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All-Stngs-Con-art - 12/16/07


"All Stings Considered" by THLord Conal Mac Nachtan.


NOTE: See also the files: ticks-art, insect-prtctn-msg, lightning-msg, Pest-Control-art, Black-Death-art, p-medicine-lnks, p-medicine-msg.





This article was submitted to me by the author for inclusion in this set of files, called Stefan's Florilegium.


These files are available on the Internet at: http://www.florilegium.org


Copyright to the contents of this file remains with the author or translator.


While the author will likely give permission for this work to be reprinted in SCA type publications, please check with the author first or check for any permissions granted at the end of this file.


Thank you,

Mark S. Harris...AKA:..Stefan li Rous

stefan at florilegium.org



All Stings Considered

by THLord Conal Mac Nachtan


Of the more than 3,000 kinds of spiders in the United States, only about 60 species have been implicated as causing medically significant bites to people. Many spiders are not capable of breaking the skin with their fangs while other species contain venom that causes no reaction.  Spiders are usually very timid and will only bite in self-defense if mishandled, cornered, or injured. Even when they do bite, spiders do not always inject venom.  The severity of the reaction to a spider bite will differ among individuals, but most spider bites are less painful than a bee sting.


Spider bites are placed into three separate categories; possible, probable, and proven.  A Possible spider bite is one which the physician feels could be a bite by a spider, but lack sufficient clinical or circumstantial evidence to support a firm diagnosis.  A Probable spider bite is one in which the clinical and/or circumstantial evidence support the likelihood of spider bite, but the biting spider was not recovered and positively identified.  A Proven spider bite applies to those cases in which the clinical and circumstantial evidence support the diagnosis of spider bite, and the biting spider was captured and positively identified.

Research has shown that approximately 80% of suspected spider bites are caused by other arthropods, such as insects and ticks, or other disease states.  Conversely, a large number of spider bites are misdiagnosed when first evaluated.  


Most spider bites are single, not in rows or patches like those of some parasitic arthropods (such as bed bugs, biting midges, black flies, fleas and mosquitoes); multiple bites do occasionally occur, such as when the spider is trapped between skin and clothing and cannot escape.  Actual spider bites show two puncture marks although the wound is not always obvious. A rather typical reaction may involve localized reddening and various degrees of swelling, itching, and pain. Within a few hours a small red, blue, or black discoloration can develop around the bite site.  The area may remain tender for a few days, and eventually a small sore can develop that soon begins healing.


Clinically Significant Spiders


Unfortunately, not all spider bites are as mild and fast healing as the typical bite.  There are four types of spiders in the United States that are considered to be clinically significant.  These are the Black Widow, The Brown Recluse (and other Specie of Recluse), several species of the Yellow Sac Spider, and the Hobo Spider.


The major differences in the symptoms and treatment of bites from these spiders deal with the type of venom the spider injects.  Spider venom, like snakebite venom, is generally either neurotoxic or cytotoxic. In spiders it is typically the web dwellers that have neurotoxic venom and the non-web dwellers have the cytotoxic venom.

Neurotoxic venom affects the neuromuscular junctions.  There is usually a sharp, burning pain at the site, spreading to the lymph nodes within 15 minutes.  Severe muscle pain and cramps typically develop within an hour, resulting in tightness in the chest and difficulty in walking. Additional symptoms may include anxiety, raised blood pressure, breathing difficulties and heart palpitations, nausea and vomiting, sweating, excessive salivation and watery eyes.  The body temperature could either fall or rise above normal and the blood pressure may rise with an increased pulse rate.  A rash might develop

The only spiders in the group we are discussing with neurotoxic venom are the Widow spiders of the Latrodectus family, of which three common species (Black Widows) and two lesser known species (Red and Brown Widows) exist in the United States.  Less than 5% of untreated cases result in death, usually as a result of respiratory failure.  Those more severely affected are children (smaller blood volume) and the elderly who might suffer respiratory or heart failure.

