Odorous ants

3 mm ant on counter

Last month we started to notice a couple of these small black ants exploring our kitchen countertop in Springfield.  Out in nature at the creek we are very tolerant of even this wildlife but this was too much.  We put a few drops of Terro out where they seemed to come in through a window sill.  After a week of taking it home to feed the family, they disappeared.  We sent some photographs to James Trager who provided us an education.

"Those are "odorous house ants" - Tapinoma sessile (Remember to pronounce every vowel in Latin names. )  A very abundant, ecologically catholic (including a wide variety of things; all-embracing), and widely distributed North American "species".  A recent genetic study indicates it has in fact four different geographical-genetic populations that are likely distinct species, but so nearly identical in appearance and habits that no one has yet discerned how to separate them by eye.

They come into my house around now, too, one of the few native ants that remains abundant post invasion of my yard by the Asian pavement ant - Tetramorium tsushimae. In recent years, a colony has daily occupied my mailbox then retreated to the grass below in the evening, during the time of year when daytime air temperatures are higher than those of the soil below, and vice versa at night. " - James Trager

We too have opened the mailbox to find a huge swarm of T. sessile reading our junk mail.  Nests can contain multiple queens and thousands of workers.  For their tiny size they are very rapid, especially when disturbed.  The "odorous" title comes from a smell released from their abdominal glands which has been likened to that of rotten coconut.

 

 

T. sessile from Antwiki CC

Antwiki.org ("Every Ant Tells a Story - And Scientists Explain Their Stories Here") is always a great place to start finding information on ants.  They have a huge article on our odorous visitor.  Here is the opening chapter.

"This species is extremely adaptable, nesting in a wide range of sites and being found in numerous habitats. Nests in open soil, under stones and logs or in dead wood, under loose bark, in cavities of plants or in plant galls, under leaves and rubbish piles and even bird nests. The site of the nest is changed often. Nests are populous with size varying with age (from 2,000-10,000 workers) and contain multiple queens. Brood is found in nests from April until September. Reproductives are found in nests from May until October, flights occur in June and July. This species forages singly from trails and are active during both day and night. They tend Homoptera and feed on dead insects or the juices of decaying fruits and vegetables. It is strongly attracted to sweet substances. It is a common house-infesting ant. "  Antwiki

This just shows just how adaptable species like odorous ants, wood rats and recluse spiders can be, learning how to live on society if not in it.

Feeding a Brown Recluse

The current social isolation has led people to take up gardening, make home improvements, do more cooking, etc. So naturally naturalist Linda Bower tried raising brown recluse spiders (BR). I had better let Linda explain.

"I have been living with a brown recluse infestation for 21 years. My house was built in the late 1800's, a perfect home full of cracks and crevices for their sheet-type webs and infamously reclusive lifestyle. July and August are the worst. They come out of the cracks when it is hot and dry. They are in my shower, laundry basket, closets, in every corner, behind my coffee maker, and yes, my bed. I hunt them at night with a vacuum cleaner and spotlight. In all that time I had never seen them kill. I just had to film them."

Linda raised one of the recluses, feeding it sawfly larvae (see this blog) which were attacking her silky dogwood. One spider killed three sawfly late instar larvae in quick succession. One of the larvae fought back, but a few quick strikes and it was dead. The second died quickly, too, but didn't fight it. The third is in this video where the spider kept jumping back rather than hang on, watching it ooze away. Spoiler alert - could spoil your dinner. The sawfly larva is harmless so why didn't it hang on for the kill?

One possibility is that it used all its venom on the first two larvae. Another possibility from Chris Barnhart is in a paper from 2008 in the Journal of Arachnology. The author raised and fed BR with prey of different sizes, both live, freshly killed or dead prey up to a month old. The study concluded that they preferred smaller prey that was fresh but will feed as scavengers when necessary.

"Overall, recluses preferred live prey over dead, but their choice was influenced by all three variables. Recluses were more likely to scavenge when presented with large live prey paired with dead prey of equal size than when presented with small live and dead prey. Spiders that had fed recently were more likely to scavenge. Finally, recluses preferred dead prey that were freshly killed or less than 24 hours old to items dead for longer periods." The Journal of Arachnology 36:140–144, 2008
Linda kept seven recluses in an aquarium, and being Linda, she had to go on to get this video of a recluse cannibalizing and of course pooping. She also captured it in this video cleaning its chelicera with the tiny fangs at the tip. These are so small that they can't penetrate any clothing.



