There are at least 50,000 spider species in the arachnid family. Spiders are defined as having eight jointed legs, no wings, no antennae and only two body sections: the thorax and the abdomen. Spiders spend their entire life span capturing and eating other insects (about 2,000 in a year). Even though spiders do a great deal of good for our environment, spiders are greatly feared by most of the population. Most spiders are killed only because they scare people, not because they are actually dangerous to humans.
- Black widow spider
- Brown recluse spider
- Chronic arachnidism or necrotic arachnidism
- Jumping spiders
- Wolf spiders
- Northwestern brown spider or the hobo spider
- Daddy longlegs spiders
All spiders have some amount of venom with varying degrees of potency. The fangs of a spider are hollow. The venom is injected through the fangs into the victim (usually an insect). The venom will rapidly paralyze the victim and aid in digestion. Fortunately, most spiders are not dangerous to humans because their fangs are either too short or too fragile to penetrate human skin.
Spiders do not attack in herds. Spiders do not lay in wait and attack people. Spiders do not lift the covers at night and crawl into bed to bite people as they are sleeping. Some spiders can jump but they are not intentionally jumping at humans to attack them. A spider generally bites a human because it was scared and bites to defend itself. Spiders generally prefer to live in undisturbed areas such as corners of the house or the eaves or in the garden where they can catch insects in peace.
Killing spiders with pesticides is difficult. Spraying surfaces is usually ineffective because the spider has minimal contact with the sprayed area. The actual spider or egg sacs must be sprayed with pesticide. The danger of a possible spider bite has to be weighed against the risk of over-using pesticides that probably will not work against spiders.
Bite marks from most spiders are usually too small to easily be seen. Frequently the patient will not recall being bitten. Many of the spider bites will result in pain, small puncture wounds, redness, itching and swelling that lasts a couple of days. Spiders rarely bite more than once, so multiple bites are usually caused by insects such as fleas, bedbugs, ticks, mites and biting flies.
Black widow spiderBlack widow spiders generally live in trash, closets, attics, woodpiles, garages and other dark places. They are found throughout California, especially in the warmer regions such as the Central Valley and Southern California. Only the female spider is dangerous to humans.
What does a black widow spider look like?
The black widow spider is a shiny, inky black spider with a large round tail segment (abdomen). Including its legs, the black widow generally measures from one-half inch to one inch in length. Red to orange-colored markings, usually in the shape of an hourglass, are found on the underside of the belly.
What are the symptoms of a bite?
A black widow spider bite gives the appearance of a target, with a pale area surrounded by a red ring. Severe muscle pain and cramps may develop in the first two hours. Severe cramps are usually first felt in the back, shoulders, abdomen and thighs. Other symptoms include weakness, sweating, headache, anxiety, itching, nausea, vomiting, difficult breathing and increased blood pressure. Young children, the elderly and those with high blood pressure are at highest risk of developing symptoms from a black widow spider bite.
How dangerous are black widow spider bites?
If a black widow spider bites a person, do not panic! No one in the United States has died from a black widow spider bite in over 10 years. Very often the black widow will not inject any venom into the bite and no serious symptoms develop. Wash the wound well with soap and water to help prevent infection.
If muscle cramps develop, take the patient to the nearest hospital. Some victims, especially young children, may be admitted overnight for observation and treatment. There is treatment for a black widow spider bite that can take care of the symptoms. Various medications are used to treat the muscle cramps, spasms and pain of a bite. Black widow spider antivenin is seldom necessary.
Brown recluse spiderWhat does a brown recluse spider look like?
Named for its habit of hiding in dark corners, the brown recluse spider (Loxosceles reclusa) is also known as the violin spider or fiddleback spider because of a violin-shaped marking. The brown recluse spider is about a half-inch long (including legs) and is a solid light brown color. The violin marking is configured with the base of the violin beginning at the eyes and the neck of the violin pointing toward the "waist." The violin marking is difficult to see clearly. Two other features can help identify the brown recluse: it has six eyes rather than the typical eight and the tail-end segment has no markings. If you see a brown spider with markings on the tail end, it cannot be a brown recluse spider. Any markings, patterns or spots on the tail end of a spider immediately eliminates the possibility that it is a brown recluse spider. It is, instead, one of dozens of brown spiders that live in houses and yards. They may bite, but they are not dangerous.
Where do brown recluse spiders live?
Spider experts across the state agree that the true brown recluse spider does NOT live in California, but is native to Kansas, Texas, Oklahoma and Mississippi. There are some related species found in California. The Loxosceles laeta, imported from South America, has been found in eastern Los Angeles County. The Loxosceles deserta is found in the Mojave and Sonoran deserts, the foothills of the Central Valley up to Merced and Fresno counties, but not in Northern California.
In any case, the brown recluse is called a "recluse" because it hides and is not commonly found out in the open. The brown recluse will hide in dark, quiet, out-of-the-way areas where it will not easily be disturbed.
What are the symptoms of a brown recluse spider bite?
The brown recluse spider bite usually causes some pain or burning in the first 10 minutes, accompanied by itching. The wound takes on a bull's-eye appearance, with a center blister surrounded by an angry-looking red ring and then a blanched (white) ring. The blister breaks open, leaving an ulcer that scabs over. The ulcer can enlarge and involve underlying skin and muscle tissue. Pain may be severe. A generalized red, itchy rash usually appears in the first 24-48 hours. Other symptoms include fever, chills, nausea, vomiting, muscle aches and hemolytic anemia (a condition where the red blood cells are destroyed).
People bitten by an unseen spider sometimes blame the brown recluse spider because their bite resembles a brown recluse spider bite. However, there are a number of other spiders and insects, as well as other medical conditions, that are capable of producing tissue wounds of similar appearance, but these are usually of a lesser severity.