Cytotoxic venom affects the cellular tissue and is usually restricted to the area of the bite but can spread.  The bite is at first painless with symptoms developing about 2-8 hours after the bite.   Typical symptoms may include the development of an open ulcerating lesion, with the associated classical "Bulls-eye" pattern within two to three days.  This lesion may take as long as three to six weeks to completely heal.

Of the spiders we are discussing, those with cytotoxic venom include the Recluse family, the Yellow Sac family, and the Hobo Spider.  Bites from these spiders with cytotoxic venom are often referred to as necrotic arachnidism or necrotic evenomation, a term meaning "spider bite which causes tissue death."  Death from a bite of these spiders is extremely rare; only two reports have been documented, both from probable, not proven recluse bites.

Identifying the culprit

It is to our best interest to make ourselves aware of the spiders that may be indigenous to our local area so that we can be aware of the signs and symptoms to look for when a patient may approach us with a suspected or proven spider bite.  Being aware of the spiders' preferred nesting areas and habits will allow us to warn others to their possible presence, and hopefully prevent a bite.

The Widow Spiders  


Photo of western black widow spider,  1996, Darwin K. Vest, Eagle Rock ResearchThe widow spiders, genus Latrodectus, are among the most recognized spiders on earth; they are the largest of the cobweb weavers, family Theridiidae, and all species are venomous.  The term widow spider originated from the idea that the females devour the males after, or during, mating. This mate devouring behavior is somewhat a myth; while it may occur in captive situations, where the male cannot escape, it is uncommon in the field.

Black Widow spiders inhabit most warmer regions of the world to latitudes of about 45 north and south.  They can be found on the underside of rocks and ledges, in plants, debris piles, woodpiles, etc.  Widow spiders build strong, sloppy webs, in which the females usually remain, hanging upside down most of the time. Female widow spiders are bulbous and shiny in appearance, and may have bodies 12-16 mm long. Males are much smaller than the females, with longer legs; they are so different in appearance than females, that they are rarely recognized as widow spiders by the lay person.  Males are not considered a threat to humans, although they do possess venom and can bite.  Juvenile widow spiders are usually light colored, and darken to their adult coloration gradually, with each successive molt of their exoskeleton.

The term black widow refers to those species in the United States, Europe, and some other areas, which are shiny black in appearance. The most well known of the U.S. black widows is the southern widow, Latrodectus mactans, whose Latin name translates "murderous biting robber."  The southern widow is found in the southeastern U.S., west to central Texas and Oklahoma, and north to southern New York; it is also found in the West Indies. Like most widow spiders, it prefers dark, cool places to build its web, such as outhouses, window wells, under well covers, and beneath trash.  The red "hourglass" of the southern widow is actually shaped more like an anvil than a perfect hourglass in most specimens.  The southern widow causes many envenomations in humans, particularly in the southern part of its range, where it is most common.

The western black widow, Latrodectus hesperus (photograph), ranges from extreme southwestern Canada, south into Mexico, and east to west Texas. Hesperus is the common black widow of the western United States, and is abundant in regions of Arizona, California, and other westerly locales. One of its favored natural habitats is in abandoned rodent holes, but it is often found around human habitations, even in the "downtown" districts of many western U.S. cities. The western widows' general appearance is very similar to that of the southern widow; the "hourglass" marking in the western widow is usually shaped like a perfect hourglass, though it is divided into two seperate "spots" in some specimens.  Like its southern cousin, the western widow causes a large number of bites, particularly in the southern part of its range.


The northern widow, Latrodectus variolus, is the third black widow found in the United States. It is found from extreme southeastern Canada, throughout the New England states, and south to northern Florida. It prefers undisturbed wooded areas, stone walls, stumps, and similar habitats. The "hourglass" of the northern widow is usually divided into two separate, elongate markings. This species is most common in the northern part of its range. While its venom is very similar to that of the southern and western widows, and bites do occur, it does not appear to bite humans as often as those species.


