk can help reduce populations and prevent them as well. Keeping shoes, clothes and gloves off the floor are key in preventing bites. Likewise, wearing gloves when sorting through clutter and stored items can aid in preventing a bite.
Utilizing sealed storage containers for stored items, instead of boxes, is a great idea when combatting the brown recluse as well. This can allow you to access stored items without the fear of a bite.
There is no perfect list of places you might find a brown recluse. However, as previously stated, where two things touch, there is where you can find a brown recluse. Furthermore, where two things almost touch, you can find them there too, especially if it’s dark.
Brown Recluse Control
These may be among the most difficult spiders to completely eliminate, though not necessarily impossible. Because of their reclusive nature and their preferred harborage areas, treatment by untrained persons is often unsuccessful. It is recommended that no self-treatment be performed on brown recluse spiders. Not only are the areas and methods of treatment unfamiliar to the average person, but their health threat alone, should be enough to cause one to reach out to a qualified professional for assistance.
If any self treatment be recommended at all, it would be less about treatment and more about monitoring populations and preventing them in critical areas, like bedrooms. This can be achieved, in part, by the use of glue boards (sticky traps). These can be placed against the wall in sheltered, dark areas like under the bed and behind furniture. The more you place, the more spiders you will catch! Put them everywhere you can (and remember that pets, young children and items which may inadvertently come in contact with them will also stick to them). Unfortunately, glue boards will catch mostly males, leaving the females to continue reproduction.
Trust a Professional Pest Company for Your Brown Recluse Spider Control
Professional use of insecticides and exclusion measures are your best bet. Crack and crevice treatments along with void treatments are crucial. Liquids, aerosols, dusts and even fogs may all be utilized in their proper areas. You should always make sure the specific product being used for treatment includes brown recluse on the label. If you misuse an insecticide, it can lead not only to failed treatment attempts but potential health threats as well. At no time do we recommend DIY using any insecticide methods for brown recluse control. However, if DIY is your only option, hire a professional pest company like Four Seasons Pest Solutions as a consultant for your treatment. While this option still comes with a little cost, it can yield much better and safer DIY results when controlling the brown recluse.
Additionally, we offer a range of brown recluse treatment plans from exclusion programs to complete elimination and prevention programs to long-term reduction plans where elimination is not possible or otherwise unlikely. We have had great success in total elimination within areas outside their native habitat and areas of low density. In areas of high density, long-term control methods have yielded results where monitoring glue board placements yield only 1 – 10 trapped spiders a year after initial treatment implementation.
In conclusion, it is imperative to understand that while brown recluse spiders rarely bite and are nonaggressive, bite do occur and can sometimes mean the loss of a finger or toe or serious life-long scaring. DIY treatments are rarely effective and hiring a reputable pest control company will yield better results in controlling populations. If you must live with an infestation, less clutter means less places to hide, and that means less potential for a bite! Keep you and your family safe and healthy and pest free simply by choosing Four Seasons Pest Solutions!
And remember, it’s okay to live among pests, but you don’t have to live with them!