Recluse fang - Linda Bower

Missouri is in the highest density region for brown recluses. That and more on identification is in this previous blog and in this Wikipedia entry.

Much more details on anatomy etc. is at Bugsinthenews.

Strange Larvae

For many plants, it's the season to be eaten.  I have been patrolling the shaded Mail Trace road along our bluffs, looking for what is chewing what. This shrub caught my eye with several large branches whose leaves were completely skeletonized.  There were a few remaining leaves that were healthy, but turning them over revealed masses of larvae packed tightly together on the underside, hiding from the midday sun and predators.  Other branches were unaffected and Barb identified it as gray dogwood, Cornus foemina, a common shrub along the lane.

For me, the chase to identify a species is half the fun.  I sent this photograph to INaturalist and its first choice was Macremphytus testaceus, a sawfly.  Googling that mouthful (thank heavens for cut and paste) and Bugguide listed its food source as Cornus sp.  BINGO! 

The first photograph I found of the larva was bright orange with crisp black spots.  It does a Cinderella like costume change from the second instar which is covered in a white waxy covering.  They tend to hide out in the daytime and munch away at night. Here they are in this video when annoyed and escaping.

Last instar - Fyn Kynd CC

Sawfly - Tom Murray CC

Sawflies are actually in the wasp family as we discussed in this blog a few weeks ago. As usual, I checked Bugtracks and as usual Charley Eiseman had a great story which I quote:

"I once tried to raise these larvae, and had them in a Ziploc-type bag by my desk.  One night when sitting at my desk, I noticed some motion across the room out of the corner of my eye.  When I went over to investigate, I discovered that one of the larvae had chewed its way out of the plastic bag and had been trying to bore into the windowsill when it fell into a spider web, from which it was now struggling to free itself.  I later found a small pile of sawdust under a nearby chair, which the larva had evidently tried boring into before heading for the windowsill.  It turns out that Macremphytus species burrow into dead wood to overwinter and pupate."

I am currently raising my specimens in hard plastic containers but checking them regularly.

Linda Bower has filmed an encounter between a last instar M. testaceus larva and a Brown Recluse spider and as you might imagine it doesn't end well for the larva. See her video here.  (Spoiler alert- this could spoil your dinner.)

Twitching Spider Leg

As I was sitting at my desk last week, I saw a little brown spider come out from behind some books.  I suspected the spider was a brown recluse so I used a pencil to pin down its legs while looking for an insect box to put it in.  Two of its legs fell off and started twitching, continuing for over two minutes while I got my camera to take this video.

Few spiders can be identified down to species just by their markings.  Even black widows have several species, separated by the details of their hourglass.  The identification of the brown recluse, aka fiddle spider, is "confirmed" by the fiddle marking on the dorsal thorax above.  At least, that is what we were all taught. 

Burkemuseum.org

The Burke Museum calls this a myth as there are other spiders that can have fiddle shaped markings.  Another myth involves an outbreak of L. reclusa  bites in California as this species only occurs in the south-central United States.  Spider identification can be narrowed down by the eyes.

Spider identification is tricky at best but it usually begins by looking at the arrangement of their eyes and comparing it to this chart.  For those of us non-arachnologists, looking one in the eye involves either a smashed spider or a camera.  In this case it was this postmortem view that put it in the Loxosceles genera, called the brown spiders.  There are eleven species of Loxosceles in the United States, but only  Loxosceles reclusa is reported in Missouri.

Loxosceles

Certain identification down to species requires a detailed examination of an adult spider's genitalia under a microscope.  And even the "fiddle" requires some magnification, something I can't do with a moving spider, so all brown spiders of that certain size are brown recluse until proven otherwise at postmortem. 

Exposed "hip joints"

Back to the twitching leg, this is a common finding when Opiliones (harvestmen) lose a leg and has been reported with Pholcids (cellar spiders).  Both groups have extremely long legs and tiny bodies, meaning that predators are most likely to grab a fragile leg.  Cowles describes this as a "flexible secondary defense." *  The leg kicking around on its own entertains the predator and may actually give it a satisfying treat while the victim makes an escape, similar to the twitching blue tail of a five-lined skink.

