Idaho is one of the states with plenty of spiders in woodlands, gardens, and even in homes.
Home to many species native to Western habitats of the US, spiders of the state may enter homes to overwinter or to look for food.
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Are There Venomous Spiders in Idaho
Western Black Widows are some of the most dangerous spiders in the state. Together with other species, the spider may lead to mild reactions such as nausea when it bites.
Most spiders in Idaho prefer not to bite unless poked, cornered, or roughly handled otherwise.
Types of Spiders in Idaho
You’re most likely to encounter one of the following species across the state.
1. Bold Jumping Spider
Bold Jumping Spiders (Phidippus audax) are a common species of black spiders that don’t build spider webbing.
A black base color is contrasted by red or yellow spots on the abdomen while blue is seen on the mouthparts of the species.
These types of spiders move around for prey but they can produce silk in certain situations.
Nursing is based on a silk-like nest while the species might also use spider webs to safely repel to the ground.
These spiders can bite when roughly handled. Pain which may last up to 48 hours is specific to its bite.
2. Zebra Jumping Spider
Zebra Jumping Spiders (Salticus scenicus) are seen around urban areas as well as in open areas. These spiders are identified by black and white coloring.
The spider grows to a maximum size of 9mm and is native to Idaho and other US states.
Zebra Jumping Spiders ambush prey such as mosquitoes.
While they don’t build spider webs, these spiders make a silk-like thread for easier movements.
Females reproduce after an initial dance mating ritual.
They lay egg sacs and exhibit protective habits similar to other jumping spiders.
3. Cat-faced Orbweaver
Cat-faced Orbweavers (Araneus genocides) are some of the most common web-building spiders in Idaho.
This species is routinely seen around homes as they tend to be attracted by light.
Spiders of this family build large spider webs near light sources because lights attract their common prey.
Mosquitoes are among the favorite prey of the species. Since they live around homes and sewers, these spiders also eat flies that live around the house such as drain flies or common house flies.
While a common sight, this species doesn’t bite as it prefers to hide from humans.
Possible bites come from rough handling but they aren’t followed by serious reactions as the species has weak venom.
4. Western Black Widow
Western Black Widows (Latrodectus hesperus) have a protein-rich venom that causes mild or severe reactions if stung.
This spider’s bite may result in nothing more than a passing itch but it may also result in headaches and even nausea.
Western Black Widows are identified by their black base color with red hourglass-like markings on the abdomen.
These spiders are known to eat a wide range of bugs and insects, as opportunistic spiders.
They can eat bees and even wasps. Beetles and ants are also a common food for the Western Black Widow.
The potent venom of the species can sometimes paralyze prey a few times larger than the spider itself.
5. Goldenrod Crab Spider
Some of the most common camouflaging spiders in Idaho are Goldenrod Crab Spiders (Misumena vatia).
As their name implies, these spiders are often seen on goldenrod where they await flies and insects.
The species has an expansive host range which also includes daisies.
Multiple types of yellow flower plants are also hosts for the spider as its yellow colors act to its camouflaging advantage.
As it spends the most time on yellow flowers, Goldenrod Crab Spiders don’t spin spider webs.
This species easily moves around for prey on flowers using its elongated pair of front legs.
6. Grass Spiders
Growing to a size of up to 19mm, the group also known as American Grass Spiders (Genus Agelenopsis) is a common sight across the state’s dense vegetation.
This species builds large spider webs to catch insects, just above the ground.
A small protective silk structure on the edge of the spider web is where this species hides in.
These spiders are known for their quick reactions. While they don’t have a sticky web, they catch most trapped insects through their quick reactions.
Most spiders of this family have grey-brown hair bodies and legs.
7. California Flattened Jumping Spider
A base black color is specific to this California spider (Platycryptus californicus). The species has a gray central dorsal section with a flattened profile that inspires its name.
Brown spots and brown marks on the legs further help differentiate the California Flattened Jumping Spider from other species common across the Western US states.
The range of this species expands further South to Arizona and West to Washington.
8. Thin-legged Wolf Spiders
These spiders (Genus Pardosa) are found both in a gray and a green undertone across the state.
Long legs are characteristic of the species. Their long legs have short bristle-like black hairs.
Thin-legged Wolf Spiders are a rapid species. They move quickly for prey instead of building spider webs.
Females of the species may sometimes be seen around gardens and next to homes carrying their egg sacs.
Both females and males may be difficult to spot as they spend almost all day hiding. Burrows tend to be their favorite nesting sites.
9. Western Lynx Spider
Western Lynx Spiders (Oxyopes scalaris) use camouflage to trap insects right on the plants they gather nectar and pollen from.
This species is good at taking the colors of the host plants it sits on.
Male Western Lynx Spiders have a base black color of the abdomen while females have a tan to brown abdomen color.
This species is considered a beneficial spider on Western US crops, including those in Idaho.
It eats many types of invasive bugs and insects, especially those in alfalfa, cotton, and soybean.
This spider is also one of the most common stink bug predators.
It has more uniform coloring compared to Striped Lynx Spiders seen in the Eastern parts of the country.
