What is it about spiders that cause so many people to recoil in terror? Perhaps it’s the eight hairy legs. Or maybe it’s those beady little eyes. Just as likely, it’s a symptom of our natural fear of the unknown. Few people can tell the difference between poisonous (or rather, venomous) and harmless spiders. So, as a defense mechanism, they assume all spiders are dangerous.

The truth is that of the 3000+ spider species in North America, there are really only two kinds people need to worry about…and they’re fairly easy to identify if you know what you’re looking for.

The Black Widow

Black widow spiders can be found anywhere in the United States, especially in western and southern states – including Florida. The female black widow has a distinctive look. As suggested by the name, they have shiny black bodies. The undersides of their abdomens feature a red hourglass-shaped mark. There’s no need to look that far, however, as any shiny black spider you see can safely be assumed to be a female black widow.

Male black widow spiders look completely different from females. They’re thin and usually brown or gray. Fear not, the males are also far less venomous than the females, so they’re no danger to people.

Black widows are likely to be found around wood piles and most often make their way into homes by being carried in along with firewood. They can certainly live inside the home as well as long as they find a food source such as flies, woodlice or other spiders.

The female black widow’s neurotoxic bite causes immediate pain that starts at the site of the bite and then spreads throughout the body.

The Brown Recluse

The brown recluse is predominantly found in the Midwestern and Southern United States. Contrary to common belief, you’re unlikely to find brown recluse spiders in Florida. They simply can’t survive or reproduce here. Much of their legend in the state is based on misdiagnoses.

While the go-to means of identifying the brown recluse is by the dark brown violin-shaped mark that starts at the head and extends down the abdomen, this is not always effective. Other species of spiders have similar markings and some brown recluses don’t develop the violin pattern at all. The best way to identify a brown recluse is an unattractive option for non-spider-lovers. You have to count their eyes. While most spiders have eight, the brown recluse has just six. Of course, you’ll have to get pretty close to count. While you’re there, you may also notice their legs are smooth.

The brown recluse is named for its secretive nature. They would rather not encounter humans at all. Brown recluses prefer to hide in quiet, warm, dark places and generally only bite when they feel trapped. Unfortunately, sometimes the warm, dark places they choose for homes are people’s shoes or boxes. When people reach into those areas, they get bit.

A bite from a brown recluse can be quite severe. They can cause necrosis, an infection that may cause parts of the body to die, turn black and fall off.

While black widows and brown recluses are the only North American species considered dangerously poisonous to humans, many other spiders have potential to bite if threatened and it’s possible for people to have allergic reactions to any kind of bite. Pets, children and the elderly are especially at risk. Don’t hesitate to seek medical treatment if you suspect you’ve been bitten and you experience ongoing pain or become ill.

A Note on the Use of Poisonous Versus Venomous

Many people think these words have the same meaning, but in fact, they do not. A poison is a substance that causes harm by being ingested or contacted. A venom, on the other hand, is a substance that is harmful when injected into an organism. For example, a spider or snake injects a harmful substance into its prey with its bite, thereby making that substance a venom and these creatures venomous. The blister beetle secretes a harmful substance that irritates the skin on contact and has been known to be lethal when consumed by livestock. This substance would be considered a poison and the blister beetle a poisonous insect.