The red widow, Latrodectus bishopi, is a U.S. species with a restricted range, being found only in palmetto fronds of sandy, scrub-pine regions of central and southern Florida. This spider is rather brightly colored, with red legs and cephalothorax (fore-part of the body), and a black abdomen with orange and white markings down the back and sides. The "hourglass" usually consists a single red elongate marking. Little is known of the bite of the red widow, but its venom is probably quite toxic to mammals.


The brown widow, Latrodectus geometricus, is a cosmotropical species, found in most tropical seaports around the world; it is an introduced species in Florida. Coloration may vary, but is usually brown to gray, with white and black markings on the back and sides of the dorsal abdomen: The "hourglass" is usually complete. This species is often found on or around human habitations and other buildings. While definitely venomous to humans, bites tend to be less severe than those of most other widow spiders.

The Recluse Spiders


Spider no bigger than a quarterOf the spiders listed, the Brown Recluse or Loxosceles recluse, is the most commonly known.  The brown recluse spider belongs to the genus Loxosceles, a unique family of arachnids known as the Sicariidae, or six-eyed sicariid spiders.  The sicariids have six (rather than the typical eight) eyes, which are arranged in a horseshoe pattern in three clusters of two eyes each.  The family consists not only of the recluse spiders, but also of the six-eyed crab spiders, genus Sicarius, of Central and South America, and South Africa.  

In the United States there are eleven indigenous species of recluse spider, and two species introduced from other countries.  The most noted of these is the brown recluse.  The brown recluse is found in the Midwest and parts of the south; it ranges (see map) from southern Wisconsin east to Ohio, and south to extreme northern Florida and central Texas.  The adult brown recluse has a body length of 10-12 mm (0.4 to 0.5 inches.)  This species is also frequently called the "fiddleback" or "violin" spider, due the violin-like marking on the dorsal cephalothorax.  The apparent presence of a violin-like marking on the cephalothorax or elsewhere is not sufficient to identify a spider as belonging to the recluse group.  Many other spiders have markings which somewhat resemble "violins". The brown recluse became the first U.S. spider associated with necrotic arachnidism in 1957, when it was linked to severe bites in the Midwest.  All recluse spiders, as well as the six-eyed crab spiders, are now considered venomous to humans.

The other ten recluse species which are indigenous to the United States range throughout the lower southwest, from southern California through southern Texas.   Other U.S. indigenous and introduced recluse spiders are:

These other recluse spiders look very much like the brown recluse, and can be positively distinguished only by an expert.  The key in identifying these types of recluse spiders will lie in the geographic area in which the spider is found or the bite occurs.

The Yellow Sac Spiders


The yellow (golden) sac spiders, genus Cheiracanthium are members of the spider family Clubionidae (sac spiders). Members of this family typically build a sack-like, silken tube in foliage or under bark or stones as their lair. There are two species documented to be of clinically significance, Cheiracanthium inclusum and Cheiracanthium mildei.   Yellow Sac spiders can be found walking about on foliage; under leaf litter, stones, and boards; and on buildings under the window sills and siding, in addition to the corners of walls and ceilings within homes.  They probably account for more spider bites than any other spider, and their bites are sometimes misdiagnosed as brown recluse bites by health care providers.   C. inclusum is indigenous to much of the United States (except in the northernmost states), while C. mildei, which is an introduced species from Europe, was found throughout much of the Northeast as of 1978.  It is likely that C. mildei has substantially increased its range since that time. These spiders are relatively small (10 mm body length), and are yellowish to golden in color; they are difficult to distinguish from one another, and positive species identification requires examination by an arachnologist.