Opioliones actually have muscles in the trochanter that contract to prevent bleeding.  "Two pacemaker nerve ganglia within the leg are activated as soon as communication with the central nervous system is severed.  They operate independently, causing the leg to twitch and jerk.  The legs even have their own trachae which supply the disembodied legs with oxygen.  The leg can twitch for up to an hour, as opposed to 40 seconds without oxygen."*

I can't find any information on brown recluse spiders having disconnected twitching legs but I have the video and seeing is usually believing.
=====
* Amazing Arachnids, Jillian Cowles.

Brown Recluse Spiderling

I was recently given a very worn specimen of the spiderlings that are infesting our friend's house.  It measured 1/10th of an inch and had been dead on an alcohol pad for several days.  The parent hasn't been seen and their concern was are these Brown Recluse?  If this was our house on the creek I would say 90% likely but she needed better odds. 

Compare fiddle below

The Brown Recluse (Loxosceles  reclusa) is in the Sicariidae Family.  The genus Loxosceles, known as the Brown Spiders, has 11 species that includes the Brown Recluse.  There are several diagnostic features of this family.  First, the legs and abdomen have a uniform color with no spots or stripes.  Second this family has only 6 eyes, unique among all other spiders which have 8.  These eyes are arranged in a "U" " shaped configuration.

  Clay Nichols CC

The most well known feature of the Recluse is the fiddle on the thorax.  The fiddle is more prominent and the fiddle neck is thinner in most photographs so this bothered me.  There are several possible explanations.

1. This specimen had been dead several days and may have lost some color.
2. It might have been preparing to molt with some separation of its cuticle.

Bugguide.net

The coloration and the arrangement of the 6 eyes puts it in the Loxosceles genus.  According to the Arizona.edu site, only L. reclusa occurs in the Midwest with the remainder isolated along the Mexican border so this is as close to a full ID as I can get.

Long-bodied Cellar Spider

Spreading out on the wall - REK

After years of watching these leggy spiders crawl all over the bathroom in our creek house, I thought it was time to give them their day in the sun.  After all they spend the rest of their lives sequestered in dark, damp places asking for nothing and bothering no one, unless it is a house guest too polite to mention them.  For the most part they just hang on a wall or slowly explore the tile floor, looking for tiny pests that we don't even know exist.

This is the Long-bodied Cellar Spider, Pholcus phalangioides, the most common of the Pholcidae or cellar spiders.  They have a number of common names including daddy long-legs spider, granddaddy long-legs spider, carpenter spider, and vibrating spider. Their bodies are 5-8 mm long, (less than 1/3") and their leg are 8 times longer.

"Daddy Longlegs" Crane Fly- Six legs of an insect  - REK

Crane fly - Limonia - REK

Their "daddy long-legs" name is appropriate but can be confusing.  This common name is also applied to both harvestmen of the Opilione class and to crane flies which are sometimes mistaken for giant mosquitoes.  Crane flies have 6 legs like all insects and wings typical of all the Diptera (true flies).


Long-bodied spiders have three distinct body parts (head, thorax and abdomen) while the Opiliones (harvestmen) have the head and thorax fused into one small part frequently making their bodies appear oval.  Both have eight legs typical of the Arachnids.

Harvestman - REK

Long-bodied Cellar Spider - REK

They originated in the sub-tropics but are now found on every continent, probably traveling along with the commerce of humans.  They do not tolerate cold but have found their niche in warm human habitats.  In their original lands they reproduce annually in the warm season while in our house it is always the season to reproduce and life is good.

Skull shaped head with two sets of three round eyes tightly clustered together - REK

Because of the shape of their thorax they are also commonly called a "skull spider."  Another defining characteristic of various spider species is the placement of their eyes.  In this case there is a set of three round raised eyes clustered on both sides of the head as well as another pair in front.

Female with egg case - Olei CC- Wikimedia

A female produces 20-30 eggs which she will patiently carry around in her pedipalps until the young hatch.  The young will molt six times before they reach maturity

Mother and babies - Luis Fernández García via Wikipedia

Their webs are irregular, messy but very small, tending to cling to a wall or other horizontal surface.  When they perceive a threat they start vibrating on their web, making them harder to see, thus the "vibrating spider" name.

