What are the most common poisonous spiders in Northern California. How can you prevent spider bites. What are the symptoms of a venomous spider bite. When should you seek medical attention for a spider bite.

Common Poisonous Spiders in Northern California

Northern California is home to several species of spiders, but only a few are considered potentially dangerous to humans. The most notable poisonous spiders in the region include:

• Black Widow Spider (Latrodectus hesperus)
• Brown Widow Spider (Latrodectus geometricus)
• Yellow Sac Spider (Cheiracanthium inclusum)
• Hobo Spider (Eratigena agrestis)

While other spiders may bite, these species are known to have venom that can cause significant health issues in humans. It’s important to note that most spiders are actually beneficial, helping to control insect populations, and will only bite humans as a defense mechanism when threatened.

Identifying Venomous Spiders in Northern California

Recognizing potentially dangerous spiders is crucial for prevention and prompt treatment if bitten. Here are some key characteristics of the most common venomous spiders in Northern California:

Black Widow Spider

The black widow is perhaps the most infamous spider in the region. How can you identify a black widow spider?

• Shiny black body
• Red hourglass shape on the underside of the abdomen
• Females are larger, measuring about 1.5 inches long including legs
• Males are smaller and often brown or gray in color

Brown Widow Spider

The brown widow is a close relative of the black widow but is less common in Northern California. Identifying features include:

• Mottled brown or tan coloration
• Orange or yellowish hourglass shape on the underside of the abdomen
• Spiny egg sacs, unlike the smooth sacs of black widows

Yellow Sac Spider

These small spiders are often found in homes and gardens. Key characteristics are:

• Pale yellow or beige color
• Dark fangs visible at the front of the head
• About 1/4 to 3/8 inch long
• Often found in silk sacs in corners or on plants

Hobo Spider

While less common, hobo spiders can be found in some parts of Northern California. Identifying features include:

• Brown coloration with chevron patterns on the abdomen
• Long legs
• About 1/3 to 2/3 inch in body length
• Often confused with other brown spiders

Spider Bite Prevention Strategies

Preventing spider bites is far easier and safer than dealing with the aftermath of a bite. Here are some effective strategies to minimize your risk of spider bites:

1. Seal entry points: Inspect your home for cracks, gaps, and openings that spiders might use to enter. Seal these with caulk or other appropriate materials.
2. Reduce clutter: Spiders love hiding in cluttered areas. Keep your home, garage, and yard tidy to minimize potential spider habitats.
3. Use protective clothing: When working in areas where spiders might be present, such as garages or gardens, wear long sleeves, pants, and gloves.
4. Shake out stored items: Before using items that have been stored for a while, such as shoes or gardening gloves, shake them out to dislodge any hiding spiders.
5. Keep beds away from walls: Position beds and cribs away from walls to reduce the likelihood of spiders crawling onto them.
6. Regular cleaning: Vacuum and dust regularly, paying special attention to corners, baseboards, and under furniture where spiders often build webs.
7. Use natural repellents: Certain essential oils, like peppermint or tea tree oil, can help repel spiders when diluted and sprayed in prone areas.
8. Remove outdoor hiding spots: Keep woodpiles, leaf litter, and other debris away from the foundation of your home.

By implementing these prevention strategies, you can significantly reduce the chances of encountering venomous spiders in and around your home.

Symptoms of Venomous Spider Bites

Recognizing the symptoms of a venomous spider bite is crucial for timely treatment. While symptoms can vary depending on the spider species and individual reactions, here are some common signs to watch for:

Black Widow Spider Bite Symptoms

• Immediate sharp pain at the bite site
• Redness and swelling
• Severe muscle cramps and abdominal pain
• Nausea and vomiting
• Sweating and fever
• Increased blood pressure

Brown Widow Spider Bite Symptoms

Brown widow bites are generally less severe than black widow bites but can still cause:

• Localized pain and redness
• Mild to moderate swelling
• Occasional nausea or headache

Yellow Sac Spider Bite Symptoms

• Immediate stinging sensation
• Redness and swelling at the bite site
• Itching or burning sensation
• Small blister formation

Hobo Spider Bite Symptoms

The severity of hobo spider bites is debated, but potential symptoms include:

• Redness and swelling
• Slow-healing wound
• Headache and fatigue
• In rare cases, necrotic lesions (though this is controversial)

It’s important to note that many spider bites may be misidentified, and other conditions can mimic spider bite symptoms. When in doubt, seek medical attention, especially if symptoms worsen or persist.

First Aid for Spider Bites

If you suspect you’ve been bitten by a venomous spider, taking quick and appropriate action can help minimize complications. Here’s a step-by-step guide for spider bite first aid:

1. Clean the bite area: Wash the affected area thoroughly with soap and water to reduce the risk of infection.
2. Apply a cold compress: Use an ice pack or cold, damp cloth to reduce pain and swelling. Apply for 10 minutes at a time with breaks in between.
3. Elevate the affected area: If the bite is on an extremity, elevate it to reduce swelling.
4. Take over-the-counter pain relievers: Acetaminophen or ibuprofen can help manage pain and inflammation.
5. Monitor symptoms: Keep a close eye on the bite area and your overall condition. Look for signs of worsening or spreading symptoms.
6. Seek medical attention: For suspected black widow bites or if symptoms are severe or worsening, seek immediate medical care.