The Yellow Sac spider was first identified as a cause of necrotic arachnidism in 1970, when it was linked with skin lesions in the Boston, Massachusetts area (where it is the most common spider found in houses); it is also common in houses in New York City.  In the late 1970's and early 1980's the Yellow Sac spider produced a significant number of bites in the Provo, Utah area, and has been reported responsible for bites in Georgia and southwestern Canada; bites by this species are probably far more common and widespread than this, and it is likely that more reports will surface as the Yellow Sac spider becomes better known as a clinically significant spider.

Yellow sac spiders are among the least known clinically significant spiders, but they are indeed capable of causing a painful bite with development of a necrotic lesion (not as severe as the brown recluse or hobo), and can sometimes produce systemic effects as well.  They are very prone to bite defensively (more so than any other significantly venomous U.S. spider), and some bites in humans have occurred in unusual places, such as in automobiles and swimming pools.  The bite of C. inclusum is more destructive then the bite of C. mildei.  Humans usually incur C. inclusum bites outdoors while gardening in the summer.  C. mildei will readily bite, despite their small size, and they have been observed crawling across the human skin surface and biting without provocation.   It is likely that many U.S. cases of necrotic arachnidism ascribed to the brown recluse spider outside of its natural range are actually Yellow Sac spider bites.

The Hobo Spider


The hobo spider, Tegenaria agrestis, is a moderately large spider of the family Agelenidae which is originally indigenous to Western Europe.  The Hobo spider was most likely introduced into the northwestern United States through the port of Seattle sometime before the 1930's.  They are brown and measure roughly 10-15 mm (0.4 - 0.6 inches) in body length and 15 to 45 mm (0.6 - 1.8 inches) in leg span. Their legs show no distinct rings and have short hairs. Their abdomens have several chevron shaped markings.  Males are distinctively different from females in that they have two large palpi (mouth parts) that look like boxing gloves.  These palpi are often mistaken for fangs or venom sacs, but they are in fact the male genitalia.  The females also have these palpi, but the ends are not enlarged as they are in the males.  Females tend to have a larger and rounder abdomen when compared to males.

The Hobo spider has a distinctive web that is horizontal and flat with a funnel at one end. These funnel shaped webs are often attached to an object in the yard, by the foundation of structures, or anything that remains stationary near the ground. The spiders rarely climb vertical surfaces and are uncommon above basements or ground level.

Ranges of Spiders known to inflict Necrotic Evenomation

Each of the spiders documented to inflict necrotic evenomation, the Recluse spiders, The Yellow Sac spiders, and the Hobo spider, has a specific range in which it lives.  Of these spiders, the Yellow Sac spiders range includes most of North America, and is therefore not define as a subsection of this map.  These ranges are defined by many factors, including, but not limited to the spiders' mobility, the presence of predatory species outside its known range, and its climatic adaptability:

It becomes obvious when looking at the ranges of the various spiders that many of the spider bites reported in the media as having been inflicted by a Brown Recluse occurred well outside the known range of that spider.  While each of the spiders discussed in this article can produce a necrotic lesion as one of its symptoms, the systemic effects of the bites of these various spiders differ, and may be treated in different ways.  Knowledge of the ranges of these spiders can help prevent the misdiagnoses of the type of bite, and can be essential in helping the victim of a spider bite receive the best possible care.

Signs and Symptoms


Spider venom poisoning is characterized by a set of signs (observable physical or objective evidence of disease) and symptoms (complaints that the bite victim relays to the physician, etc.), which lead to the diagnosis of spider envenomation.

When envenomation does occur from the bite of a spider, local and/or systemic manifestations may appear. The severity of these phenomena is dependent on the type of spider, and in the case of the hobo spider, on the age and sex of the biting spider.  For example, in laboratory experiments the venom of the male hobo spider produces more severe effects than that of the female, and evidence exists suggesting that the venom of sub-adults may be more toxic than that of adults.