10. Northern Yellow Sac Spider
Common in homes across Idaho, the Northern Yellow Sac Spider (Cheiracanthium mildei) has an introduced status in North America.
Originating from Europe, the species is identified by its claw-like leg tips and by its pale color.
These spiders are known to bite, even if they aren’t a real threat to humans.
The highly common indoor nature of the species makes it one of the spiders with consistent bite reports in the state.
This spider may also bite in gardens since it can hide in plants or under leaves.
You may find this species around the house at the beginning of the summer and until August.
However, the species prefers to move around the house at night more than during the day.
11. Banded Garden Spider
These types of spiders (Argiope trifasciata) are a common sight in low vegetation specific to gardens, as its name implies.
A base yellow color is seen on the dorsal side of the species with white and black contrasting bands. The underside of the species can be white or yellow.
Banded Garden Spiders aren’t aggressive even if they can bite. You can get bitten by the spider if you poke it or roughly handle it.
The species is seen on spider webs of different sizes in the garden.
Female Banded Garden Spiders spend much of their time in the central part of the spider web so they can move fast to any part of the web and insect catches on.
You can find this species is very active in the second part of the summer.
12. Hobo Spider
Hobo Spiders (Eratigena agrestis) are some of the most common spiders in Idaho homes. Their common nature is subject to many myths.
Their bite isn’t lethal or medically significant to humans.
A dark brown-black abdomen with diffused patterns makes for easy species identification.
While an introduced species, the Hobo spider can have subtle geographical coloring differences.
Seen in many homes, the species can easily survive on crops and other open locations. It lays eggs in the fall which overwinter and only hatch in the spring.
You can find the species in almost all areas of the state with signification populations in neighboring states such as Washington.
13. Ground Crab Spiders
This genus of spiders (Genus Xysticus) comprises hundreds of subspecies with a similar brown or light brown look.
These spiders have legs that make them resemble small crabs.
Ground Crab Spiders don’t build spider webs as they use their dark colors to get camouflaged in vegetation and dead leaves.
A waiting tactic allows the species to grab all types of small insects, bugs, and other spiders as food.
There’s a considerable difference in the size of female Ground Crab Spiders to the size of the males.
Most females can grow to 10mmm while males grow to a maximum size of 4-5mm.
14. Western Spotted Orbweaver
This species of orbweaver spider (Neoscona oaxacensis) has a bulbous abdomen with a black-and-white pattern with a central dorsal brown band.
Its dome-shaped abdomen appears wider than the abdomen of spotted orbweavers in other regions of the world.
These spiders are seen on spider webs where they consume various flies including small moths.
Western Spotter Orbweaver eggs start to hatch as soon as temperatures start to rise at the end of the winter.
15. Barn Funnel Weaver
These types of spiders (Tegenaria domestica) are a common sight in Idaho homes. They can make it into basements but may prefer to be outside in the summer.
A brown and black body is specific to the species.
Irregular black dots and patterns are visible on its abdomen.
The species builds funnel-shaped silk weaves where they hide in face of danger.
While they can be spotted either in or around homes, Barn Funnel Weaver spiders aren’t aggressive as they prefer to hide when seeing a threat.
They hide by retreating in their funnel web.
16. Triangulate Combfoot
These types of spiders (Steatoda triangulosa) are among the most commonly dark brown spiders in Idaho.
Triangle-shaped bright patterns on the abdomen inspire the name of the species.
Known as a small spider, the Triangulate Combfoot may grow to an adult size of anywhere between 3 and 6mm.
Spiders of the family are further known for relying on spider webs to catch prey.
They lack the good vision of wolf spiders but use web vibrations as guidance toward caught-up insects.
17. Buttonhook Leaf-beetle Jumping Spider
A dark brown to black color is specific to the Buttonhook Leaf-beetle Jumping Spider (Sassacus vitis).
This species has small color differences between sexes as males are darker.
White margins or bands are seen on the thorax and the abdomen of the species.
Various types of flies are part of the common diet of the species.
18. Johnson’s Jumping Spider
Recognizable by their metallic green mouthparts, these spiders (Phidippus johnsoni) are native to the state.
Maximum size of up to 18mm is specific to Johnson’s Jumping Spiders.
They are seen during the day as they rely on very good vision to catch small bugs and insects.
These spiders may wander inside the house but they spend the most time in dense vegetation outdoors.
A beneficial role may be attributed to a small extent to the species which may eat garden and crop pests such as many stink bugs.
19. Cross Orbweaver
Cross Orbweaver spiders (Araneus diadematus) are some of the largest types of spiders introduced to Idaho.
Females of the species are a few times larger than males as they can grow up to a size of over 20mm.
Seen in the central part of spider webs, the female Cross Orbweaver is a spider that bites on occasion, without major medical implications.
These spiders can be brown, or dark brown, or come in an orange-brown morph.
20. Rustic Wolf Spider
Rustic Wolf spiders (Trochosa ruricola) have black bodies and brown or brown-green legs.
They are seen across gardens and woodlands, with a preference for litter to use as a hiding spot.
Female Rustic Wolf Spiders are easier to spot as they move slower since they need to carry an egg sac.
The female Rustic Wolf Spider grows to a size of up to 25mm.