Long-bodied spiders have very weak venom and are barely able to pierce human skin, with only a temporary discomfort.  On the other hand, they are considered beneficial as they are predators of many venomous spiders that are threats to us.  As we see an occasional brown recluse in the nooks and crannies, letting these leggy creatures patrol the house is a small price to pay.
============
Recent studies have shown that this species is wide spread in Europe and North America but can have differences in DNA is small "islands" such as apartment buildings.  In Darwin Comes to Town Martin Schäfer of the University of Bonn studied the cellar spiders (Pholcus phalangioides)in buildings in five European cities.  "He discovered that the spiders living in different rooms within one building jointly form a single gene pool, but that each building is a separate gene pool: the spiders move chambers, but rarely move house." *
==========
* Schilthuizen, Menno. Darwin Comes to Town: How the Urban Jungle Drives Evolution (p. 115). Picador. Kindle Edition. 

Harvestman Mating

Gala Solari Keller sent me this picture of two harvestmen head to head, asking if this was predatory or mating.  A "female harvestman" is a bit of an oxymoron, as would be calling her "daddy longlegs" or "granddaddy longlegs."  For that reason I will refer to them by their order name, Opiliones.  Not only are there female "daddies," some species' females can reproduce by parthenogenesis without male fertilization.  Take that, you sexist naturalists!

Opilione - note combined cephalothorax and abdomen into a single body segment.- Wikimedia

Brown recluse body-
Separate cephalothorax and abdomen

Opiliones (pronounced O-pill-e-on-es )are frequently confused with spiders which are in a separate order, the Araneae.  There are two key characteristics which separate the orders.  Opiliones are easily distinguished by a single globular body segment, unlike the spiders which have their abdomen separated from their cephalothorax by a constriction.  They also have a single pair of eyes versus 3 to 4 pairs in spiders, a distinction almost impossible to make on a living specimen as most of their bodies are tiny, typically less than a quarter of an inch.

There is a common misconception, perpetuated in some web sites, that Opiliones can bite humans or that their venom is more toxic than that of a spider.  They actually don't have venom glands or even suck their food as liquids like a spider does.  They actually take in small pieces of insects, plant material, fungus, or even dung.  These are stalkers, not trappers- they don't make webs and don't even have silk glands.

As slow moving creatures they are vulnerable but have several interesting defenses.  They have scent glands which disuade predators such as ants and even birds.  They may bob up and down when disturbed.  They also will sacrifice a leg (after all they have 8), a practice called autotomy.  Because there is a separate pacemaker in the femur, the leg can twitch for a prolonged period, much like the tail of a skink, distracting the predator while the victim sneaks away. 

A predator is not the only cause of the loss of legs.  This video shows the perils of sex in Opiliones.  Males may fight over the female's charms and use their jaws to amputate a rivals legs.  Notice at each attempted mating the pair are face to face.

Mating - note the red mites, a common problem among Opiloines

The closeup of Gala's original photograph above shows the smaller male, on the left, head to head with the female.  A few mites don't seem to be slowing them up.  Mites are a common problem for them, usually one or two per customer.  The one I photographed on Bull Creek had a major infestation and was moving slowly, not attempting to escape from my camera.  These Erythraeidae mites have larvae which parasitize Opiliones, sucking fluid from their legs.

Now back to the original question - dinner or sex?  It turns out that Opiliones mate face to face as seen in this video and lots of pictures including Gala's.  The male has a penis and mates by direct copulation.  This research paper has more details on the anatomy describing how this occurs and may be more than you  want to know.  The important thing is that they know it.

Finally, Opiliones are frequently gregarious, gathering in large masses.  This video is not for the reader with arachnophobia.

Concise information about harvestmen (and women) is at  David Darling's Encyclopedia of Science.

Black Widow Spider

There is more than one reason to have you wife do the weeding of the garden. In addition to being lazy, I am always looking for interesting creatures, and she has the knack of finding them. Just two days after finding the nursery web spider with its egg sack, she came upon a whole different type of arachnid mother.

Barb lifted a concrete block along the garden fence and found this black widow guarding its egg sac.  It became fairly agitated when I got within an inch or two with my camera for macro pictures, so I switched to video mode seen here.


There are 32 species of widow spiders  in the Latrodectus genus including the three "black widows" in the US, the northern, southern and western.  They are named for the habit of eating their mates, although other female spiders and some female insects have the same heartless habit.

The common black widow we think of is the southern black widow, Latrodectus mactans.  The females are jet black with  the famous bright red hourglass on the abdomen.  The males may brown bands on their legs and red and white body markings.

