Black Widow vs. Brown Recluse Spiders

Black Widow Spider vs. Brown Recluse Spider

Black Widow Spider (left) and Brown Recluse Spider (right).

In the U.S., most spiders you will find are harmless, but the black widow spider and the brown recluse spider are exceptions. Both types of spiders are more common in the southern U.S. and in warm, dry climates. Within these areas they tend to be found in environments that are undisturbed such as basements, closets, attics, under sinks, or in wood piles.

What Types of Dangers Would You Expect From a Black Widow Bite?

One of the dangers of a black widow spider bite is its effects on the nervous system.

The bite of a black widow spider is dangerous because it can affect a person's nervous system. The spider produces a neurotoxic protein that is extremely potent. Some people may have a minimal reaction, but others may suffer from a severe response.

Black Widow Victims May Experience These Symptoms:

Victims can suffer various symptoms from a black widow bite.

Symptoms of a black widow spider bite start within an hour after being bitten. Symptoms include severe muscle cramps, abdominal pain, weakness, and tremor. In severe cases symptoms may include nausea, vomiting, faintness, dizziness, chest pain, and respiratory difficulties.

What Type of Dangers Would You Expect From a Brown Recluse Spider?

The brown recluse venom is extremely poisonous, even more potent than that of a rattlesnake.

Another toxic spider is the brown recluse, whose venom is more potent than that of a rattlesnake, and is toxic to cells and tissues. However, because the bite releases much smaller quantities of poison into its victims, brown recluse bites cause less damage than rattlesnake bites.

Brown Recluse Victims May Experience These Symptoms:

Symptoms for a brown recluse bite usually develop two to eight hours after a bite.

Brown recluse spider bites may not even be noticed at first as they are often painless. Some people may notice minor stinging such as that felt with a bee sting when bitten by the spider. Symptoms of a brown recluse spider bite develop within eight hours after being bitten and include severe pain at the bite site, severe itching, nausea, vomiting, fever, and muscle pain.

Who Is the Black Widow Spider?

The black widow name is derived from the mistaken belief that the female invariably kills the male after mating.

The black widow spider gets its name from the erroneous belief that the female spider kills the male after mating. There are five species of black widow spiders in the U.S.; the southern black widow and the northern black widow are the most common. The spider is medium-sized and about half-inch long.

Who Is the Southern Black Widow Spider?

The southern black widow spider is characterized by its distinctive red hour glass marking.

The southern black widow spider is one of the two commonly found species of black widow spiders found in the U.S. and can be identified by its shiny, black, globular abdomen with the distinctive red hourglass shape on its underside.

Who Is the Northern Black Widow Spider?

The northern black widow spider is recognized by its row of red spots (upper surface) and two crosswise bars (undersurface).

The northern black widow spider doesn't have the hallmark red hourglass shape on its belly, instead it can be identified by a row of red spots (spots may also be yellow or white) down the middle of the upper surface of its abdomen, and two crosswise bars on the undersurface. The spider may be brown or have red legs.

Who Is the Brown Recluse Spider?

Brown recluse spiders are native to the Midwestern and Southeastern states.

Brown recluse spiders are native to the U.S. Midwest and Southeast. It is rare to find them outside these areas. There are 13 other species of spider in the same family that may be falsely identified as a brown recluse.

Who Are the Non-Brown Recluse Spiders?

Non-brown recluse spider.

Spiders in the same family as the brown recluse spider include the desert recluse found in Texas, Arizona, and California, and the Arizona recluse. Bites from these spiders may cause some localized skin disease, but no deaths have been reported from non-brown recluse spiders.

Who Is the Brown Recluse Spider?

Brown recluse spiders are notable for their characteristic violin pattern on the back.

Brown recluse spiders are identified by their characteristic violin pattern on the back of the cephalothorax (the part of the body where the legs attach). The base of the violin appears to be at the head of the spider and the neck of the violin points to the rear. Brown recluse spiders are small with one-inch legs, non-hairy, yellow-tan to dark brown in color, and darker legs. Most spiders have eight eyes, but the brown recluse has just six – it belongs to the genus Loxosceles. This feature is usually too small for people to see with the naked eye.

What Are the Habits of a Black Widow?

Male and female black widow spiders with egg sac.

Black widow spiders are active at night (nocturnal), and they prefer dark areas. They tend to avoid houses where people live, but they may be found in garages or sheds. Only female black widow spiders bite humans, and they only do so if disturbed.

What are the Habits of a Brown Recluse Spider?

Brown Recluse Spider.

Brown recluse spiders are not aggressive and will only bite if they feel threatened. They prefer dark, warm, dry environments such as attics, closets, basements, barns, and wood piles. Most brown recluse bites occur during the summer. The spider searches for prey at night and rests in the day in its small web, which is usually constructed in corners or crevices.

What Does a Black Widow Spider Bite Look Like?

The initial bite of a black widow spider may only show a minimal local reaction.