Do not attempt to catch the spider by hand, but if possible, try to safely capture it or take a clear photo for identification purposes. This can help medical professionals determine the best course of treatment.

When to Seek Medical Attention for Spider Bites

While many spider bites can be treated at home, certain situations require professional medical care. You should seek immediate medical attention if:

• You suspect a black widow spider bite
• You experience severe pain, muscle cramps, or abdominal pain
• You develop signs of an allergic reaction, such as difficulty breathing or widespread hives
• The bite area develops a large, growing rash or begins to show signs of infection
• You experience fever, chills, or other systemic symptoms
• The bite victim is a young child, elderly, or has a compromised immune system

In these cases, don’t wait – seek emergency medical care or call your local poison control center for guidance. Prompt treatment can prevent serious complications and ensure a faster recovery.

Spider Control and Management in Northern California

While complete elimination of spiders is neither possible nor desirable due to their beneficial role in controlling other pests, you can take steps to manage spider populations around your home. Here are some effective spider control strategies:

Habitat Modification

Reducing favorable conditions for spiders can significantly decrease their presence:

• Remove webs regularly using a broom or vacuum
• Minimize outdoor lighting, which attracts insects that spiders feed on
• Keep vegetation trimmed away from your home’s foundation
• Seal cracks and crevices in walls, windows, and doors

Natural Predators

Encouraging natural spider predators can help keep populations in check:

• Birds: Install bird feeders and baths to attract insect-eating birds
• Lizards: Create habitats for lizards, which feed on spiders
• Cats: If you have outdoor cats, they may help control spider populations

Chemical Control

While not always necessary, chemical controls can be used as a last resort:

• Use spider-specific insecticides in targeted areas
• Apply residual sprays around windows, doors, and other entry points
• Consider professional pest control services for severe infestations

Remember, spiders play a crucial role in controlling other insect populations. Aim for management rather than complete eradication to maintain a balanced ecosystem around your home.

Educating Children About Spider Safety

Teaching children about spider safety is crucial for preventing bites and fostering a healthy respect for these creatures. Here are some key points to cover when educating children about spiders:

Identification

Help children learn to identify common spiders in your area, especially those that may be dangerous. Use pictures or safe, preserved specimens to teach them about spider anatomy and distinguishing features.

Respect, Don’t Fear

Encourage a balanced view of spiders. Explain their important role in nature and how most spiders are harmless to humans. Teach children to respect spiders from a distance rather than fearing them.

No-Touch Rule

Establish a firm rule about not touching or trying to catch spiders. Teach children to alert an adult if they see a spider indoors or in an area where they play.

Proper Clothing

Instruct children on wearing appropriate clothing when playing outdoors, especially in areas where spiders might be present. This includes closed-toe shoes, long pants, and long-sleeved shirts when necessary.

What to Do If Bitten

Teach children to immediately tell an adult if they think they’ve been bitten by a spider. Explain the importance of being able to describe where they were and what the spider looked like if possible.

Outdoor Awareness

Educate children about common spider habitats outdoors. Teach them to be cautious when playing in woodpiles, under rocks, or in dense vegetation.

By educating children about spider safety, you can help prevent accidental bites and foster a generation that understands and appreciates the role of spiders in our ecosystem.

Poisonous Bites · California Poison Control System (CPCS)

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California is home to many critters, insects, and spiders that bite. Bites vary in severity based on the person, type of bite, and the bite site.

Learn how you can stay safe and prevent poisonous bites by following the tips below.

About Poisonous Bites

Most bites lead to unpleasant reactions such as an itchy bump. However, you may have stronger, life-threatening reactions if you are allergic to the venom (see anaphylaxis below). Venom is considered a poisonous substance created by critters, insects, and spiders.

Bite Precautions

• Mosquitoes may carry West Nile Virus. If fever, headaches, and nausea occur from a mosquito bite, contact your physician immediately.
• Rattlesnake bites are life-threatening. If bitten by a rattlesnake call 9-1-1 immediately.
• Spider bites (example: Black Widow) can result in uncomfortable to severe symptoms. If you are concerned about your symptoms, call the California Poison Control System for advice. If your symptoms are severe, go to the emergency room.
• Ticks can carry Lyme disease and if fever, rash, or vomiting occurs, you should also contact your physician immediately.

General Bite Symptoms

• Fever
• Hives
• Pain/Itching
• Redness
• Swelling
• Warmth around the bite site

Rattlesnake Bite Symptoms

• Visit the Rattlesnakes page to learn more.

Spider Bite Symptoms

• Dizziness
• Fever/Chills
• Headache
• Pain/Itching
• Redness
• Stiffness
• Stomach pain or cramping
• Swelling

Anaphylaxis

Anaphylaxis is a severe, potentially life-threatening allergic reaction. Call 911 right away if you have any of the following symptoms.