The female has a much more potent neurotoxic venom than the male, delivered by unusually large venom glands.  Their bite is usually painless with symptoms frequently developing later, a trait reflected in its name, Latrodectus, Greek translated as “biting in secret”.  Less that one percent of bitten humans die, a comforting thought until you read the symptoms.

"This spider's bite is much feared because its venom is reported to be 15 times stronger than a rattlesnake's. In humans, bites produce muscle aches, nausea, and a paralysis of the diaphragm that can make breathing difficult; however, contrary to popular belief, most people who are bitten suffer no serious damage—let alone death. But bites can be fatal—usually to small children, the elderly, or the infirm. Fortunately, fatalities are fairly rare; the spiders are nonaggressive and bite only in self-defense, such as when someone accidentally sits on them."  nationalgeographic.com

 Like other cobweb weaving spiders of the Theridiidae family, they have two rows with four eyes each.  Unlike others in that family, their lateral eyes are "completely separated".  Similar to the identifying scale pattern under the tail of our venomous snakes, this identifying feature is not of much value to amateur naturalists, because if you can seen their eyes, it is probably to late.

Black widows tend to hide during the day, coming out at night or when something vibrates their tangled, three dimensional web.  They frequently hang on to their web upside down as seen in our picture above.

An interesting cousin of the black widow is the brown widow, Latrodectus geometricus which was found in Africa and the US around the same time.  They are a lighter color and have an orange hourglass on their abdomen.  A unique identifying feature is the distinctive egg sac which is covered with little spiky points.

Brown widow egg sac- Wikimedia

There is considerable debate about the toxicity of L. geometricus  venom.  Apparently is tends to remain around the bite rather than spreading, and their venom doses are smaller.

A recent report quoted in Sciencedaily suggest that the brown recluse is outcompeting its black cousin in Southern California.  The first US documentation was in Florida in 1935, and they weren't found in California until 2003.  Now they are much more common, found in areas previously harboring black widows.  This is good news only if you are fated to be bitten by one of the widows.

Addendum- June 29, 2013
The latest black widow we found was carrying an egg sac.  This gave me the opportunity to dissect the sac to see the eggs.  I was surprised to see the eggs roll out freely like a bag of marbles onto the table.  Unfortunately it was the kitchen table.  Note to self: open egg sacs outside.

Black widow egg sac

Eggs in case

David Quammen's essay The Face of a Spider has interesting thoughts on the relative value of a venomous species.  

Copperhead Clusters

Copperheads x 4 -Click to enlarge

I received a call from our good friend Sheila describing an invasion of copperheads around her walk between her front door and her parked car.  She had been forced to kill 14 over three days.  Her neighbor a quarter mile away has killed 12 copperheads in her front yard as well. She shares our love of nature in the wild and called me for absolution of her sin.

She first encountered the copperheads when getting out of her car shortly after dark.  There were four within a circle of her flashlight.  This was on the way to the front door 30 feet away, the path her dog and cat use for their nightly duties.  For this reason she was forced to kill them.  This was the first of several sightings of multiple copperheads in the same area over the next week

The next night she was out watering her trees next to the car when she saw a copperhead 8 feet up in the tree.  It was slowly patrolling the trunk not disturbed by her flashlight beam.  You can see it had no difficulty traveling around the trunk.  She took this movie and these pictures.  She has continued to find copperheads in this 100 foot radius from her front door including another one staring at her from a low branch of her redbud tree.

Sheila's house is up on the ridge above Bull Creek, a pretty spot with a view down a valley out the back and a level front yard with mature trees and mowed grass.  There are several piles of wood and downed branches gathered away from the house which would provide harborage both for snakes and their rodent prey.

A famous gathering of snakes, predominately copperheads, occurred just five miles from us at Pine Ridge Church in 1965, leading to Chadwick becoming the "Copperhead Capitol," the subject of the next blog.

Reports of mid-summer clusters or irruptions of copperheads are not just from Bull Creek.  A mid-summer 2005 gathering of 100 copperheads under a cedar tree in Marion County, Arkansas was investigated by an Arkansas State University zoologist with no apparent cause found.   Recent accounts tell of gatherings occurring in Southwest Missouri and Texas.  In summer of 2011 a man in Georgia reported 30 copperheads in his yard.

Back to Bull Creek
This irruptions would be expected in fall when copperheads gather together for hibernation. I have contacted Dr. Stan Trauth,  Professor of Zoology at Arkansas State University who has been studying this common phenomona of mid-summer copperhead gatherings for years.  He confirms that no one knows the reasons these occur.