Bites by widow spiders often are initially painful, but sometimes are not felt.  The local dermal reaction is minimal, usually consisting of little more than an area of erythema (redness) around the bite site, which disappears within several hours; no tissue necrosis occurs following bites by widow spiders. A potent neurotoxin in the venom induces the disease state latrodectism, which manifests itself with severe muscle cramping and spasms; the cramping usually begins in the large muscle masses of the legs, or the abdomen.  The abdomen can exhibit a board-like rigidity, and the pain has been compared to that of acute appendicitis, and to childbirth.  Some widow bite victims experience anxiety, profuse sweating, nausea, piloerection (hair standing on end), increased blood pressure, and other unpleasant manifestations.  Paralysis, stupor and convulsions, as well as psychological abnormalities may occur in severe cases. Death can occur in a small percentage of cases, particularly when the victim is a small child or elderly person.

In envenomation by Hobo and Recluse spiders, a large (several cm.) area of redness (erythema) forms around the bite site: This usually disappears within a few hours, leaving a small reddish induration (hardened area), which is not dissimilar to the classical "mosquito bite". Within 24 to 48 hours blistering may occur at the bite site.  Within an additional 24 hours these blisters may rupture, leaving an open ulceration.  Within a few days of ulceration, if left uncovered, eschar or "scab" formation begins to develop over the lesion, and by three weeks post-bite this becomes pronounced, giving the lesion a "target and bulls-eye" appearance.  Following this, the "scab" is sloughed and the lesion generally heals, leaving a scar, within 45 days of the original bite.  In some instances, particularly when the bite is delivered in an area of fatty tissue, such local lesions may become deep and extensive, and may not heal for two to three years.

Systemic or generalized effects are referred to as the disease state tegenarism and are seen in about 45% of persons envenomated by Hobo spiders. The most common reported symptom is severe headache, which usually does not respond to over the counter analgesics (aspirin, which can prolong bleeding time, should not be used for hobo spider bite induced headaches.)  In addition to this, victims may experience a dry mouth, nausea, weakness and lethargy, dizziness, visual disturbances, hallucinations, joint pain and/or other undesirable effects.  As with many types of complex poisoning, most victims of systemic tegenarism do not experience all of these phenomenons, but that is dependent upon the severity of the poisoning.  About 15% of envenomated subjects are poisoned severely enough to require hospitalization.  In rare cases aplastic anemia (bone marrow failure) can develop several weeks after the bite, which results in a fatal outcome.  Another rare but dangerous condition that has been seen following hobo spider envenomation is the development of severe intractable vomiting accompanied by secretory diarrhea.

The systemic effects of brown recluse spider bite (which occur in a small percentage of cases) are referred to as the disease state loxoscelism and differ somewhat from those of the hobo; chills, fever, nausea, muscle pain, and other flu-like symptoms can develop. In severe cases convulsions may occur, as well as abnormalities in the clotting ability of the blood.  Hemolysis, or damage to red blood cell walls resulting in leakage of the red, oxygen carrying protein hemoglobin occurs in some cases; this can result in the death of the victim when the discarded red blood cell casts are filtered through the kidneys, causing renal failure.  Systemic poisoning effects from the other various members of the genus Loxosceles may vary from species to species.  Little is known about the venom and bite of the lesser known species of recluse spiders.

Bites by Yellow Sac spiders generally produce instant, intense stinging pain, not unlike that of the sting of a wasp or hornet.  This may be followed by localized redness, swelling and itching; these manifestations may or may not evolve into a necrotic lesion, but when that occurs healing is usually complete within eight weeks. Systemic effects are usually not severe, but when they occur may include chills, fever, headache, dizziness, nausea, anorexia, and sometimes shock. Treatment for the local lesion should follow the same protocols as outlined for the hobo and brown recluse spiders.

What to do when someone is bitten


Reassure the Patient:  Most bites initially self identified as "spider bites" eventually turn out to be bites by parasitic arthropods such as bed bugs, biting midges, black flies, fleas and mosquitoes.  These types of bites are typically in patches, rows, or groups. Spiders, on the other hand, tend to bite once, unless trapped by clothing. While a spider bite should not be ruled out based on this, particularly in light of other clinical evidence, informing a patient of this information can help relieve some of the psychological phobias associated with spider bites. Most spider bites are no more painful than a bee sting, and if not accompanied by an allergic reaction to the venom, require little more first aid.