• Chest tightness
• Difficulty breathing or wheezing
• Difficulty talking or confusion
• Pale or red face
• Rash over the whole body
• Sever pain, cramping, or swelling
• Shock
• Spreading redness or red streaks

First Aid Tips

• For bites
  • Cleanse the site with soap and water.
  • Use an ice pack to reduce pain or swelling.
  • Reasons to go to the doctor after a spider bite include severe discomfort, spreading local redness accompanied by pain, and any drainage from a bite site.
• For anaphylaxis
  • Use an EpiPen (epinephrine autoinjector) right away. If you do not have one, call 911 immediately.

Prevent Poisonous Bites

If you come across critters, insects, or spiders, keep your distance.

General Bites Prevention

• When outdoors, apply insect repellants that contain DEET to all exposed skin areas.
• Wear protective clothing for yard work or around grassy areas, such as:
  • Hats
  • Long sleeves and long pants
  • Gloves
  • Closed-toe shoes

Rattlesnake Bite Prevention

• Visit the Rattlesnakes page to learn more.

Spider Bite Prevention

• Do not agitate spiders. They typically only bite if they feel threatened.
• Keep cribs and beds as far from walls as possible.
• Before getting dressed, shake out clothing, shoes, and hats that you have not worn for a while.
• If a bed has not been slept in for awhile, check the sheets and covers thoroughly before climbing in.
• Always put on gloves and long-sleeved shirts when going through or emptying closets, boxes, containers, or when handling fire wood, lumber, and any items you have been storing for a long time.
• Clean and get rid of clutter in the basement, attic, garage, storage, and closets in and around your home.
  • Remove spiderwebs and spiders.
  • Dust and vacuum around windows, corners of rooms, under furniture, and in storage areas.

