Updated: May 25
I think it’s safe to say that many (most?) human beings worldwide are repulsed – and in many cases terrified – by spiders. Very few people actually suffer from arachnophobia, which is classified as an identifiable phobia, but the aversion to these eight-legged arthropods is nearly universal. Exactly how, and why, remains a mystery. Observers have suggested a number of causes, one being an evolutionary response, something “hard-wired as an ancestral survival technique”. Other possible explanations include cultural or religious beliefs, and genetic or family influences.
That said, it’s important that we emphasize the enormous – nay, irreplaceable – role that spiders play in our common ecosystem. Like bees, birds, and numerous other benign creatures, spiders are an integral part of our world.
“Spiders are abundant and widespread and, best of all, a natural controller of insect pests. [They] . . . are beneficial predators and serve a significant role in keeping populations of many insect pests in check. Spiders are . . . [perhaps] the most important biological control of pests in and around homes, yards, gardens and crops.”
What’s more, spiders are generally small and present no threat to humans. In fact, there are only four species native to the US whose bites can trigger severe responses in humans.
However, the fact remains that some spider species may be less welcome in your home. So, to help you know the difference here is some information about many of the most common types of spiders that you may meet, and details about when they pose a problem and when they can be ignored (if not coddled and pet). Plus, get details about how to get rid of spiders if needed.
Dealing with Spiders
If you’re like me, I don’t kill spiders – even the ‘nasty’ ones. I try to keep in mind that “killing a spider doesn’t just cost the arachnid its life; it may take an important predator out of your home.”
That’s not to say that I allow the latter to set up shop in my home. I prefer to trap the unwelcome varieties (usually under a glass, so I can see what it’s doing) and then free them in the garden, as far away from the house as I can.
However, if you cannot bring yourself to even approach one of these unpleasant creatures you can always resort to an effective insecticide, such as Sterifab®.
Sterifab is the only EPA-registered product that works simultaneously as a virucide, disinfectant and insecticide. With just a few sprays, Sterifab will quickly kill bed bugs, fleas, ticks, mites, viruses, mold, mildew and more. Oh yes, and spiders! Plus, it disinfects viruses and bacteria and gets rid of pathogenic odors.
Another plus: Sterifab is non-residual! It dries in 15-20 minutes − with no trace – and it’s one of the only products labeled for use on mattresses and upholstered furniture.
You can learn more about the many uses of Sterifab here:
So, which spiders do you save from death and which do you eradicate? Here is my list of those spiders you can happily allow into the house:
Cellar Spiders (aka ‘Daddy Long Legs’)
Cellar spiders are harmless – and very useful to have around. They can range in color from grey or tan to white. But the thing that is most notable about them is their long, delicate legs and very small abdomen. Although they are often mistaken for Harvestmen they are quite different. Harvestmen are unable to spin webs since they lack silk glands. And they don’t possess venom glands, as do most spiders.
You can find them in virtually any home − especially garages, basements, and cellars – usually hanging belly-up in corners. They prey upon other insects, including some much larger than themselves, such as crane flies and wolf spiders.
American House Spiders
Unfairly maligned, and often the object of (truly) irrational fear, common American House spiders are innocuous and utterly harmless – unless you are a housefly, mosquito, silverfish, tick, bed bug, beetle, fruit fly, and any number of other insect pests.
American house spiders have rounded abdomens and tend to be small – roughly the size of a nickel. They are often grey in color, although they might possess white markings of one kind or another. And, like most spiders, they prefer to live in secluded, dark, out-of-the-way places, such as attics, basements, hard-to-reach corners, garages and anywhere there is a regular supply of food, especially flies!
Orb Weaver Spiders
Orb Weaver spiders, of which there are some 3,122 species in 172 genera, can be found throughout the world. They are generally harmless and won’t bite, unless they are attacked. The good news is, they’ll usually flee rather than fight. They are not the easiest of spiders to identify, since they can range in color from gray to dark brown and can have smooth or spiny abdomens.
However, they do weave very large webs, which they tear down and build each day. Look for their webs on porches, decks and other parts of a house’s exterior, such as light fixtures. Orb weavers are particularly helpful when it comes to controlling the bugs that like to congregate around lights.
Jumping spiders – not to be confused with those little black crickets that like to live in basements – come in a variety of species (300 in all), which all look very different. In fact, they can range in appearance from black with markings not unlike a zebra to truly iridescent. However, what really sets them apart from their arachnid cousins are their very large set of eyes, right in the middle of their foreheads. Bottom line: They are truly fearsome to behold!
What’s more, they can be found just about anywhere in your house; they have no preference vis a vis living quarters. Attics, basements, walls, in the (dry) eaves of the house, in trees; you name it, Jumping Spiders will live there. Fortunately for us, they are truly harmless and very useful when it comes to ridding a home of other, unwanted pests.
It should come as no surprise that there are many, many dangerous spiders in the world, although for our purposes we are focusing on the six species you’re most likely to encounter in the US. Fortunately, we don’t have to deal with the Sydney Funnel Web spider, the Chinese Bird Tarantula, the Mouse spider or the Brazilian Wandering spider, to name but a few of the deadlier spider species.