As you might guess there is no shortage of theories.  In 1965, the Pine Ridge Church irruption of copperheads was explained as "Imps of Satan, sent by the Devil to disrupt the services of the Lord."*  Another source links the 2005 event in Northwest Arkansas to religious reasons also, as it was near Mount Nebo, and Magazine Mountain "which is the possible resting-place of the Ark of the Covenant."

Copperheads are very heat tolerant and usually forage at night during the summer.  Factors commonly mentioned in reports of mid-summer copperhead clusters are heat and dryness.  These reports are from around human dwellings where watering occurs.  Moisture could serve as a draw for insects and mammals, creating a magnet for copperheads.  Rural dwellings frequently have woodpiles and piles of yard waste and limbs, offering harborage for rodents and copperheads.  Another theory comes from a very detailed scientific website, herpsofarkansas.com.

"Human encounters with this snake become more commonplace during the very hottest part of the summer for two primary reasons. One reason is that this is the mating season and males are moving around much more in search of females. The second reason is that it appears this is a time of year when copperheads become increasingly more active in their pursuit of prey. In fact, they may even congregate in areas where large numbers of cicadas are emerging; even pursuing them into trees! Dusk and dawn seems to be when these snakes are on the move the most."  Article link

July cicada

Sheila's yard of mowed grass and mature native trees is a perfect place for cicadas to live out their larval period. She has been seeing cicada clinging to her tree trunks.  They present a juicy treat for a copperhead, even if it has to climb to find them.

What to do?
Killing a snake would be my last resort unless it is around a dwelling where it is a threat to life and property.  However sometimes there is only one letter difference between "loving" and "living" when it comes to rural living.  We are moving into animals' territories as some of them (deer) are moving into our cities.

There is a gradient in what we can tolerate.  At our house on Bull Creek we catch spiders and move them out side... except for brown recluse which die suddenly as do red wasps.  Wood rats are fine in nature but in the house, not so much.  The risk to me in catching and transporting a copperhead out of my yard far outweighs the benefit to nature.

Prevention is the best answer.  Making your space less hospitable to rodents and other food sources will decrease the likelihood of finding copperheads next year.

• Remove trash, yard waste piles and other harborage
• Keep large firewood piles away from the house
• Avoid leaving potential food sources for rodents such as pet food
• Eliminate standing water around the yard
• Seal crawl spaces and access to outbuildings
• Trap rodents to eliminate a food source
• Trim back tall grass and bushes that could hide snakes

This corner of Missouri and Arkansas seems to be blessed with high numbers of copperheads and Ozark natives have always had a close if not always welcomed relationship with snakes.  Silas Turnbo collected Ozark stories around the turn of the century including many revolving around snakes.  The preeminent historian on Ozark folk lore, Vance Randolph, collected many Ozark superstitions about snakes which I have compiled at this site.

2017 Update:
Quote from John Miller of the Missouri Department of Conservation:
""They eat mostly rodents, but copperheads also love to eat cicadas when they just emerge from the ground," Miller said. "Sometimes a property owner might see several copperheads at one time, but they're there to eat the cicadas, which we like to call the 'M&Ms of the insect world.'"
Now play the video of the copperhead in the tree again and listen to the cicada chorus!  That likely explains at least this cluster.

* See the Pine Ridge Church story on next blog.
Here is a Copperhead Safety lesson.

Note:  If you follow the blog and read the "Tree Frog" entry, click on this to see corrections thanks to Dr. Trauth, an expert on Amphibians and Reptiles of Arkansas.

Arachnophobes, Stop reading Now!

Rambo in the shower- click to enlarge

This is the story of Rambo, our resident Wolf Spider.  A healthy four inch leg span means that he generally shows up before we step on him.  He spent several days in the shower recently, close enough to the outlet handle that we had to reach down slowly to avoid scaring him.
As Joel Vance says in the Missouri Conservationist article Spider! Spider!,

"I also like wolf spiders, gray and ominous. They are predators, stalking and killing other insects, and I like to believe that some of the insects they kill are ones I don't want around, maybe even brown recluses."

When I started the article, we kept Rambo around to hold down brown recluse.  It turns out that there is no evidence to support this.
 