Related Topics

• Materials
• Video: Spider Bite, California Poison Control System PSA

Spider Management Guidelines–UC IPM

UC IPM Home > Homes, Gardens, Landscapes, and Turf > Spider Spiders Revised 10/20 In this Guideline: Identification Management Spider bites About Pest Notes Publication Glossary Related videos Common garden spiders How to catch a spider How to clean up spider webs Common garden spiders (2:13) Wolf spider. Female Western black widow spider. Yellow sac spider. Common house spider. Marbled cellar spider. Many people fear or dislike spiders but for the most part, spiders are beneficial because of their role as predators of insects and other arthropods, and most cannot harm people. Spiders that might injure people—for example, black widows—generally spend most of their time hidden outside homes in woodpiles or in clutter in the garage. The spiders commonly seen out in the open during the day are unlikely to bite people. IDENTIFICATION Spiders resemble insects and sometimes are confused with them, but they are arachnids, not insects. Spiders have 8 legs and 2 body parts—a head region (cephalothorax) and an abdomen. They lack wings and antennae. Common spider families are described in Table 1. Most spiders have venom which they use to kill their prey. However, only those spiders whose venom typically causes a serious reaction in humans are called “toxic” spiders. See Spider Bites. Black Widow Spider The black widow spider, Latrodectus hesperus, is the most common harmful spider in California. Venom from its bite can cause reactions ranging from mild to painful and serious, but death is very unlikely and many symptoms can be alleviated if medical treatment is obtained. Anyone bitten by this spider should remain calm and promptly seek medical advice. It is helpful if the offending spider can be caught and saved for identification by an arachnologist. The typical adult female black widow has a shiny black body, slender black legs, and a red or orange mark in the shape of an hourglass on the underside of the large, round abdomen. In contrast, immature and male western black widows have white stripes on a tan abdomen and look very different from the adult females. Only the larger immature female and adult female spiders are able to bite through a person’s skin and inject enough venom to cause a painful reaction. The adult male black widow is one-half to two-thirds the length of the female, has a small abdomen, and is seldom noticed. The male black widow does possess venom, but its fangs are too small to break human skin. Contrary to popular belief, the female black widow rarely eats the male after mating but may do so if hungry. The web of the black widow is an irregular, tough-stranded, sticky cobweb mesh in which the spider hangs with its underside up, showing the red hourglass. The egg sacs are mostly spherical, about 1/2 inch long and 1/2 inch in diameter, creamy yellow to light tan in color, opaque, and tough and paperlike on the surface. Black widow spiders occur in most parts of California. They and their associated webs usually are found in dark, dry, sheltered, relatively undisturbed places. People are most likely to be bitten when they disturb the spider while they are cleaning out or picking up items in such places. The symptoms of a black widow bite are largely internal; little more than local redness and swelling may develop at the bite site. The internal effects may range from mild to severe. Small children, the elderly, and persons with health problems are likely to suffer some of the more severe consequences of the bite. Black widow bites are fairly common in California. For more information about black widows, see Pest Notes: Widow Spiders and Their Relatives. Yellow Sac Spider The common, house-dwelling yellow sac spider, Cheiracanthium mildei, is a small spider that spins a silken sac web in the corners of ceilings and walls, and behind shelves and pictures; it is also commonly found outdoors in shrubbery. This spider is light yellow and has a slightly darker stripe on the upper middle of the abdomen.The 8 eyes of this spider are all about equal in size and arranged in 2 horizontal rows. Yellow sac spiders can be seen running on walls and ceilings at night and quickly drop to the floor to escape if they are disturbed. Bites usually occur when the spider becomes trapped against a person’s skin in clothing or bedding. Typical symptoms of a bite include initial pain similar to a bee sting, redness, and sometimes swelling. Recluse Spiders Recluse spiders of the genus Loxosceles include the well-known brown recluse spider, L. reclusa, which does not occur in California. While the brown recluse has occasionally been brought into California in household furnishings, firewood, and motor vehicles, there are no breeding populations in the state. Related native recluse species are found in California’s southeastern deserts. Recluse spiders can have a violin-shaped mark (with the neck of the violin pointing backward) on the top side of the head region (cephalothorax). However, the mark is not always distinct, so it should not be used as an identifying character. A more diagnostic feature of recluse spiders is their 6 eyes, arranged in pairs in a semicircle, which can be seen with the use of a good hand lens. Most other spiders have 8 eyes. More detailed information on these spiders is available in Pest Notes: Brown Recluse and Other Recluse Spiders. Other Spiders In addition to the species mentioned above, there are only a few other species of spiders in California that may on occasion bite humans. (Remember, if the bite of any spider causes an unusual or severe reaction, contact a physician). One kind of red and black jumping spider, Phidippus johnsoni, may bite if it is disturbed, but the bites are usually not serious. The female spiders are black with red on the top side of the abdomen whereas the males have a black cephalothorax with an all red abdomen. These spiders range in size from ¼ to ½ inch long. Tarantulas are long-lived spiders that occupy burrows in the ground during the day but wait at at their burrow entrance at night to prey on insects passing near the burrow. They commonly are feared because of their large size and hairy appearance. These spiders range from 1 to 2 inches in body size. Some tarantulas that occur in tropical parts of the world have bites toxic for humans, but the bites of California tarantulas are not likely to be serious—at worst, they are similar to a bee sting. However, because of the variety of tarantulas sold in the pet trade industry, there is a spectrum of venom potencies among these creatures. The hobo spider, Eratigena agrestis, is a common spider in the northwestern United States and British Columbia. It builds webs in dark, moist areas such as basements, window wells, wood piles, under driftwood, and around the perimeter of homes. It is a large (1 to 1 3/4 inch, including legs), fast-running brown spider with a herringbone or multiple chevron pattern on the top of the abdomen. The hobo spider has not been documented in California, but it has expanded its range from the Pacific Northwest to northern Utah, Wyoming, and Colorado. Although it has been stated as being a toxic spider, recent research is challenging the original data that elevated this spider to medical importance. See Pest Notes: Hobo Spider, listed in the References section. One spider frequently found indoors is the common house spider, Parasteatoda tepidariorum, which makes a cobweb in corners of rooms, in windows, and in similar places. Another is the marbled cellar spider, Holocnemus pluchei, which was introduced into the state in the 1970s and has since displaced the once common longbodied cellar spider, Pholcus phalangioides, a long-legged spider that resembles a daddy-longlegs. These spiders are only marginally capable of biting humans because their fangs are too short to pierce people’s skin in most cases; they primarily cause problems by producing messy cobwebs. Various kinds of small hunting spiders may wander indoors and occasionally, rather large, hunting-type spiders are discovered in homes or garages. Often these are fully grown wolf spider or tarantula males that have reached maturity and are searching for females. When these spiders are wandering, one or more may accidentally get indoors. New houses and other structures in developments may be invaded by wolf spiders that have lost their usual outdoor living places. The more insects that exist inside a building, the more likely it is to have spiders living there. Immature and adult female burrow-living spiders sometimes wander for a time during the rainy season if they have had to abandon wet burrows. Table 1. Common Spider Families in North America. Agelenidae, funnel weavers or grass spiders Sit-and-wait predators feed during the day and night near the ground in most types of vegetation, including low-growing plants and trees. Spin funnel-shaped webs, often with several-inch-wide, flat extension covering plants or soil. The spider waits in the hole of its web. When it detects vibrations from an insect that flew or walked into the web, the spider runs out, captures and bites the prey, then carries it back into the funnel to be eaten. Webs on low vegetation become conspicuous in morning light after collecting dew. Funnel weavers have 6 or 8 eyes, all about the same size, arranged in 2 rows. About 300 species in North America. Araneidae, orb weavers or garden spiders Feed on insects that fly, fall, or are blown into web. Elaborate silken webs are spun in concentric circles. Spiderlings often make symmetrical webs; mature spiders may spin a more specialized design that is helpful in identifying certain species. The spider rests at the center of its web or hides in a shelter near the edge, waiting for prey to become entangled. Orb weavers generally have poor vision and rely on web vibrations to locate and identify prey. About 200 species in North America. Clubionidae (including Corinnidae), sac spiders or twoclawed hunting spiders Stalk and capture prey that is walking or resting on surfaces. They spin silken tubes or sacs under bark, among leaves, and in low plants or on the ground, where they hide during the day or retreat after hunting. Commonly are nocturnal, medium-sized, pale