The Recluse Spider in New Mexico
There have been a number of reported recluse bites in the Sacramento Mountains of late, especially to pets. Even though this area is not the habitat of the brown recluse, members of the recluse family are here. We have gotten together some information on the recluse family of spiders for our readers, and more will follow on our native recluse - the Apache.
The recluse spiders belong to a unique family of that have six (rather than the typical eight) eyes, 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 of Central and South America, and South Africa. Recluse spiders were the first spider group to be recognized as a causative agent of the disease state now known as necrotic arachnidism, and this condition when caused by a recluse spider is properly termed loxoscelism. Loxoscelism was first recognized in 1872 when Chilean physicians linked a peculiar skin lesion known as the "gangrenous spot of Chile" to bites by the Chilean recluse spider. 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.
At least 56 species of recluse spiders have been described, 54 from the Americas, one from the Mediterranean region, and one from South Africa. Many of these species have only recently been recognized, and thus, most people are not familiar with them. In natural habitats recluse spiders live beneath rocks and fallen debris. In areas inhabited by humans, they take up residence inside houses and other buildings, and may be found in attics, barns, cellars and storm shelters. They can often be found hiding in the folds of clothing, shoes, or underneath boxes in storage rooms. Most species have a mild temperment, and bite only when accidentally pressed against skin, but others, such as the Chilean recluse, are less even tempered.
In the United States there are eleven native species of recluse spider, and two species introduced from other countries. The most noted of these is the brown recluse spider, Loxosceles reclusa, the latin name of which translates "slant-legged recluse". The brown recluse is found in the midwest and parts of the south, it from southern Wisconsin east to Ohio, and south to extreme northern Florida and central Texas. The adult brown recluse is 1/4 to 1/2 inches in body length (most adults are about the size of a United States dime to a US quarter with legs extended).
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".
Many publications refer to the violin on the dorsal surface of the cephalothorax as the most important diagnostic feature. Although this marking is fairly consistent in mature brown recluses and Texas recluses, it can vary in intensity and it is very faint to nonexistent in several recluse species found in the southwestern United States. Therefore, checking the eye pattern will eliminate almost all suspect recluse spiders from consideration whereas the presence or absence of the violin marking may lead to misidentifications. In addition, the abdomens of all recluses are covered with fine hairs and are uniformly colored, although the coloration can vary from light tan to dark brown, depending on what they have eaten. There is never a coloration pattern on the abdomen. Finally, the legs are similarly covered with fine hairs whereas many non-recluse spiders have stout spines on their legs.
The other ten recluse species which are indigenous to the United States look very much like the brown recluse and can be positively distinguished only by an expert. Other U.S. indigenous and introduced recluse spiders are:
- The Apache recluse - Ranges from southeastern Arizona, through southern New Mexico, to extreme western Texas.
- The Arizona recluse - Found in central and southern Arizona, and southeastern California.
The Baja recluse - Found in southern California, and northern Baja, Mexico.
- The Big Bend recluse - Western Texas.
- The Chilean recluse - Introduced from South America, colonies exist in southern California. A large (25 mm) spider, with a particularly severe bite.
- The desert recluse - A pale colored species which ranges from south-central to southern California, east to south-central Arizona, and north to southern Nevada and the Saint George, Utah area.
- The Grand Canyon recluse - Grand Canyon area, Arizona.
- Martha's recluse - Southern California.
- The Mediterranean recluse - An introduced species from the Mediterranean region, which has been found in various cities across the U.S. Its bite is not regarded as being as severe as some of the other spiders of this genus.
- Russell's recluse - Found in the Death Valley area of southern California.
- The Texas recluse - Southern Texas.
- The Tucson recluse - The Tucson area of southern Arizona.
The recluse you will most likely find in the Sacramento Mountains is the Apache Recluse, which has similar venom and characteristics to the brown recluse.
Recluse spiders, as their name implies, are reclusive. These nocturnal spiders emerge from their retreats at night and actively hunt down prey or may wait for prey to land in the small area several inches from their retreat.
Although they do not build webs to capture prey, they do use silk to build a retreat in which they hide during the day. As dawn approaches, they may seek shelter in dark places such as clothing or shoes. Also, mature males roam in search of females. It is these two behaviors that can bring them into contact with people.
In nature, recluses are found in cracks and crevices in and under rocks. Recluses have very much benefited from human-altered environments where they are readily found under trash cans, plywood, tarps, or rubber tires, in boxes, etc. They are synanthropic (found in association with humans) and therefore are considered a "house" spider. In fact, in South America the recluse species have common names that translate as "the spider behind the picture" or "the spider in the corner."
Recluse spiders are relatively long lived. Among the various species, they mature after about 1 year and average a 2- to 4-year life span. They are also well known for surviving long periods (6-12 months) without food before perishing.
Recluse spider bites are a serious medical condition. The bite is nonhealing and causes tissue death. Sometimes surgery is necessary. The bite causes only a mild stinging sensation if any at all. Victims often are unaware they have been bitten. Several hours after the bite, the following signs and symptoms begin to result: A small white area appears surrounded by a margin of redness which may produce a mild itching pain; A blister appears surrounded by mild swelling and redness; A "bulls-eye" or "target" lesion develops.
There may be fever, chills, rash, hives, nausea and pain in the joints over the next few days.
The target lesion will enlarge over the next few days to 1/2 to 10 inches in diameter and produces extensive tissue death. Healing often requires a month or longer, and the victim may be left with a deep scar. Prompt medical attention can reduce the extent of ulceration and alleviate other complications that may develop. It should be noted that not all brown recluse bites result in ulcerations or scarring.
There is no anti-venom, although a type of antidote has been developed, it is not widely available and it appears to be most effective before the lesion develops. In some cases, antibiotics and the drug Dapsone may be used successfully to treat the bites without surgery, but these decisions are made after careful diagnosis by a physician. Prompt medical attention is critical to successful chemical or surgical treatment of the bite. In the end, surgery may be necessary to cut out the dead tissue.
In severe cases convulsions may occur, as well as abnormalites 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. Management of the local lesion, and the use of corticosteroids in systemic poisoning, are the key elements in treatment of bites by recluse spiders. Systemic poisoning from the various members of the recluse family may vary from species to species. Little is known about the venom and bite of the lesser known species of recluse spiders.
The most important thing you can do to control recluses, and other spiders, is remove and reduce trash and rubbish from your property, such as woodpiles, boxes, plywood, tires, and trash cans -- especially if they are stored right next to the house. With attached garages, block off house access by sealing cracks around doors and access holes for electrical conduits or plumbing. In the bedroom, move the bed away from the wall and remove any skirts around the bed. This minimizes chances that a spider can crawl onto the bed. In the Midwest, some brown recluse bites occur when a sleeping person rolls over during the night, and the trapped spider bites in self defense. Do not leave clothes and shoes on the floor, or shake them if they are left out. Apparel and equipment that is only occasionally worn (gardening clothes and gloves, boots, baseball mitts, roller skates, etc.) should be stored in tightly closed plastic bags, especially if stored in the garage or other dark storage areas.
Typically, pesticide control of spiders is difficult unless you actually see the spider and are able to spray it. There are various insecticides available in retail outlets labeled for spider control. It is just as easy and much less toxic to crush the spider with a rolled up newspaper or your shoe. You can also remove a spider from your home by placing a jar over it and slipping a piece of paper under the jar that then seals off the opening of the jar when it is lifted up. If you plan to send the spider to an expert for identification, try to keep it in an undamaged condition because a crushed specimen may be difficult to identify.