Spiders are often feared by humans and killed unnecessarily. Many people think they are all dangerous, but the truth is most spiders are harmless, and they actually help reduce the insect population. There are 500 spider species living in Oregon, and in this article we highlight some of the most common arachnids in the state and tell you which ones are actually dangerous.
10 Common Spiders in Oregon
1. Western Black Widow
Scientific Name: Latrodectus hesperus
The Western black widow is native to the western part of the United States and is the only venomous spider in Oregon whose bite is considered to be medically significant. The venomous female has a glossy black body with a large, round abdomen.
They are identified by a red hourglass-shaped mark on their underbelly. The males are brown or gray and have a small red dot on their abdomen instead of an hourglass-shaped mark.
The females can grow up to half an inch in length, and the males only grow to be about one-third that size. Western black widows are most common in Eastern Oregon but have been seen in the Southwestern and Northwestern regions of Oregon as well.
2. Hobo Spider
Scientific Name: Eratigena agrestis
The male and female hobo spiders look very similar, so they are not sexually dimorphic. The females are slightly larger than the males, and they are both brownish red in color with a herringbone pattern on their abdomens.
The hobo spider prefers to live in gardens, fields, and bushes. A hobo spider bite is unpleasant but doesn’t pose any real threat to humans unless an allergy is present.
3. Giant House Spider
Scientific Name: Eratigena atrica
The giant house spider is the largest spider in Oregon and prefers to reside where humans live. With a leg span of up to three inches, these arachnids can look intimidating but harmless to humans. This species looks similar to the hobo spider, and it may be difficult to tell them apart, but giant house spiders are bigger than hobo spiders.
4. Gray House Spider
Scientific Name: Badumna longinqua
Gray house spiders prefer living inside your home, but this shy spider is rarely seen by humans. This species ranges from dark gray to brown but gets its name from the light gray hairs on this spider’s abdomen and head.
The gray house spider can grow slightly over half an inch long and has relatively short legs. These spiders do not build multiple webs but instead spend their entire lives on one erratically built web, which can usually be found around tiny cracks and other hiding places in a home.
5. False Black Widow Spider
Scientific Name: Steatoda grossa
As the name suggests, the false black widow spider looks a lot like the true black widow spider. This species, commonly found in homes across Oregon, is around the same size as a true black widow and is primarily black.
Instead of being entirely black, the false widow has light yellow or grayish markings. The false black widow also lacks the tell-tale red hourglass on the underside of its abdomen, and its abdomen is also more oval-shaped than the true black widow.
6. Common House Spider
Scientific Name: Parasteatoda tepidariorum
American house spiders are commonly found in homes throughout Oregon. These creatures build wispy cobwebs like the typical webs you see in haunted houses around Halloween.
American house spiders can be found in windows, corners, and other undisturbed areas. They are brown with white or black speckles on their bulbous abdomens. Though commonly found in the home, these spiders are not aggressive and prefer to be left alone.
7. Triangulate Cobweb Spider
Scientific Name: Steatoda triangulosa
This small spider is commonly found around windows and lights or in dirty corners of areas with low traffic, such as garages. Triangulate cobweb spiders are covered in tiny hairs and are yellowish-orange with yellow legs. Though commonly found inside homes in Oregon, these spiders are not venomous and are not usually aggressive.
8. Yellow Sac Spider
Scientific Name: Cheiracanthium inclusum
The yellow sac spider ranges from pale yellow to yellowish green. They are small spiders, growing up to 3/8 of an inch long with a leg span of up to one inch. Instead of webs, the yellow sac spider builds silken sacs, which can be found on firewood, planters, and curled leaves.
During the colder months, they may venture inside and build sacs where a wall meets the ceiling or on windowsills. These spiders have strong fangs and can puncture a person’s skin. Though no deaths have been attributed to a yellow sac spider’s bite, their bite can be painful and may cause issues that need medical attention.
9. Cellar Spider
Scientific Name: Pholcus phalangioides
Cellar spiders are known for their small bodies and long legs. Their bodies are less than half an inch long, but their legs are up to two inches long.
They are different shades of brown, with the thorax usually a lighter shade than the abdomen. These common spiders in Oregon are found in homes and buildings, especially in cellars and basements.
10. Arrowhead Spider
Scientific Name: Verrucosa arenata
The arrowhead spider is a unique-looking member of the orbweaver family, so they build large, orb-shaped webs. These arachnids get their name from the arrow-shaped marking on the top side of their abdomen.
The abdomen itself is also arrow or triable-shaped instead of round or oval, like most other spiders. The arrowhead spider ranges in color from light brown to reddish-orange, and the arrow-shaped marking is typically white or yellow. The females can grow up to twice as large as the males, measuring up to 14 millimeters in length.