spiders with few markings. About 200 species in North America. Linyphiidae (=Microphantidae), dwarf spiders Prey on insects that fall, walk, or land in their web. Diurnal (day active) spiders occurring in the plant canopy and among litter on the ground. They produce sheetlike webs on the surface of plants or soil and are common in some field and vegetable crops. Most are relatively small. Several hundred species in North America. Lycosidae, wolf spiders Prey on insects that are walking or resting on the ground. Actively hunt in the open during the day and night, often observed on the ground in litter and on low vegetation. Can occur in burrows and under debris on soil. Instead of spinning webs to catch prey, make a small, thick web where they rest. Have a distinctive pattern of eyes: four small eyes in front in a straight row, one middle pair of larger eyes, and one rear pair of widely spaced eyes on top of the head. They have long hairy legs. They are usually black and white or strongly contrasting light and dark, which can make them difficult to discern unless they are moving. About 200 species in North America. Oxyopidae, lynx spiders Stalk and capture resting or walking insects. Active hunters with good vision. Most have spiny legs and a brightly colored body that tapers sharply toward the rear. They have four pairs of eyes grouped in a hexagon. About 2 dozen known species in North America. Salticidae, jumping spiders Day-active hunters in plants or on the ground. They make no web; instead they stalk and pounce on prey by jumping distances many times their body length. Jumping spiders have a distinctive pattern of eyes in three rows: the first row of four eyes, with large and distinctive middle eyes; a second row of two very small to minute eyes; and a third row of two medium sized eyes. They usually have an iridescent, metallic-colored abdomen and black carapace. About 300 species in North America. Theridiidae, cobweb, cobweb weaver, or combfooted spiders Feed on insects that walk or fly into their webs. Almost always found hanging upside down by their claws in irregularly spun, sticky webs, waiting for prey. The spider is usually concealed in a corner of the web, in a silken tent, or behind debris. This group includes the black widow spider, which produces relatively thick silk that feels rough and sticky. They generally have a soft, round, bulbous abdomen and slender legs without spines. Over 200 species in North America. Thomisidae, crab spiders or flower spiders Stalk and capture insects walking or resting on surfaces. Diurnal hunters that do not spin webs. Front two pairs of legs are enlarged and extend beyond the side of their flattened body, making them look like tiny crabs. Their small eyes occur in two slightly curved rows, with the top row often much wider than the lower row. Over 200 species in North America. MANAGEMENT How to catch a spider (1:10) Spiders may enter houses and other structures through cracks and other openings. They also may be carried in on items like plants, firewood, and boxes. To prevent spiders from coming indoors, seal cracks in the foundation and other parts of the structure and gaps around windows and doors. Good screening not only will keep out many spiders but also will discourage them by keeping out insects that they prey upon. Regular vacuuming or sweeping of windows, corners of rooms, storage areas, basements, and other seldom used areas helps remove spiders and their webs. Vacuuming spiders can be an effective control technique because their soft bodies usually do not survive the tumbling process through the hose. Indoors, a web on which dust has gathered is an old web that is no longer being used by a spider because occupied spider webs are maintained for cleanliness to enhance prey capture. Individual spiders can also be removed from indoor areas by placing a jar over them and slipping a piece of paper under the jar that then seals off the opening of the jar when it is lifted up. They can then be released outdoors. Watch this video to learn more: How to catch a spider. In indoor storage areas, place boxes off the floor and away from walls, whenever possible, to help reduce their usefulness as a harborage for spiders. Sealing the boxes with tape will prevent spiders from taking up residence within. Clean up clutter in garages, sheds, basements, and other storage areas. Be sure to wear gloves to avoid accidental bites. Outdoors, eliminate places for spiders to hide and build their webs by keeping the area next to the foundation free of trash, leaf litter, heavy vegetation, and other accumulations of materials. Trimming plant growth away from the house and other structures will discourage spiders from first taking up residence near the structure and then moving indoors. Outdoor lighting attracts insects, which in turn attracts spiders. If possible, keep lighting fixtures off structures and away from windows and doorways. Sweep, mop, hose, or vacuum webs and spiders off buildings regularly. Chemical Control Insecticides will not provide long-term control and should not generally be used against spiders outdoors. Typically, controlling spiders with pesticides 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, including pyrethrins and pyrethroids (synthetic versions of pyrethrins) such as resmethrin, allethrin, or combinations of these products. Control by spraying is only temporary unless accompanied by housekeeping. It is just as easy and much less toxic to crush the spider with a rolled up newspaper or your shoe or to vacuum it up. Sticky traps offer a noninsecticidal way to remove spiders from your home as long as you can place the traps where pets and children can’t tamper with them. Sorptive dusts containing amorphous silica gel (silica aerogel) and pyrethrins, which can be applied by professional pest control applicators only, may be useful in certain indoor situations. Sorptive dust particles affect the outer covering of spiders (and also insects) that have crawled over a treated surface, causing them to dry out and die. When applied as a dustlike film and left in place, a sorptive dust provides permanent protection against spiders. The dust is most safely and effectively used in cracks and crevices and in attics, wall voids, and other enclosed or unused places. SPIDER BITES Unlike mosquitoes, spiders do not seek people in order to bite them. Generally, a spider doesn’t try to bite a person unless it has been squeezed, lain on, or similarly provoked to defend itself. Moreover, the jaws of most spiders are so small that the fangs cannot penetrate the skin of an adult person. Sometimes when a spider is disturbed in its web, it may bite instinctively because it mistakenly senses that an insect has been caught. The severity of a spider bite depends on factors such as the kind of spider, the amount of venom injected, and the age and health of the person bitten. A spider bite might cause no reaction at all, or it might result in varying amounts of itching, redness, stiffness, swelling, and pain—at worst, usually no more severe than a bee sting. Typically, the symptoms persist from a few minutes to a few hours. Like reactions to bee stings, however, people vary in their responses to spider bites, so if the bite of any spider causes an unusual or severe reaction, such as increasing pain or extreme swelling, contact a physician, hospital, or poison control center (in California, the number is 1-800-876-4766 or 1-800-8-POISON). One must also keep in mind that although it is impossible to be certain, people and their physicians often blame spiders as the cause of skin lesions with no proof of spider involvement when there are many similar-appearing, non-spider maladies; therefore, care must be exerted in the diagnostic process. Sometimes a person may not be aware of having been bitten until pain and other symptoms begin to develop. Other species of arthropods whose bites or stings may be mistaken for that of a spider include ticks, fleas, bees, wasps, bedbugs, mosquitoes, the conenose (kissing) bug (Triatoma protracta), deer flies, horse flies, and water bugs (Lethocerus spp. ). For first aid treatment of a spider bite, wash the bite, and use ice, ice water or cold compresses to reduce swelling and discomfort. Bites or stings from a variety of arthropods can result in an itching wound. Rather than scratching, if necessary try to relieve the itch with medication. Scratching can break the skin and introduce bacterial infection, which you or even a physician may mistake for an arachnid bite. If you receive a bite that causes an unusual or severe reaction, contact a physician. If you catch the critter in the act, save it for identification, preserve it (or whatever parts of it remain), and take it to your county UC Cooperative Extension office. If no one there can identify it, ask that it be forwarded to a qualified arachnologist.   WARNING ON THE USE OF PESTICIDES REFERENCES Hedges SA, Vetter RS. 2012. Pest Control Technology: Field Guide for the Management of Urban Spiders 2nd Ed. Cleveland: GIE Media. O’Connor-Marer P. 2006. Residential, Industrial, and Institutional Pest Control. UCANR Publ. 3334. Oakland, CA. Vetter RS. 2015. Pest Notes: Hobo Spiders. UC ANR Publ. 7488. Oakland, CA. Vetter RS. 2015. The Brown Recluse Spider. Cornell University Press. Ithaca, NY. Vetter RS. 2017. Pest Notes: Widow Spiders and Their Relatives. UC ANR Publ. 74149. Oakland, CA. Vetter RS. 2018. Pest Notes: Brown Recluse and Other Recluse Spiders. UC ANR Publ. 7468. Oakland, CA. Vetter RS, Isbister GK, Bush SP, Boutin LJ. 2006. Verified bites by yellow sac spiders (genus Cheiracanthium) in the United States and Australia: Where is the necrosis? Amer. J. Trop. Med. Hyg. 74 (6): 1043-1048. Vetter RS, Ubick D. 2014. Pest Notes: Zoropsis spinimana, A Mediterranean Spider In California. UC ANR Publ. 74143. Oakland, CA. PUBLICATION INFORMATION Pest Notes: Spiders UC ANR Publication 7442         AUTHOR: Richard S. Vetter, Entomology, UC Riverside Originally compiled from Barr BA et al. 1984. Spiders. UC ANR Leaflet 2531. Oakland, CA. Out of print. Technical Editor: K Windbiel-Rojas Editor: B Messenger-Sikes Produced by University of California Statewide IPM Program PDF: To display a PDF document, you may need to use a PDF reader. Top of page

