The Brown Recluse Spider…Watch Out!
Three-quarters of the human population is intimidated by spiders in one way or another – and there are about 3,400 species reside in North America alone. Spiders are actually very useful to our gardens and homes. This is particularly true about the nonpoisonous and harmless variety. Spiders aid in controlling the populations of other household pests such as grasshoppers, cockroaches, mosquitoes, and aphids. Often having some spiders in the house is a natural way of dealing with your pest problems, removing the necessity of buying pesticides. Through limiting the populations of other disease carrying pests, spiders may significantly prevent the onset of several diseases otherwise borne by the pests they control.
One spider you do not want to cross is the brown recluse. It looks like a common brown spider, but its bite has often been associated with skin necrosis. Brown recluses love hiding in stacks of wood or cardboard.
It is sometimes referred to as the ‘violin’ or ‘fiddleback’ spider because of the violin-shaped marking on its dorsum. Although brown recluse spider bites are rare, the venom can sometimes cause serious wounds and infestations should be taken seriously.
Basic Facts
The brown recluse spider, initially found throughout the south central and Midwestern United States however most recently, sightings and even fewer infestations have been reported throughout the U.S. Recluse spiders are rarely found outside their native range. In general, these spiders are widely over-reported and less common than perceived. Occasionally, one or a few spiders may be transported to a non-native area in boxes or furnishings, but infestations seldom become established.
Though variable in size, adult brown recluse spiders with legs extended are about the size of a U.S. quarter. Coloration ranges from tan to dark brown, and the abdomen and legs are uniformly- colored with no stripes, bands, or mottling. The legs are long and thin and lack conspicuous spines. For laypersons, the most distinguishing feature of a brown recluse is a dark violin-shaped mark on its back, with the neck of the violin pointing toward the rear (abdomen) of the spider. This feature is consistent in adult brown recluses, but sometimes less obvious in younger spiders.
A more definitive diagnostic feature is the eye pattern — brown recluses have a semi-circular arrangement of six eyes (three groups of two) while most other spiders have 8 eyes. Seeing this feature requires a good quality hand lens and is best left to have a specimen confirmed by an entomologist or our team here at Millette Pest Control.
Habits / Reproduction
In nature, brown recluse spiders live outdoors under rocks, logs, woodpiles, and debris. The spider is also well adapted to living indoors with humans. They are resilient enough to withstand winters in unheated basements and stifling summer temperatures in attics, lasting many months without food or water. The brown recluse hunts at night seeking insect prey, either alive or dead. It does not employ a web to capture food — suspended webs strung along walls, corners, ceilings, outdoor vegetation, and in other exposed areas are almost always associated with other types of spiders. In homes, such webs are often produced by harmless cobweb or cellar spiders. While sometimes considered a nuisance, spiders like the cobweb or cellar varieties prey upon other pests (including brown recluses), and in this sense could be considered beneficial.
During daylight hours, brown recluse spiders typically retreat to dark, secluded areas. They often line their daytime retreats with irregular webbing, which is used to form their egg sacs. Adult female recluses seldom venture far from their retreat, whereas males and older juveniles are more mobile and tend to travel farther. Consequently, they are more likely to wander into shoes, clothing or bedding at night and bite people when they inadvertently become trapped against the skin. At times, brown recluse spiders will be seen during daylight hours crawling on floors, walls, and other exposed surfaces. Such behavior can be triggered by hunger, overcrowding, pesticide application, or other factors.
About 40-50 eggs are contained within 1/3-inch diameter off-white silken egg sacs. The tiny emerging spiders gradually increase in size, molting five to eight times before becoming adults. The molted (shed) skins of the brown recluse have a distinct outstretched appearance and can be useful in confirming infestation.
Brown recluse spiders mature in about a year and have an average lifespan of 2 to 4 years. The females produce up to 5 egg sacs in a lifetime. Infestation levels in homes vary greatly, ranging from one or a few spiders to several hundred.
Bites and Medical Significance
Like other spiders, the brown recluse is not aggressive. It is quite common, in fact, to live in a building that is heavily infested and never be bitten. Most bites occur in response to body pressure, when a spider is inadvertently trapped against bare skin. Some people are bitten when they roll over a brown recluse in bed. Other bites occur while moving stored items or putting on a piece of clothing that a spider has chosen for its daytime retreat. Brown recluse spiders have very small fangs and cannot bite through clothing.
The initial bite is usually painless. Oftentimes the afflicted is unaware until 3 to 8 hours later when the bite site may become red, swollen, and tender. Most brown recluse spider bites remain localized, healing within 3 weeks without serious complication or medical intervention.
In other cases, the victim may develop a necrotic lesion, appearing as a dry, sinking bluish patch with irregular edges, a pale center and peripheral redness. Often there is a central blister. As the venom continues to destroy tissue, the wound may expand up to several inches over a period of days or weeks. The necrotic ulcer can persist for several months, leaving a deep scar.
Infrequently, bites in the early stages produce systemic reactions accompanied by fever, chills, dizziness, rash or vomiting. Severe reactions to the venom are more common in children, the elderly, and patients in poor health. Persons bitten by a brown recluse spider should apply ice, elevate the affected area, and seek medical attention immediately.
Controlling Infestations
Brown recluse spiders are difficult to eradicate, largely because of their secretive habits. Virtually any dark, undisturbed area can serve as harborage, and many such places occur within buildings. Because of this (and the potential health threat), treatment is best performed by professionals, like your local PMPs here at Millette Pest Control.
Hiding Locations
Likely hiding places include crevices, corners, and wall-floor junctures, especially behind clutter and stored items. Reducing clutter affords fewer places for the spiders to hide and can enhance effectiveness of treatments. Brown recluse spiders may also live behind walls and inhabit the voids within concrete block foundations. In infested garages, attics, basements and crawl spaces, the spiders, egg sacs, and distinctive shed skins are often found along joists, sills, and rafters, as well as under rolled insulation. In living areas, they sometimes inhabit crevices behind and beneath beds and furniture, closets, clothing, shoes, and stored items. When sorting through boxes or materials, wear long sleeves and gloves to avoid being bitten. Brown recluse spiders also live above suspended ceilings, behind baseboards and woodwork, and within ducts and registers.
Outdoors the spiders may be found in barns, sheds, woodpiles, and under anything laying on the ground. They also commonly reside behind shutters. Migration indoors can be reduced by moving firewood, building materials, and debris away from foundations. Sealing cracks and holes in a building’s exterior can further help to keep these, and other pests, outdoors. Some of the more common entry points for brown recluse spiders include gaps under doors, vents, and utility penetrations, beneath the bottommost edge of siding, and where eaves and soffits meet the sides of buildings. Outdoor populations of brown recluse spiders are less common in the northern portions of its range.
Once again, if you suspect you may have in your home or surrounding area brown recluse spiders, do not hesitate to have the licensed PMPs here at Millette Pest Control conduct a thorough inspection…they are trained to do this… If found, they will recommend a comprehensive approach that may include physical traps and insecticides, if deemed necessary.
Bite Prevention
If you do have brown recluse spiders in your home and as control measures are being implemented, precautions can be taken to further reduce the chance of being bitten. Beds should be moved away from walls and remove any bed skirts/dust ruffles to break contact with the floor. Shoes and clothing should also be kept off the floor or at least shaken out before wearing. Remove excess clutter and store seldom used items in plastic storage containers. There may be some comfort in knowing that bites are a rare occurrence, even in dwellings where brown recluses are abundant.