A black widow spider bite may appear as double fang marks at the site of the bite. The bite is described as feeling like a pinprick, though there may only be a small localized reaction. Blood pressure or heart rate may rise. The severity of the reaction to the bite depends on the age and overall health of the victim. Children and the elderly are usually more seriously affected.

Progression of Black Widow Spider Bite.

Example of a back widow spider bite several hours (left) to several days later (right).

Hours after being bitten by the black widow spider, the bite injury will swell. In the case pictured, two days after being bitten the redness and swelling continued past the elbow and down the forearm of the victim. Eight days after the bite, the swelling went down, the bite opened, and the infection was nearly gone.

What Does a Brown Recluse Spider Bite Look Like?

Example of a brown recluse spider bite three days after the bite.

A brown recluse spider bite may appear slightly red and when you look closely you may see fang marks. In most cases, the bite site will become firm and will heal over the following days to weeks with minimal scarring. In some cases the local reaction will be more severe with redness, blistering, blue discoloration, tissue death, and scarring. Pictured: the bite area swelled to quarter-size within an hour, and within a day continued to swell, turning blue and dark red.

Progressed Brown Recluse Spider Bite (Day Three)

Example of a brown recluse spider bite nine days after the bite.

In severe cases, the reaction to a brown recluse spider bite can lead to death of the skin (necrosis) and subcutaneous fat. Pictured: the same patient as in the previous slide, after three days, with initial stages of skin necrosis.

Progression of Brown Recluse Spider Bite (Day Nine)

Example of a brown recluse spider bite 9 days after the bite.

As the reaction to the brown recluse spider bite progresses, severe necrotic lesions with deep, wide borders can result. Pictured: the same patient in the previous slides, eight days following the bite. The wound remained open the entire time for the spider's toxins to drain, and the patient needed constant intravenous antibiotics and pain medications.

Progression of Brown Recluse Spider Bite (Day 38)

Example of a brown recluse spider bite 38 days after the bite.

Eleven days after the brown recluse spider bite a five-inch wide area of dead tissue was removed, and a skin graft was needed. Pictured: skin graft results 38 days after the bite.

Progression of Brown Recluse Spider Bite (10 Months)

Example of a brown recluse spider bite 10 months after the bite.

Pictured: Ten months after the brown recluse bite, the wound is healed, with scarring.

When Should I Seek Medical Care For a Black Widow Spider Bite?

Seek emergency medical care for serious reactions to black widow spider bites.

Seek care immediately following a black widow spider bite at a hospital emergency department. Most doctor's offices or urgent care centers are not equipped to deal with these types of injuries. Treatment for pain may require narcotic pain relievers and antivenin to counter the effects of the spider venom, which can usually only be found in a hospital setting.

Are There Self-Care Home Treatments For a Black Widow Spider Bite?

Hot baths are helpful after a black widow bite because the pain is due primarily to muscle spasm.

For minor black widow spider bites, home care treatments are limited. Cold or awarm compresses and hot baths may help ease pain. Over-the-counter pain relievers such as acetaminophen (Tylenol) or ibuprofen (Advil, Motrin) may help for mild bites. Folk remedies do not work.

When Should I Seek Medical Care For a Brown Recluse Spider Bite?

Brown recluse bite victims should seek medical care the same day.

If you think you have been bitten by a brown recluse spider see a doctor immediately or go to a hospital emergency department. If possible, bring the spider to the doctor's office so the physician can identify the spider to help make the proper diagnosis.

Are There Self-Care Home Treatments For a Brown Recluse Spider Bite?

Home first aid care is simple for a brown recluse bite but should not replace a visit to a doctor or emergency department.

Clean the wound area thoroughly with soap and water first, and then seek medical care. Home care is for relief of symptoms only after you have been treated by a doctor. Apply ice to decrease pain and swelling, and take acetaminophen (Tylenol) for pain. Elevate the area above the heart if possible. Avoid strenuous activity which can spread the spider venom through the skin.

Whose Bite Packs a Bigger Sting?

Black widow spider and brown recluse spider.

Be cautious of both black widow spiders and brown recluse spiders if bitten. Both can cause painful bites, which can be deadly in some cases. The brown recluse spider bite can cause severe blistering, blue discoloration, and necrotic lesions with scarring. However, the black widow spider bite can cause severe neurological symptoms especially in children or the elderly. Both types of spiders can be dangerous, and you should seek medical attention if bitten by either type of spider.



  1. Jeff Cleveland / BigStockPhoto
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  3. Lisa F. Young / BigStockPhoto (chest pain)
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    Ethan Myerson / iStockPhoto (injured hiker)
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  4. Clint Spencer / iStockPhoto (recluse)
    Steve McSweeny / BigStockPhoto (rattlesnake)
  5. Jon Schulte / iStockPhoto (nausea holding stomach)
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  9. Photo courtesy of Vickie Rauh
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  13. Photo courtesy of David O'Connor
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  25. MedicineNet


  • Centers for Disease Control and Prevention (CDC): "Venomous Spiders."
  • The Ohio State University: "Black Widow Spider."
  • University of California Agriculture & Natural Resources: "Brown Recluse and Other Recluse Spiders."
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