The most poisonous spiders in the world if the individual is not poisonous. The fear of spiders is one of the most common phobias in the world, which is quite difficult to deal with. But among people there are also extreme sportsmen who not only have spiders at home as pets, but also experience spider bites on their bodies in order to tell about their feelings later.

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There are a huge number of species of poisonous and dangerous spiders on the planet. Most people think that the Black Widow is the most venomous spider, but this is actually not the case. In this article, you can learn about the most poisonous spiders that inhabit the world. So let’s go!

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1. The first place among the most poisonous spiders on Earth is taken by the Brazilian wandering spider. The second name of this species is “Brazilian wandering spider”, but you can find the name “banana spider”, because. one of the favorite places of this species are banana palms.

Although its name does not cause concern, but its poison is extremely toxic and 10 years ago it was included in the Guinness Book of Records, recognizing it as the most dangerous among all types of poisonous spiders. The danger lies not only in the toxicity of the poison, but also in the extremely painful sensations experienced by the victim. In most cases, death occurs as a result of suffocation, which may be accompanied by the failure of some organs, including the lungs and heart, as well as muscle atrophy.

The Brazilian wandering spider measures about 15 centimeters and is considered one of the largest of all spider species. They are most often found in the South American tropics. Spiders of this species are perfectly camouflaged, including banana leaves. They can follow their prey for a long time, after which they suddenly attack an unarmed victim.

Brazilian wandering spiders like to hunt at night, and during the day they can hide in various inconspicuous places and crevices. Representatives of this species of spiders attack not only during the hunt, but also when they feel the danger. They stand up and never back down, even if they realize a small chance of victory, which makes them one of the most dangerous members of the spider species. Humans also suffer from the bites of the Brazilian wandering spider, but such bites are more likely to occur through negligence.

