Brown Recluses

 When I was a kid, I knew nothing about brown recluses.  It's no wonder; this spider wasn't described scientifically until 1940 (meaning NOBODY knew about brown recluses until after that point), and wasn't really studied until the early 1960s.  I was a kid in the 1950s and 60s.  I wonder now how many recluses I saw in the house growing up, not knowing how dangerous they could be. Where were all those horrific brown recluse bites back then?  We've all heard the horror stories about huge rotting wounds from the venom of this shy and unassuming spider.  Were bites prior to the 1960s diagnosed as something else?

Actually, there are a lot of misconceptions about the recluse.  It is one of the two Missouri spiders that can be dangerous to humans, but though it is a very common spider throughout its range, bites are rare.  In fact, according to most authorities, bites are far more rare than most people believe.  The tissue necrosis caused by severe brown recluse bites is similar to that brought on by many other causes, including infections such as MRSA.  Doctors, who are seldom knowledgeable about spiders, often misdiagnose otherwise unexplained wounds as spider bites, especially if the person presenting the symptoms suggests (or swears) they have been bitten by a recluse.  For instance, there has never been a live recluse found in California--it is well outside the range of the brown recluse, although parts of southeastern California do have a related species, the desert recluse.  Yet there are hundreds of reports of brown recluse bites in the most populated parts of California, outside even the desert recluse's range.  Medical authorities now believe nearly all these cases were not spider bites at all.  There have also been a number of bites reported in Maine, which is far north of anywhere brown recluses have been found--it is a southern species with Missouri one of the northernmost states that harbor large numbers of recluses.

There is no doubt, however, that brown recluse bites causing serious tissue damage do occur.  Reactions to recluse bites are dependent upon the amount of venom injected, and the sensitivity of the victim to the venom, with 90% of bites not requiring medical attention.  Many bites cause only a small red mark that quickly disappears, and the vast majority do not cause significant wounds or scarring.  However, a "bad" bite really can be a horror story.  It is seldom painful when it happens, but usually starts with a small, white blister, which becomes a hard bump, then a dry, bluish or purplish lesion surrounded by redness.  From there it can progress to a growing area of dying tissue, causing a deep wound than can become as large as 6 inches across. If a bite is going to cause necrosis, it will turn purple in color within 48 to 96 hours, and then black as the tissue dies, with the necrosis eventually falling away, leaving a deep pit that gradually fills with scar tissue.  According to the NIH, a bite can also cause chills, fever, nausea, sweating, and general discomfort.  There is no antivenom for recluses, and treatment consists of taking care of the wound.  Medical sources advise that if you're bitten by a recluse, wash the bite area with soap and water, then wrap ice in a washcloth and apply it to the bite for 10 minutes, remove for another 10 minutes, and repeat until you can get to an emergency room.  My wife Mary was bitten by one when she put on clothing where it was hiding, and her bite progressed to the hard, white bump stage, but eventually disappeared. It was quite painful for several days, but we did not seek medical attention for it.

Because of the questionable reporting of other infections as brown recluse bites, it is impossible to ascertain just how many people are bitten each year.  But according to the latest information, there have been no fatalities from the effects of brown recluse bites in North America.  So recluses aren't quite as fearsome as the urban legends suggest.  I would bet that nearly every home in the range of the recluse, including Missouri, harbors at least a few recluses.  And they can be incredibly numerous.  In one example, scientists collected 2,055 recluses from a single house in Kansas!  But you seldom see them because they are well-named; they hide during the day.  Recluses are entirely nocturnal.  The females build wispy patches of webbing as part of their home, but do not use the weak webbing to capture prey.  They tend to stay in the vicinity of their lair, but males are entirely roaming hunters.  Recluses seem to really like cardboard, perhaps because it is similar to their habitat in the wild, hidden areas beneath logs and tree bark.  Stacked cardboard boxes in a garage, basement, or attic are great recluse hiding places.  You can also find them behind picture frames on your walls, and if you really want to start having nightmares, try getting up in the middle of the night and switching on the lights in any room of your house; chances are you'll see some recluses on the floor near your baseboards, since they like to hide in the thin crack between the baseboard and the floor during the day, and come out under cover of darkness.  While it's definitely an urban myth that the average person swallows so many spiders in their life while sleeping, recluses do roam around at night, and I've had a few crawl across me while I was in bed.  You will also often find one in your sink or bathtub.  Many people think they must come up out of the drain, but in reality they fall into the sink or tub while roaming at night, and it's too slippery for them to escape.  If you have a noticeable infestation of recluses in your house, it's not a good idea to leave clothing on the floor for a day or more because they find that a very good hiding place.  You should also shake out clothing that has been lying around, or even in your drawers, before donning it; most bites, like Mary's, happen when someone puts on clothing where a recluse is hiding.  Their fangs are not long enough to bite through cloth, but bites occur when the spider is pressed against your skin by the clothing.

Recluses are small to medium size, nondescript brownish spiders; their main identifying feature is the dark violin shape on the top of their carapace (the front part of the body).  This marking is usually quite distinctive, though it requires observing the critter from a fairly close vantage point.  They way they hold their legs is distinctive if you are already used to seeing recluses, but difficult to describe.  They can be various shades of brown but are otherwise unmarked.  They are not obviously hairy, but their abdomen is covered by very fine, short hair that gives it a slightly velvet appearance.  The males are slightly smaller than the females, but with longer legs in relation to their body size.  Spiderlets are like lighter miniature versions of adults.

The female usually mates with one male at a time, and will try to eat him after mating.  She deposits her eggs in a white silk pouch about the size of a dime, usually attached to a vertical surface and surrounded by wisps of webbing.  The exoskeleton of the male she mated with may be stuck to the silk near the pouch.  These exoskeletons also remain after the spiders molt, and you will commonly see them loosely attached to surfaces such as cardboard when there are recluse present, appearing as translucent legs and carapace.

The females often produce more than one egg sack, with 30-100 eggs per pouch.  Some eggs get eaten by spiderlets from previous hatches that remain in the web.  Eggs hatch in about 13 days, and by about 50 days later the young are mature.  Recluses have been known to live up to 894 days, and they can live for over six months without food or water.  They are also somewhat resistant to pesticides.  Commercial pest control measures are seldom really effective at ridding a house of recluses; their chief effect is in removing the insects that the recluses feed upon.  But insecticides may also kill the predators of recluses, such as wolf spiders, so they are questionable as a control measure.  Sticky traps around anywhere recluses can hide can reduce their numbers--and it is often disconcerting to see how many recluses you can catch in a sticky trap!  But the best control measure is simply to declutter your house as much as possible.

Another interesting thing about brown recluses is that if a predator grabs them by the leg, or another spider like a wolf spider bites their leg, they can easily detach themselves from that leg to escape and minimize envenoming.  Unlike some spiders, they cannot regrow a lost leg, but they adapt very easily to losing one, altering their gait to compensate.  They can do just fine with as few as four legs, as long as they have at least one leg left on both sides.

There are several other species of recluses, but they are limited to the Southwest from eastern California (the desert recluse) to south Texas, mostly along the Mexican border.  In addition, a "foreign" species, the Mediterranean recluse, occasionally shows up in various parts of the U.S. by hitchhiking in commercial trade.  It is almost identical in appearance to the brown recluse.  Recluses, because of their propensity for hiding in things like cardboard boxes, are probably transported to parts of the country outside their native range, but there is no evidence of significant breeding populations resulting from these introductions.