Venomous Spiders of North America: How scared should you be?
Keister. Bottom. Rump. Derriere. Behind. Gluteus. The most common place for a black widow bite is on a person’s butt. Keep reading to find out how to keep your tushy safe.
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Venomous spiders often get a bad rap as the subject of many unflattering and less-than-factual rumors. But I am here to untangle the web of mysteries! Despite their spooky reputations, very few spiders in North America pose any real danger to humans- and even those that are dangerous to your undercarriage are not aggressive and unlikely to bite. Indeed, the spiders’ fearsome reputation is overblown. With some knowledge, we can better understand and coexist with these fascinating li’l friends rather than reach for the nearest shoe.
You see a spider spinning a web in the corner of your living room. It looks like a harmless li’l cobweb spider, but you’re not sure. Do you:
Squish it
Relocate it to the outside
Leave it be
Find a fly to throw at the web
It’s a spider’s world
Spiders are among the most numerous animals on the planet. With about 50,000 species worldwide, there are approximately 3 million spiders for every human on earth. Of that number, only about 100 species are considered dangerous to humans, and there is even less to fear for those living in North America. In this region, only a handful of spiders are hazardous to humans: the black widow (consisting of three species) and the brown recluse (consisting of 11 species).
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Black widows: Not so deadly queens
Black widows can be found throughout North America. They are less common in cold regions and are rare in Canada. In fact, the only US state without a record of a black widow is Alaska! (The human population is about to surge in “The Last Frontier.”) There are several species of black widows in North America- Northern, Western, and Southern.
[map of species]
All species of black widow in North America are considered dangerous. The females of these widows all have the classic black with a red hourglass coloration. They grow to be about ¼ an inch in length. These gals, including legs, can be up to an inch and a half in diameter. Males can be more challenging to distinguish. They look similar to many other spiders, as they are mostly brown. However, males are not considered dangerous to people. Since they are smaller (about half the size of a female widow), they have difficulty piercing human skin, and their venom is much less potent than their female counterpart.
Black widows prefer dark places to spin their webs. In the wild, widows find dark, damp places like rodent burrows, hollow logs, and rock crevices. Crawl spaces and wood piles are common areas where humans and widows come into contact. Another common place is outhouses. Widows make their homes inside the toilet hole, only to find themselves scared when an unsuspecting full moon makes them feel trapped, creating a poopy situation for both the spider and human.
Female widows rarely leave their web once it is established. Occasionally, they will move to warmer (aka indoor) locations in the fall to escape the impending cold. More significant movements of widows can be seen in the spring and summer when freshly hatched females will disperse from the relative safety of their mother’s web. They do this through a method called ‘ballooning.’ This involves climbing to a high location, dispensing silk to catch air currents, and being taken by the wind. While seeing many dispersing spiders can be alarming, it is important to note that juvenile black widows- which look similar to males- are rarely dangerous. Like males, they generally cannot pierce human skin. However, they contain a toxic compound- different from their venom- that can be dangerous if ingested by pets or kids.
Bite prevention, butt preservation
Black widows are dangerous, but they are not aggressive. With caution, no harmful incidents should result from human-spider interactions. (That means clean out your stinking toilet hole!) Black widows are native to North America; exterminating them from your local area could harm local habitats. A predator with such a punch likely plays a significant role in an ecosystem, even if it is poorly studied or understood. Instead, preventing them from entering your home is a better solution. Seal entry points. Ensure that spiders can’t enter through cracks in crawl spaces or attics. Always inspect pieces of potential spider habitat when you bring them into your home. For example, firewood is an excellent place for widows to hide. Give it a shake, or knock off any potential webs before toting it in.
If you spot a widow in or near your home, you can use a butterfly net or other long rod to remove her from her web, place her in a jar, and take her elsewhere. Remote locations that offer suitable habitat but a low chance of human interactions are good relocation sites. When handling a widow, it is wise to wear heavy-duty gloves, sleeves, and pants, even if you do not plan on touching her.
Safely relocate spiders and insects!
When hiking or recreating in a place with a high abundance of black widows (think southern US) wear long pants and socks to prevent bites.