Banana spider venom contains the dangerous neurotoxin PhTx3, which has a number of useful properties and is therefore used in medicine. Small insects and rodents die from a bite almost instantly, while larger animals or snakes can live for about 10-15 minutes.

2. Black widow or Karakurt

This species of spider, although not ranked among the most toxic, is one of the most famous species among arthropods. There are many different myths and legends about the Black Widow, some of which have no real justification. It is generally accepted that a widow’s bite will lead to death in any case, but in reality this is far from the case. Although the sensation and pain of a Black Widow bite can hardly be called pleasant, there are not many cases of human deaths from meeting with this species.

Spider experts note that black widow venom is extremely toxic and much stronger than rattlesnake venom. If the bite of males of this species does not pose a threat to humans, then the bites of the female Black Widow should be feared. This type of spider was discovered in the early 19th century by Charles Atanas Walkenaer. On the underside of the body of females there is a rather unusual pattern that looks like an hourglass.

The size of the “Black Widow” can hardly be called impressive and rarely exceeds 2 centimeters, but the impressive venom glands and the toxicity of the poison can cause death in animals, including quite large ones. Spiders of this species live on almost all continents of the world, with the exception of particularly cold regions of the planet. There are more than 30 varieties of this species, and most of them are on the American continent.

The Black Widow is nocturnal and feeds mostly on insects, lizards, mice, snakes and scorpions. Experts in the study of spiders note that the Black Widow’s web is the strongest of the webs of all spiders. The web is so sticky that there is practically no chance for the victim to get out of it. Black Widow’s enemies include praying mantises, birds, and some species of wasps.

3. Chilean hermit spider

The next species among the most dangerous and poisonous spiders in the world is the Chilean hermit spider, whose bite not only causes extremely painful sensations and severe burning, but the poison can cause cell necrosis and skin death. About 10 out of a hundred people die from the poison of this species of hermit spiders, and some of the victims undergo a long rehabilitation chicken from tissue necrosis.

This species can be about 4 centimeters in size and is often found around South America and some European countries. The favorite places of the Chilean hermit spider are abandoned and secluded places. Attacks on people happen by accident, when the Chilean recluse spider can get under a person’s clothes and bite him. The bite is often compared to a severe burn, such as from a smoldering cigarette.

4. Six-eyed sand spider

The six-eyed sand spider is often found in the desert areas of the African continent and South America. The closest relatives include hermit spiders that live in most parts of the planet. There are about six species of six-eyed sand spiders that are most commonly found in sand, rock ledges, and near ant colonies.

The peculiarity of the venom of the six-eyed sand spider is that there is no effective treatment for it. An interesting feature is the life expectancy of representatives of this species, which is almost four times longer than that of other types of spiders. As food, six-eyed sand spiders use some insects and scorpions, which they capture with their legs, and then inject a toxin into the blood of the victim.

Six-eyed sand spiders can go without water and food for a long time, hiding in the sand. The strong venom of these spiders can cause rupture of red blood cells and tissue necrosis, as well as rupture of blood vessels, so the victim can die from blood loss. There are quite a few confirmed cases of attacks by six-eyed sand spiders on humans, but it is recommended to avoid meeting with this species.

5. Redback spider or Australian widow

Spiders of the species Latrodectus hasselti are the most common in Australia and their appearance consists of a black body color and a red stripe that is present on the back of the spiders. The web is particularly durable, and the poison can cause suffocation in the victim, and the poison itself is classified as nerve paralytic.

The size of the redback spider or Australian widow is from 0. 4 to 1 centimeter, and the habitat is not only dry and warm places, but representatives of this species are often found in cities. In the past, there was no effective antidote against the toxin of these spiders, so there have been fatal cases among people, but recently there have been none.

Also, only the toxin of females is dangerous to humans, which can attack if they are touched. But if the bite of the Australian widow does not cause death in a person, then acute pain and a number of side effects are still guaranteed, such as muscle spasms, nausea, pain in the abdomen. When bitten, it is recommended to apply ice or a cold compress.

6. Northern leucoweb spider

Most often, the Northern leucoweb spider is found in Australia – a country that literally teems with various poisonous creatures. The size of adults does not exceed eight centimeters, but the poison is extremely toxic. If earlier these spiders were found only in Sydney, now the population has spread to other parts of Australia.

The favorite habitats of this spider species are deep burrows, flower pots, doorways and tree trunks. In addition, northern leucoweb spiders often end up in the pools of Australians and people who do not notice the danger become victims. Under water, these spiders can be up to 24 hours without access to oxygen, so people often do not notice individuals that are at the bottom of the pool and attack in case of danger.

The bite of the northern leucoweb spider is not only painful, but can also lead to the death of a person, especially children. If you do not enter the antidote, then death can occur within 15-20 minutes after the bite. As the main symptoms and side effects from the bite of this spider, numbness of the limbs, tongue and lips, the appearance of shortness of breath, and coma are noted. Interestingly, the bites of the northern leucoweb spider are practically unable to cause damage to dogs and cats that have immunity in the blood.