So, here are the six spiders you should avoid at all costs – and remove from your house!
Black Widow Spiders
Black Widows are fairly easy to spot, with their shiny black color and distinctive red hourglass-shaped marking underneath the abdomen. Some may even have markings on their backs, although this is uncommon. And some spiders are often mistaken for their deadlier cousins, such as the so-called False Black Widow or Steatoda grossa, which is actually a chocolate brown color and is slightly smaller than the Black Widow – and Domestic House spiders like the Barn Funnel Weaver.
And yes, Black Widow spiders are poisonous. However, out of the 2,000-plus bites that are reported each year, there have been no fatalities in the US for over 50 years. Still, if you are bitten by one of these spiders go immediately to your local ER. Look out for them in garages, mailboxes, bird feeders and in tall grass and under rocks, especially if you live in the Southwest.
Red-Legged Widow Spiders
Red-Legged Widow spiders are actually quite rare and found only in sand-pine scrub in central and south Florida. However, while they are small − with red legs, of course – their venom is poisonous to humans. Keep in mind, however, that Red Widow Spiders are listed as a Threatened Species, so be careful how you handle them!
Brown Recluse Spiders
Of all the spiders commonly found in our homes, the Brown Recluse spider is one that you should always avoid. They are usually found in dark, dingy places, hiding under ledges, stairs, rafters, and the like. In fact their aversion to sunlight and preference for solitude is why they’re called ‘Recluse” spiders in the first place.
While they are small, these brown spiders sport a distinctive violin-shaped marking on their heads and back, as well as angular legs. But give these creatures a wide berth, since a bite from one of them can be quite serious, causing necrotizing injuries, meaning the venom from a Brown Recluse destroys the tissue at the bite site. If you are bitten, seek medical help right away.
Grass spiders, as their name suggests, prefer to spend their time outside, but they’re not averse to setting up shop in a house, particularly in and around the foundations. Entomologists hypothesize that this preference has to do with the availability of (possible) female mates, but the jury is out on that one. While they are often mistaken for Brown Recluse spiders, you can tell them apart by the Grass Spiders’ tell-tale long spinnerets.
As entomologists at Penn State point out, “These spiders are extremely fast and shy. Consequently, very few people are bitten. [But] . . . their bites have been reported to cause pain, swelling, redness, and itching, with the duration of symptoms ranging from one to ten days but without serious consequences.”
Wolf spiders are usually brown, grey, black or tan, with dark markings and can range in size from half an inch to an inch. And they do look very fearsome, especially since they sport two medium eyes on the side of their heads, and two large eyes above a row of small eyes! However, they are not as dangerous as they look, at least not to humans anyway. Alas, the same cannot be said for their prey, which they run down and attack in a really quiet athletic fashion. No webs for these spiders.
Experts at Penn State say that these spiders will only bite if they feel threatened, and their venom isn’t particularly dangerous to humans. However, a bite may result in swelling or redness, but little more. It’s rare to find these spiders in a home, but not unknown.
Yellow Sac Spiders
Finally, because we have limited time and space, we come to the last of the common spiders that call the USA home: Yellow Sac spiders. These spiders are small and vary in color between pale beige and yellow, although some observers have reported specimens that have hints of green. This notwithstanding, the tips of their legs are invariably dark brown. Also noteworthy is the fact that the top part of this spider’s abdomen has a dark, v-shaped mark that runs down to its midpoint.
Like many of its cousins, Yellow Sac spiders seem to prefer dark, secluded spaces in the garden, but have been known to seek shelter indoors during the colder months. However, keep in mind that these spiders are venomous and their bites can be very painful. Untreated they can cause fever, malaise, muscle cramps and nausea.
When Reinforcements are Needed to Get Rid of Spiders!
If you are unlucky enough to suffer an infestation of spiders, you may find that locating – and eliminating – these unwanted interlopers is a problem. And the challenge is compounded if you’re dealing with one of the truly dangerous spiders discussed above. So, what should you do? Call a Pest Management Professional (PMP) − right away.
There are any number of good reasons to call in a PMP when you have a serious bug problem. For instance, as one PMP told us:
“By their very nature chemicals are dangerous-especially if they’re handled
improperly or used in ways the manufacturer did not intend. In fact,
professionals and members of the public alike should always be extremely
careful when using any kind of pesticide. Obviously, different situations,
different pest problems, call for different approaches. What works well in
one set of circumstances won’t work in another. Which is why we use a
variety of products in our work.”
A qualified (and usually certified) PMP will not only hunt down the source of your spider infestation but may well uncover other pest problems you didn’t know about! The fact is that one pest problem is usually a sign that there may be others. It’s not always the case, but a PMP will quickly tell you.
Dealing with another type of bug?
Check out the Bed Bug Blog for details about how to get rid of everything from bed bugs and scabies to ticks, lice and rodents!