Gather evidence: If possible, if someone is bitten by any spider, and they actually catch the spider in the act, always capture the spider for identification by a qualified arachnologist.  Never discard a spider that has definitely bitten a human.  In the case of the hobo spider, not only is positive species identification important, but so is a determination of the spiders sex and age; these factors can help predict the severity of potential poisoning, and assist the attending physician in charting a course of treatment.  Preserve the spider (or whatever parts of it remain) and send it to the clinic with the patient.


Contacts for the Identification of   Spiders


  Northwestern United States:


ROD CRAWFORD, Curator of Arachnids


Burke Museum


University of Washington


Box 353010


Seattle, WA  98195-3010


Telephone (206)543-9853


E-Mail: tiso   at u.washington.edu


  Arid Southwest (Arizona, New Mexico, NW Texas)




David B. Richman


New Mexico State University


Dept of Entomology, Plant Pathology & Weed   Science


W. 168 Skeen Hall


Las Cruces, NM  88003


Telephone: (505) 646-2900


Fax: (505) 646-8087


E-Mail: nmbugman   at taipan.nmsu.edu




Questions directed to the above individuals should concern spiders and/or spider identification, not questions regarding bites or envenomation.  Spiders submitted for positive identification should always be accompanied with basic collection information, including the date, the exact location (street address, etc.), the name of the collector(s) and any other information about the spider that is available. Do not ship spiders in a simple mailing envelope and do not ship live spiders!  Contact the individual to whom the spider will be shipped for specific instructions.

Provide effective First Aid: For our part, our treatment of any type of spider bite, be it clinically significant or not, will be virtually unchanged.  Typical first aid for a spider bite includes:

Clinically, for most spider bites, no further first aid is typically required.  However, it would be prudent to advise a patient that they should seek medical attention.   If a patient has been bitten by, or thinks that they have been bitten by a spider of clinical significance rapid and proper treatment is essential:  

o      Rest:             Keep the patient or the affected part as motionless as possible.

o      Ice:               Apply crushed ice to the affected area. The cold helps to retard the venom action and reduces pain.  This must be done within minutes of being bitten.  Do not cool for an extended period and remove periodically for the feeling to return otherwise tissue damage might result.

o      Compress:     Apply a compression bandage, winding towards the bite to retard the spread of the venom.

o      Elevate:         Elevate the affected area.  

Calming and reassuring the patient is an important part of initial and continuing care. Some important information that can be conveyed to a patient includes the following:

       Necrotic arachnidism does not invariably develop following a bite by a Recluse, Hobo, or Yellow Sac spider. A large percentage (perhaps 50% or more) of defensive bites by spiders are "dry", and no venom is injected when the spider bites.  Spiders, like many other venomous creatures, are more likely to incorporate venom in a food getting bite than in a defensive bite.

       While extremely painful, the bite of one of the Widow spiders is seldom fatal.  While this may not be reassuring to a patient in pain, it can be very reassuring to friends and family.





Copyright 2006, 2007 William J. Knight.  All rights reserved.  Permission is granted to re-publish this article in any official or unofficial publication of the Society for Creative Anachronism provided that the content is not modified, the article is published in its entirety, and proper credit is given.  For all other uses, contact the author at conal at chirurgeonguild.org or by mail at: P.O. Box 339, Los Alamos, NM 87544


If this article is reprinted in a publication, I would appreciate a notice in the publication that you found this article in the Florilegium. I would also appreciate an email to myself, so that I can track which articles are being reprinted. Thanks. -Stefan.


<the end>


Formatting copyright © Mark S. Harris (THLord Stefan li Rous).
All other copyrights are property of the original article and message authors.

Comments to the Editor: stefan at florilegium.org