If a black widow bite occurs, remember that they are rarely fatal but that you should seek medical attention. Washing the bite and keeping it elevated can prevent some of the worse symptoms of black widow venom. Bites are usually painful immediately. The venom attacks nerve endings, causing pain and muscle aches spreading from the site of the bite. Other symptoms include trouble breathing, headache, nausea and vomiting, excessive sweating, and fever. While these symptoms are scary and should be taken very seriously, keep in mind that bites can be easily treated at any medical facility.
With caution, encounters with black widows can be very educational and exciting! For example, the Flocking Team recently found a black widow in a corner of the ceiling of our bathroom. We carefully used a butterfly net to get her down and trap her in a jar. After photographing our gorgeous lady, we released her near a prairie dog town where she has hopefully made a new home. With caution and respect, we had a memorable experience! And now, we make sure to shake out our boots and double-check our firewood. (Clean your toilet holes and shake your wood.)
Take your own macro shots!
Our favorite macros for spider shots:
Brown Recluse: If it's brown, wash it down (but don’t flush them)
If you think you see a brown recluse and don’t live in the South, it’s probably NOT a recluse. Many spiders are brown and long-legged. The recluse has many look-alikes, but none of them are dangerous.
There are 11 species of brown recluse in the United States. Of those, only four are dangerous. However, they all look very similar. So, how do you tell if a spider is a brown recluse?
Build your spidey skills!
Brown recluses vary in color from tan to gray. (Which isn’t much of a variation.)
Recluses have a violin-shaped marking on their head/back, right behind their eyes. However, some young recluses do not have this mark, and some spiders of other species also have similar violin patterns. (I know, NOT very helpful)
Recluses have six eyes that come in pairs- two front and center and two on either side of the head.
Their legs are long and uniformly brown with no bands or stripes. Legs are also finely haired and do not have spines.
The abdomen of a recluse is one uniform color. If it has any pattern variation, the spider is not a recluse.
Recluses make their webs out of sight. Like widows, they prefer dark corners and are rarely seen elsewhere. Big webs with the classic Halloween-esc pattern are only made by orb weavers- harmless and friendly spiders. Cellar spiders, a recluse look-alike, frequently spin conspicuous webs in corners.
Recluses are small spiders. They do not grow bigger than ½ inch.
Similar to black widows, brown recluses are shy and rarely aggressive. This is what gives them the name ‘recluse.’ They nest in dark places like caves and wood piles. Near homes, they will also get into crawl spaces or under the eaves of a roof. They are seldom seen during the day but will be found hunting at night.
Brown recluses are native to the southern US and should be cautiously relocated if found indoors using the techniques described above in our black widow section. Brown Recluses are rarely discovered in cold places, and when they are, it is often because they are accidentally transported on human luggage or goods.
Brown recluse respite: Avoiding bites and saving your skin
As with black widows, keeping recluses out of the home involves sealing off entrance points. Since they are diminutive spiders, they may be able to squeeze through cracks under doors or in the facia of a home. Sealing these spots with expanding foam can prevent them from becoming pests.
Additionally, picking up clutter in the home will keep spiders from finding a quality nesting spot. Shaking out shoes, boots, and clothes can prevent brown recluse incidents.
Recluse bites are rare, often occurring while an individual is asleep and accidentally rolls onto the spider. (Yikes!) Typically, these bites are not immediately painful but can lead to necrotic sores. The bites usually clear up without intervention, but secondary infections are common.
Stay Calm and Keep Informed with Venomous Spiders
Spiders can be scary, no doubt about it. They seem intimidating, but with the right mindset and perspective, we can go from fearing them to appreciating some new lil friends. By making small changes and learning about their habits, humans, spiders, and their environments will stay safe and healthy.
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Photo Credits
Male Black Widow. Photo: louis/flickr.com
Ballooning Spider Webs Caught on Grass. Photo: SarahWardMedia/flickr.com
Brown Recluse on a Log. Photo: MikeKeeling/flickr.com
Brown Recluse range map. Credit: Richard S. Vetter
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