Poisonous Spiders in Washington State | Identification and Risk

Most spiders are poisonous to some extent but very few contain the venom necessary to be a genuine threat to humans. In Washington state, only two spiders are of any real medical significance, the black widow and the yellow sac spiders. They are really not aggressive and bites are a rare occurrence happening only when the spider feels trapped or is unexpectedly disturbed. Spiders are, of course, renowned for their ominous presence and alien appearance. Often wrongly categorized as insects, spiders have eight legs and this makes them arachnids. 

Most Venomous Spiders in Washington State

There are thousands of spider species in the world, some are part of our everyday life and others we may only encounter via media. In Washington state, there are really only a handful of spiders which you should be aware of if you are concerned about venomous bites. Even these, remember, are unlikely to attack unless provoked, trapped, or disturbed. 

Yellow-sac spider

Scientific name: Cheiracanthium

Yellow-sac spider
A yellow-sac spider
Author: Joel Mills  CC-BY-3.0

The yellow-sac spider can be found walking about on foliage, under leaf litter, stones, boards, on buildings, and under the window sills and siding. They also like to hide in the corners of walls and ceilings within homes, barns, and basements.  The yellow sac spider in fact accounts for more human bites than any other type of spider. Humans are most likely to experience venomous bites from the yellow sac spider outdoors while gardening in the summer. Even though small in size, they have been observed crawling across the human skin surface and biting without provocation. Fortunately, most bites are relatively painless and do not result in any serious medical conditions. It is still advised to seek medical attention if you suspect you’ve been a victim of a yellow sac bite.

Black widow spider

Scientific name: Latrodectus mactans

Black widow spider
A black widow spider
Author: Camazine  CC-BY-3.0

Black widow spiders like to hide in the dark corners of your home. They need to feel safe and so prefer woodpiles, basements, cluttered spaces, and rubble. Though the black widow’s bite feels like a pinprick to most people, their toxin contains a chemical called alpha-latrotoxin that swiftly overwhelms nerve cells, causing swelling and intense pain. The effects of a bite by a member of this genus depend on the species, but effects can include nausea, profuse sweating, severe pain in the abdomen and back, muscle aches, hypertension, and paralysis of the diaphragm, which can cause difficulty in breathing. As you can see, these bites are potentially dangerous so do seek medical attention if you are affected. 

Hobo spiders

Scientific name: Eratigena agrestis

Hobo spiders
A hobo spider
Author: Julian Lino-Wiseman CC-BY-SA-3.0

The hobo spider is distributed throughout Europe to Central Asia and is also found in North America

Because they are not expert climbers, they are rarely found above ground level. Instead, they prefer dark, moist areas and are most often found in basements, window wells, and crawl spaces. The Hobo spider has eight eyes that are arranged in two straight rows. Most other selenide spiders have eyes that are in a pattern of three rows with two eyes on top, four in the middle, and two on the bottom. 

Hobo spiders are not aggressive unless catching prey or when trapped against a person’s skin. These are the only cases in which it may bite. Hobo spiders would rather run away than be involved in a confrontation. Their bite is almost painless, and it may feel like nothing more than a pinprick therefore many people do not even notice they have been bitten.

Common Spiders Found In Washington State

There are several species of spider native to Washington State but there are three that you are very likely to find around your home. These are the common house spider, the barn funnel weaver, and the wolf spider. Although they can look frightening, spiders are not aggressive creatures and are generally looking for somewhere to retreat from the rain or predators. You may find the webs and abandoned webs (cobwebs) aesthetically displeasing in your home or garage, but spiders are actually a crucial element in the world’s ecosystem. They help crops by controlling the insect populations and have their own part to play in the environmental food chain. 

Barn Funnel Weaver

Scientific name: Tegenaria domestic

Barn Funnel Weaver
A barn funnel weaver spider
Author: Judy Gallagher CC-BY-2.0

Barn funnel weaver spiders are frequently found in places like barns and sheds, cluttered basements, and crawl spaces inhabited by small crawling insect prey. If you are less than enamored with the prospect of stumbling upon this long-legged visitor, it might be a good reason to make sure that the pile of old boxes is cleared away and any dark corners are uncluttered. 

This species is not venomous for humans, and they very seldom bite. In the rare instances that they do,  the bite is painless and very unlikely to break the skin. If a barn funnel weaver spider’s web is attacked or somewhat dismantled, it will attempt to either leave the area or huddle its body into a ball against the closest stable object. 

Wolf Spiders

Scientific name: Lycosidae

Wolf Spiders
 A wolf spider
Author: Phillip N. Cohen  CC-BY-2.0

Wolf spiders are one of the most common spider species in the world. They do not build webs and instead, build burrows in the soil or crevices in trees and rocks. Human interaction is most likely to occur in humid basements, garages, yards, and sheds. Another place to look out for them is on window sills because this is one of their prime hunting grounds.

Wolf spiders look imposing but really, they pose very little threat to humans. They seldom bite and when they do, it will generally leave no more than a red mark with perhaps a little irritation. Environmentally crucial, wolf spiders are even sometimes classed as beneficial by experts as they help control the predatory pest populations on farms. 

Common House

Scientific name: Parasteatoda tepidariorum

Common House
 A common house spider
Author: David Short CC-BY-2.0

The common house spider likes quiet, undisturbed places which can provide them with potential prey and some moisture. Although they do not need much water themselves, the presence of moisture will attract the insects in which they are interested! Basements, garages, and behind bookcases are great hiding places for this ubiquitous visitor. 

Common house spiders do possess venom in their fangs = this is how they paralyze their prey however, the amount of venom is so tiny in comparison to us that a serious reaction in a creature as large as a human is extremely rare and generally due to an allergic reaction. If you think you have received a bite, do seek medical advice in case a pre-existing allergy is aggravating something which for most will be of little or no consequence.  A very un-aggressive spider, they will actually feign death if they really feel under attack. 

Symptoms of Envenomation

In general, a spider bite looks like any other type of insect bite — a red, inflamed, often irritated bump on the skin — in fact, you may not even realize you’ve received one. Harmless spider bites usually don’t produce any more symptoms than this. It is a fairly regular occurrence that bites from other insects are misdiagnosed as spider bites. If you do experience a venomous bite from a spider, it may feel as slight as a pinprick. The first signs are likely to be minimal, red marks with some swelling. Within an hour, the pain may increase and spread to your back, belly, and chest. Your abdomen may feel stiff and you may experience intense perspiration.  In even more serious cases, you can have respiratory problems, along with a fast heart rate, nausea, and vomiting. The area around the bite may continue to get redder and more angry and inflamed.

Why not have a read of Spiders in Missouri | Identification, and Risk

First Aid for Spider Bite Victims

If someone shows signs of a severe allergic reaction from a spider bite, help them get emergency medical attention and follow the steps below:

Cleanse the wound site with mild soap and water. Then, if you have any antibiotic lotion, apply this three times a day = this will minimize potential infection. Apply a cool compress over the bite for 15 minutes each hour. Use a clean cloth dampened with water or filled with ice. Avoid administering a tourniquet and check whether the victim has any severe allergies or uses an EpiPen. You may apply a baking soda pack or calamine lotion (calamine is an antihistamine). These steps should help manage the situation until professional medical advice is accessible.