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Spiders of Oklahoma: Brown Recluse

August 8, 2013

Brown Recluse, also know as a Fiddle Back

With a wet July behind us, we have been introduced to a very hot and humid August. When this happens it is common for residents to see an increase in insects including spiders, roaches, flies and mosquitoes. Although roaches, flies and mosquitoes are annoying little pests they normally do not cause any medical or health issues for humans. Spiders however, can cause many problems. Especially the poisonous ones.

In Oklahoma, only two spiders, the brown recluse and black widow, are considered dangerous to people. However, tarantulas, jumping spiders, wolf spiders, garden spiders, and numerous other species found in the State are frequently mistaken for venomous spiders. These spiders may be formidable, scary or repulsive to some, but to most people their bite is less harmful than a bee sting.

Folklore would have some believe that all spiders are venomous. The facts are that, except for two very small groups (families), all spiders do possess venom glands which void through small holes near the tips of their fangs. However, most spiders do not bite humans, and with a few exceptions, spider venoms are not harmful to humans or other mammals. Spiders are important predators which help keep insect and some other arthropod pest populations in check. This beneficial role far outweighs the hazard posed by the few spiders that occasionally bite humans.

Some people have a phobia of spiders (arachnophobia). Some of these fears of spiders are because people believe they are aggressive and will attack humans with little or no provocation. Nothing could be further from the truth. Only one spider in the world is considered aggressive—the funnel-web spider of Australia, Atrax robustus, which reputedly will attack without provocation. No other spider is overly aggressive unless cornered, injured, or otherwise overly provoked. It is true that many North American spiders will rush over their webs to investigate any disturbance. This is a natural hunting reaction, as many species of spiders employ webs to entrap other animals for food.

It is a false impression that the bites of known dangerous spiders always cause a very serious condition or even death. The truth is that fatalities from spider bites are rare, and the consequences of the bite may range from trivial to severe. The severity of the reaction to spider venom is dictated by many factors. The amount of venom injected may vary from almost none to a full dose, depending on the site of the bite, the length of time the fangs are in the tissues, and the quantity of venom injected. Also, the reaction of different individuals to the same type and amount of venom may vary widely, since age, general state of the victim’s health, and differences in genetics would likely determine the severity of reaction.

We will be covering several of the spiders that make their homes in Oklahoma, along with providing a photo to help you identify your creepy crawly.

The first spider we will be taking a closer look at is the Brown Recluse.

Brown Recluse

The brown recluse spider, also known as the brown spider or fiddleback spider, is a soft bodied, secretive species that is light tan to dark brown in color. The adult spider is about half an inch in length and has long, delicate legs which are covered with short, dark hairs. Distinguishing characteristics are the presence of three pairs of eyes arranged in a semicircle on the forepart of the head, a violin-shaped dark marking immediately behind the semicircle of eyes (with the neck of the violin pointing towards the bulbous abdomen), and the characteristically long legs.

The immature stages closely resemble the adults except for size and often a slightly lighter color.

Life Cycle and Habits
The eggs are deposited in off-white silken cases in sheltered, dark areas where the spiders live. The cases are approximately one-quarter to one-third of an inch in diameter. In the summer, spiderlings emerge from egg cases in 24-36 days. Forty or more spiderlings develop from each egg case. However, before leaving the egg case the spiderlings molt once and then abandon the egg case. Development is relatively slow and is generally influenced by weather conditions and the availability of food. However, with adequate food and mild temperatures, the brown recluse spider can reach maturity in 10-12 months. The spiders are capable of surviving for long periods of time without food or water. Female spiders may live from one to two years, but some have reached four to five years. During her life one to five egg sacs are produced.

Habitat
The spider is most active at night when it comes out in search of food. During the day, it rests in quiet, undisturbed places. In homes, spiders may be found in bathrooms, bedrooms,
closets, basements, cellars, and attics, as well as under furniture. Spiders are often found hiding in old clothes, in shoes, behind pictures, in storage boxes, in stacks of paper, on the undersides of tables and chairs, behind baseboards and floor facings, or in corners and crevices. Spiders also live outdoors under rocks and bark, and they are frequently found in barns, storage sheds, and garages. The presence of shed skins in and around residences may be indicative of infestations.

Effects of the Bite
The brown recluse is not aggressive and normally bites only when pressure is applied to it. People are often bitten when they put on clothing or shoes in which a spider is hiding, when they roll over on a spider in bed, or when they clean a storage area that the spider is inhabiting. Individuals react differently to the bite; some people may not be aware of the bite for two or three hours, while others may have an immediate painful reaction. A stinging sensation is usually followed by intense pain. Within eight hours, a small puss-filled blister usually rises, and a large area around the bite becomes red and swollen. The victim may become restless and feverish and have difficulty in sleeping. The local pain is frequently quite intense, and the skin area surrounding the bite remains red and hard to the touch for some time. The tissue affected locally by the cytotoxic venom is killed and gradually sloughs away, exposing the underlying muscle. Skin grafts are often necessary to repair severe damage.

Healing takes place slowly and may take six to eight weeks. Without prompt medical attention the end result of a bite can be a sunken scar, ranging from the size of a penny to a half-dollar. In case of a bite, the victim should consult a physician immediately, and, if possible, the spider which caused the bite should be captured for positive identification.

As yet, specific antivenom is not available for treatment; therefore, both local and systemic reactions have been treated symptomatically. Corticosteroids are considered specific for combating hemolysis and other systemic complications, but they should only be administered by a physician.

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