What is the treatment for a brown recluse spider bite?
Treatment consists of washing the wound and applying an antibiotic ointment. The victim should seek medical attention if there are signs of an infection, an ulcer that does not heal, a bite accompanied by nausea, vomiting, fever or a rash. There is no special treatment or medication used to treat a brown recluse spider bite. If infection develops, antibiotics are used. If a wound becomes deep and infected, occasionally surgery is needed. Anytime there is a bite or a wound that is not healing and getting worse, see a physician for evaluation.
for more information on Brown Recluse Spiders...
by University of California Pest Management
Chronic arachnidismWhile most spider bites are not dangerous, there is a group of spiders that can produce bite wounds that look similar to a brown recluse spider bite. Unless the spider was actually seen, captured and brought to the physician, the brown recluse spider is not likely to be the culprit. Some of the spiders in this group that can cause a nasty bite include the running spider, jumping spider, wolf spider, tarantula, sac spider, orbweaver spider and the northwestern brown spider, also known as the hobo spider.
or necrotic arachnidism
What are the symptoms of a bite from these kinds of spiders?
In most cases of bites from these spiders, there is pain or burning at the bite site in the first 10 minutes. The bite from this group is usually described as looking like a "target" or "bull's-eye." The center of the wound is usually a blister surrounded by a reddened area. A pale or blanched area may surround the discolored reddened area. The blister may rupture, leaving an open ulcer. In severe cases the ulcer can become deep and infected causing tissue breakdown or tissue death (necrosis).
Worsening pain, itching and a burning sensation develop. A patient may also have symptoms such as a red, itchy rash over the torso, arms and legs that is usually seen in the first 24-72 hours. Patients may have pain in the muscles and joints, fever, chills, swollen lymph nodes, headaches, and nausea and vomiting.
How are these bites treated?
Frequently, when people with spider bites call the Poison Center, they think there is some special treatment that is necessary for their bite. There is no specialized therapy other than treating the symptoms. Most importantly, keep the wound clean to prevent infection. If the wound does not heal or does develop an infection, see your physician. Do not wait days and weeks while the wound continues to get worse.
There are tales of people having limbs amputated after spider bites. These involve people who refused to see a physician even though they had massive wounds that did not heal and became grossly infected. A wound that may have been originally treated with simple oral antibiotics, but left untreated, may require surgical intervention in extreme cases.
What else can cause a nasty looking wound?
Kissing bugs, fleas, bed bugs, flies, mites, wasps, ants and blister beetles have produced lesions similar to a brown recluse spider bite. Many skin disorders and medical conditions can produce lesions that can also mimic a brown recluse spider bite. Some of these include infected herpes outbreaks, bedsores, diabetic ulcers, poison oak and Lyme disease. Again, use common sense: If there is a wound that is not healing as expected or getting worse, see a physician.
Jumping spidersThe jumping spider is probably the most common biting spider in the United States. People are caught by surprise and scared when they see the spider jump, especially if it jumps towards them. Bites from a jumping spider are painful, itchy and cause redness and significant swelling. Other symptoms may include painful muscles and joints, headache, fever, chills, nausea and vomiting. The symptoms usually last about 1-4 days.
Wolf spidersWolf spiders are commonly found in California. They are large hairy spiders, up to 3-4 inches across. They are a mottled gray-brown color, which helps them hide in sand, gravel, leaves and other debris. Female wolf spiders carry their young on their backs. Except for one group, wolf spiders do not spin webs. They tend to burrow into the earth and hide. They are aggressive, come after their prey and are fast runners. Because of their impressive size and aggressiveness, wolf spiders can easily incite panic.
Bites from a wolf spider can cause pain, redness and swelling. The large jaws/fangs can cause a tear in the skin as they bite. Swollen lymph glands may develop. The skin area at the bite may turn black. Swelling and pain can last up to ten days.
TarantulasTarantulas are also large hairy spiders. In fact, some people call any large hairy or fuzzy spider a tarantula. Tarantulas are very hairy with sharp bristles. The hairs are easily shed or can be rubbed off. Handling a tarantula can result in irritation to the skin. If hands are not washed after handling a tarantula and eyes are touched, the sharp hairs can cause eye irritation that may require a trip to the physician.
Tarantulas are sensitive to vibrations and hunt at night by touch. If cornered, the tarantula will make a purring sound and may rear up on its back legs. Even though tarantulas are scary looking to most people, most bites do not produce any significant poisoning symptoms. However, the bites can be quite painful because of the large size of the spider.
Wash your hands well with soap and water after handling a tarantula.
Northwestern brown spider or the hobo spiderThe northwestern brown spider or hobo spider (Tegenaria agretis) is well known in Oregon and Washington and is also quite common in Utah. Spider bites by this spider are becoming recognized more often in California, which may be due to the fact that the spider is becoming better known. The hobo spider often causes a bite that leaves an open, slow-healing wound. Bites from this spider are frequently and mistakenly thought to be brown recluse spider bites.
Keep the wound clean and prevent infection. If the bite becomes infected or does not seem to heal, see a physician.
Daddy longlegs spidersThe Daddy Longlegs is not a true spider in that it cannot make silk and does not have fangs or venom glands. Daddy Longlegs have long thin legs with flexible claw-like "fingers". Daddy Longlegs can pinch but rarely penetrate human skin.
They have scent glands on the front part of their bodies that can give-off a bad-smelling fluid. This stinky fluid is used as a defense mechanism to keep enemies away. Some people might have a reaction to the fluid but Daddy Longlegs are not considered dangerous to humans.
Daddy Longlegs are usually found hanging upside down in corners, eaves or basements. They are very common and are found in most homes. Because they eat insects and other spiders, they are considered beneficial.
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