Are Spiders Dangerous to People, Pets and Property?

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Eight velvety legs and a menacing reputation. But are arachnids as dangerous as we think? Here's the lowdown on spiders and their bites.

Virtually all spiders produce some level of venom. However, of the roughly 45,000 named species of arachnids in the world, only a handful bite. And of those that do, fewer inject a concentrated poison strong enough to be life-threatening.

For the majority of household and garden-variety spiders, nips are unusual, often occurring in self-defense. They typically cause only mild reactions such as:

  • Itching or rash;
  • Pain radiating from site of bite;
  • Reddish to purplish color or blister.

More severe symptoms could include:

  • Sweating;
  • Difficulty breathing;
  • Headache, nausea and vomiting;
  • Fever and chills;
  • Anxiety or restlessness;
  • High blood pressure.

Note: If you are experiencing any of the above, seek emergency medical care.

Are Spiders Dangerous To People?

They can be.

A spider’s venom is designed to shoot insects and other small animals with poisons that paralyze them so the spider can eat them. Humans are quite a bit bigger than spiders, of course, so the damage done if they break the skin is generally minor.

And what about spiders as disease vectors? A study by the University of California, Riverside ruled out spiders as a cause of bacterial infections in humans.

All this doesn’t mean people don’t die from spider bites, but such instances are rare.

According to the Centers for Disease Control and Prevention (CDC), two kinds of poisonous spiders found in North America are dangerous to humans: The black widow and the brown recluse (a.k.a. violin spider). A stick from either of these long-legged arthropods can be painful and potentially lethal, particularly to those with allergies. Immediate medical attention is recommended.

Are Spiders Dangerous To Pets?

Spiders pose the same risk to pets as they do to humans. But since dogs and cats weigh less than most humans, a bite by a black widow or a brown recluse can be 15 times more powerful. If your pet displays symptoms such as muscle paralysis, vomiting, diarrhea and/or tremors, get them to the vet right away!

Pro Tip: If your pet eats a poisonous spider, stomach acids will probably neutralize the toxins. Keep a close eye on them for a day or two and call the vet if your pet shows signs of illness.

Do Spiders Damage Homes and Yards?

Other than spreading creepy cobwebs, spiders don’t damage structures. In the garden, spiders feast on bugs that feast on plants. They are the leading predator of insects, providing an important service to our ecosystem.

Says Ron Crawford, resident spider expert at the Burke Museum in Seattle: “If someone who was an arachnophobe could wave their magic wand and make all spiders disappear, it wouldn’t be long before all human agriculture would be impossible, and our species and most other non-insect invertebrates might very well go instinct.”

What To Do If You Have Spiders

Unlike ants and bees, who gather in colonies and work as a team to infest your home, spiders are individualists who prefer to work alone.

One of the best ways to prevent spiders from overtaking your space is to get rid of them as you see them. It sounds daunting, but the most effective way to control them is to make a preemptive strike. Remove them before they have a chance to lay eggs that will hatch into a “clutter” of spiders.

Other ways to stop spiders from encroaching on your home and property:

Toni DeBella
Toni DeBella is a freelance travel, lifestyle and digital content writer based in a medieval hill town in central Italy. Her work has been featured in such publications as Fodor's, The Telegraph, Walks of Italy, Italy Magazine, Frommers.com, Touring Bird (via [email protected]) and more. Most recently she authored the 2020 edition of DK Eyewitness Sicily travel guide. When Toni is not roaming around Europe, you'll find her tending her alley-side container garden or honing her clay-court tennis game.