7. Brown recluse

We have already talked about the Chilean recluse above, but how is it different from the brown recluse? The victim practically does not feel pain when bitten, but after a while a severe wound appears at the site of the bite, which can heal for several years. The venom of this spider can lead to the death of not only animals and insects, but also humans, and several cases of death among humans have been reported.

The Brown Recluse is rarely the first to attack, but if it senses danger, it will defend itself. Most often this species is found in Mexico and in the south of America. Brown recluse spiders are found in people’s homes and can crawl into beds, resulting in accidental bites. Some people confuse this species with harmless haymaker spiders, so they are not even aware of the danger.

8. Sydney leucocytopenic (funnel) spider

An extremely dangerous type of spider, and its venom can kill a person. In the first minutes after the bite, salivation increases and tears may begin, blood pressure rises, muscle twitching and severe shortness of breath are possible. If the bitten person is not provided with medical assistance as soon as possible, then death can occur from suffocation 30-40 minutes after the bite.

In the early 1980s, a vaccine against the venom of this species of spider appeared, after which not a single case with a fatal outcome among people was registered. The name of the spider speaks of its habitat and is found only in Australia, but if the species was previously found in Sydney, now the population has spread throughout eastern Australia.

The spider’s web is cone-shaped, hence its second name, the Sydney funnel-web spider. Interestingly, the poison is capable of harming primates, humans, and some insects, but is practically harmless for other animals.

9. Brown Widow

Another species of spider belonging to the Latrodectus geometricus family. Representatives of brown widows attack extremely rarely and some consider these spiders to be shy. If the attack and bite of the spider were provoked, then an insignificant part of the poison enters the blood of the victim, which rarely poses a real threat. Toxins can leave the human body within 24 hours even without special preparations.

The appearance of the brown widow is very similar to that of the black widow. This species has an hourglass-like pattern on its back, and black stripes on its paws. The brown widow’s favorite habitat is a warm climate, so they are common in Asia, the USA and South America, Africa and Australia.

10. Wolf spider

The appearance of the wolf spider is quite impressive and it inspires fear, but in fact, the spider rarely attacks a person and is not capable of causing significant harm to people from a bite. A slight burning sensation and pain from the bite is all that can happen if the wolf spider toxin enters the human blood.

About 2.5 thousand species are found in the family of wolf spiders, and they can be found almost all over the world, where the climate is temperate or warm. The attack of wolf spiders on their victims comes from an ambush and this type of spider does not weave traps from the web. The hunt is mostly solitary, and the leashes are wolf-like, hence the name. Wolf spiders carry a cocoon with future offspring, and the sizes of individuals range from 1 to 3.5 centimeters.

11. Tarantula

Tarantulas are found on a large part of the planet, where the climate is humid and warm. The life expectancy of tarantulas is over 30 years, and their bites are extremely painful, although not fatal to humans. The affected area from a bite on the body for several months may acquire a yellowish color.

It is interesting that the danger of tarantula venom varies depending on the season, and most often people are attacked in order to protect their nests, and it is mainly the female who attacks. The bite of a tarantula has been compared to that of a large hornet, which can cause fever, vomiting, loss of consciousness, itching and burning. People with allergies are at risk and if they are bitten, they should immediately seek medical help.

If a tarantula bite does not pose a particular danger to a person, then there is still a risk for pets, so it is recommended to carefully examine and treat the area from them. Tarantulas can crawl into a house or make a nest near people’s dwellings, and a few dozen or hundreds of tarantulas will not be so easy to drive out.

12. Yellow-headed spider

It is quite difficult for people to meet the yellow-headed spider, although their population is found in many European countries, but spiders of this species are distinguished by their shy disposition. This species is also found in Russia, and its poison is considered quite dangerous. When bitten by this spider, pain and symptoms in humans worsen gradually.

When the venom of the yellow-headed spider enters the human bloodstream, it experiences quite severe pain, severe headache and nausea may occur. Ulcers and bite wounds on the body may not heal for a long time, even if an antidote is administered, so it is recommended to be wary of encountering these creatures.

13. Mouse spider

The name of these spiders comes from the opinion that this species burrows like mice do, but this opinion was erroneous. Mouse spiders feed not only on mice, but also on their relatives from other species, and scorpions, centipedes and wasps are natural enemies for them.

Mouse spider venom is dangerous not only for insects and animals, but also for humans. When bitten, the victim may experience bleeding and severe pain, heart palpitations and tingling in the affected area, but there have been no fatal cases among people from the poison of this type of spider.

14. Hairy spider

Just looking at a hairy spider gives people a feeling of fear and disgust, but it is recommended to avoid encounters with this species because of its poison, which is extremely toxic. Although recently, some people have begun to breed hairy spiders at home, considering them to be quite unusual and cute creatures.

15. Baboon spider This type of spider prefers to hide deep underground and can be found most often in Tanzania, Kenya and Uganda. They belong to one of the most dangerous species, but for a person the bite will not be fatal. If the poison enters the bloodstream, severe vomiting, pallor and a feeling of weakness can begin.

16. Argiope Brünnich or spider – wasp

We complete our top list of dangerous and poisonous spiders of the planet with the view of Argiope Brünnich or spider – wasp.