Brown Recluse- click to enlarge

Some sources mention that a small wolf spider can resemble a brown recluse.  A brown recluse is generally less that 3/4 of an inch.  One site suggests that you can tell the difference by the fact that the brown recluse has only 6 eyes.  While true, if you can count the eyes on a spider that small, you are way too close!   Even finding the "fiddle" on the top of the cephalothorax is a challenge if the spider is alive and not in a container.

Missouri Wolf Spider**

If you ever look into Rambo's eyes with a magnifier you can see that he is a soulful spider.  There are 8 eyes, as in the picture, and the upper two large ones showing how sensitive he is.  The two brown hairy structures below are the chelicerae, used for grasping its victims.  These are hollow in spiders and eject venom through the black fangs visible on the inner tips.   
I use the term "he" advisably, as Rambo could be Rambette.  I have never been able to see the palps clearly.  Larger club palps are a male feature, necessary to transfer sperm into the specialized female opening.

Speaking of Rambette, there is interesting research which shows that a female wolf spider (Schizocosa uetzi) can recall information three weeks later.  The males have distinctive patterns on different individuals legs which they wave around to entice females.  Researchers painted different colors on the legs of males and exposed immature females to different color-legged males.  Three weeks later when the females reached ssexual maturity, they selected males of the specific color they had seen three weeks before.  and they tended to eat males of the with the other color legs rather than mate with them. * And you thought your teenage years were dangerous.
Unfortunately there isn't any direct evidence that wolf spiders eat brown recluse but since Rambo spends a lot of time in our bathroom and closets, I am sure that he runs into them frequently.  On the other hand, recent research from the University of Kansas shows that brown recluse spiders prefer dead stuff over killing their own dinner.  Zoogoer*

"New research by Jamel Sandidge, a biologist at the University of Kansas at Lawrence, shows that brown recluse spiders scavenge rather than hunt if given a choice. It's the first time a spider has been shown to prefer scavenging over predation.

There can be as many as 2,000 brown recluse spiders in one house.

Sandidge didn't set out to study the hunting and eating habits of brown recluses—his study was focused on the relative population densities in houses of brown recluses, other spiders, and insects. As the study progressed, however, Sandidge made several unexpected observations about brown recluse behavior. In houses, he saw them eating insects that had obviously been dead for a long time. He also saw them running away from insects. He has even watched a brown recluse remain motionless while a potential prey insect walked over it. In the lab, Sandidge says, "I was feeding them yellow mealworm larvae and the problem was that the mealworms were eating the spiders." Sandidge began killing the worms before putting them in the enclosures with the spiders, and the spiders readily ate them.
Sandidge's curiosity was piqued. He set up new experiments, offering the spiders dead prey and live prey. More than 80 percent of the time, the spiders chose the dead prey. 'Brown recluses are very fragile and very weak,' Sandidge says. They often lose legs or even their lives in encounters with live insects, which may explain why they prefer to avoid them."  from the Smithsonian Zoogoer

If you search"brown recluse" in Google you will get lots of fear mongering sites created by exterminators.  If you see an ad, move on.  Brown recluse bites occur rarely and many "spider bites" are something else.  There is good information at the Wikipedia page or here.
Even if they don't actively eat brown recluse, wolf spiders hunt lots of other insects we don't want in our house.  Rambo (or Rambette for Ann) has a secure future in our creek house.

* These stories and a lot more interesting spider facts are at this highly recommended Smithsonian Zoogoer site.  For instance, did you know that:

• One species of Black and Yellow Garden Spider (Argiope aurantia) dies spontaneously as soon as he inserts his second palp in a female to deliver his sperm, even if he does it mistakenly.  
• A type of jumping spider called Portia is able to learn about its spider prey's preferences.  It plays "music" by setting up vibrations in its spider prey's web.  Trying different "tunes" until it gets a response, it then learns that tune and stays with it until the prey comes toward it.  Portia is also able to strategize, even taking an hour or two to sneak around a tree or object to approach its prey from the back side.  That is a lot of memory time for a spider, (or even an older Master Naturalist.)

** Picture by Dan Johnson
Editors Note:  Sadly, we must report the demise of Rambo, or a wolf spider that looks like him, found dead Monday night in the downstairs bathroom.  There were no signs of trauma (i.e. boot marks or compression injury) and we assume that he died in the line of duty, keeping the shower safe from crickets, beetles and possibly brown recluse.  Thanks for the memories.