Harmless And Poisonous Spiders In Pennsylvania

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There are many different spiders in Pennsylvania, and most of them are harmless. Let us find out which are the harmless poisonous spiders in Pennsylvania. However, a few species can be dangerous if they bite you. 

It is important to identify the spiders in your area so you can avoid being bitten by a harmful one. Knowing what to find will help you stay safe from these eight-legged creatures.

The black widow and the brown recluse are Pennsylvania’s most common poisonous spiders. The black widow is identifiable by its shiny, black body with a red hourglass on its underside. The brown recluse is identifiable by its head’s violin-shaped marking and light brown color.

Are Spiders Poisonous?

Some spider bites have no significant effect on humans. A small number of spiders can be potentially harmful to humans, but most are not.

To protect yourself from any harm is to learn how to identify the harmless spiders in your area and know what to do if you encounter a harmful spider.

Harmless poisonous spiders in Pennsylvania

Spiders avoid biting humans unless they feel trapped and cannot escape. Most spider bites occur when someone accidentally steps on a spider. Even if a bite does happen, the venom of most North American spiders is harmless to humans.

Common species of spiders In Pennsylvania

There are around 3,000 species of spiders in the United States. While most of these spiders are harmless, a handful can be medically important. The jumping spider is found in most houses.

The other two spiders we hear most about are the brown recluse and the black widow. Pennsylvania spiders can cause serious injury, so it is important to be able to identify them.

Brown recluse spiders are not indigenous to Pennsylvania; they can still be a problem if shipped from other states.

Jumping Spider which is considered to be harmless

These spiders can cause serious injuries if they bite someone, so people should be especially careful when these spiders are active during the fall and winter months.

Harmless Poisonous Spiders in Pennsylvania

There are only two poisonous spiders in Pennsylvania- the Southern Black Widow and the Northern Black Widow.

These are very similar in appearance, and both are highly venomous. However, many harmless spiders in Pennsylvania look very similar to these poisonous spiders. 

Types of Spiders

Finally, The types of spiders given below are the spiders to be wary of. While these spiders, like most spiders, will leave you alone.

At the same time, others will bite if they feel threatened. These types of spiders can bite with very dangerous bites, which can be fatal if not treated.

Black Widow

The Black Widow is a poisonous spider found in Pennsylvania. They have highly toxic venom which can be fatal to small children if untreated. Though their bites are not always deadly, they should still be avoided as much as possible.

Black Widow in the wild

The Black Widow spider prefers dimly lit locations, dark corners in a basement, closets, and cluttered areas.

Black widow range map

The black widow spider is the most infamous and poisonous spider in Pennsylvania. These spiders are typically identified by their shiny black color and an hourglass-shaped red mark on their abdomens.

Females are 1/4 to 3/8 inches long, while males are only half the size of females but have longer legs and more bristles on their hind legs, which they use to cover prey with silk once it has been trapped.

However, they are not aggressive and will only bite humans if they feel threatened. Male black widows are half the size of females but have longer legs and bristles on their hind legs which they use to cover prey with silk once it has been trapped.

Black widows prefer dimly lit locations, dark corners in a basement, closets, and cluttered areas.

Black widow prefers to live in dimly lit locations, such as dark corners of basements, closets, and cluttered areas.

During mating season, the male comes to the female’s web and destroys it by reducing her pheromones while they are in the home. This makes her webs less attractive to other males and increases his chances of mate with her.

Long-legged Sac Spider

The long-legged sac spider is a pale yellow or even cream-colored spider with a dark brown mouth. Sac spiders can be found under leaves, boards, stones, windowsills, under house siding, in corners where the walls meet the ceilings, and so on.

Long legged tree spider

In short, these spiders are pretty much everywhere, and they’re one of the most common poisonous spiders in Pennsylvania. They’re active hunters, and they go out searching for their victims rather than waiting for their prey to come to them.

Consequently, since they’re mainly venturing out at night, this is when the majority of bites on humans will end up happening since the vast majority of people are sleeping and they’re leaving shoes and clothing unused.

 Black-Footed Yellow Sac Spider

The Black-footed Yellow Sac Spider is a venomous spider found in the United States. It is pale yellow-beige with dark brown markings on its palps, jaws, and the ends of its feet.

They are typically around 1/2 inch long and can be found in most parts of the country.

Yellow sac black footed spider searching for the prey

The black-footed yellow sac spider is a common household pest in Pennsylvania. It gets its name from its appearance (its abdomen resembles a sac).

The bite begins with a bit of pain followed by itching and swelling; symptoms from the bite typically go away within 7-10 days.

Brown recluse

The brown recluse house spider is poisonous and is found in Pennsylvania. They have dark skin and are typically found outdoors in woodpiles and debris and indoors in closets, attics, and crawlspaces.

Insect bite symptoms include a burning sensation at the bite site, restlessness, fever, and difficulty sleeping.

Brown Recluse Spider in the house

Though the vast majority of spiders are generally harmless, they can still give most people the creeps. And because we want to avoid them in our homes, if we can help it, we need to be able to identify those that may be harmful. The brown recluse is one such spider.

What is the most common spider in Pennsylvania?

The black widow spiders are common in Pennsylvania. These insects are easily identified by their shiny black bodies and red hourglass shape on their abdomen.

They are venomous and can be harmful if bitten, but are not typically aggressive towards humans.

However, many harmless spiders live in the state. They are typically found under rocks and in the dark, undisturbed areas such as woodpiles or the corners of a garage.

What Happens to Spiders in the Winter?

Spiders go through a diapause process in the winter, which causes them to slow down. There is a wide variety of spiders here in Pennsylvania. There’s no getting rid of them unless the temperatures drop below freezing for an extended period.

I know it’s a common misconception that winter comes every year, and all the insects die off due to the cold temperatures. There would be no problem with insects when spring arrived and the weather warmed up again.

What to do when a spider bites you

Spiders only bite humans if they feel threatened. Most spiders are harmless and will not cause any harm. If a spider bites you, it is important to identify the spider to take the necessary precautions.

When bitten by a poisonous spider, the side effects can be very unpleasant. Most spiders have venom that is harmful to humans, and it’s important to know what to do if you’re bitten. If you are a bit, try to identify the spider and seek medical attention.


While there are many poisonous spiders in Pennsylvania, the only one that should be worried about is the Black Widow spider. This spider is easily identified by its black body and red hourglass on the underside of its abdomen.

If you come across a spider that you are not sure is a Black Widow, it is best to contact a professional for identification.

Overall, the black widow spider is not harmful to humans. Their bites are mostly non-fatal. However, it is always important to be cautious when encountering any spider.

About the author

A biotechnologist by profession and a passionate pest researcher. I have been one of those people who used to run away from cockroaches and rats due to their pesky features, but then we all get that turn in life when we have to face something.