Help ID this aggressive spider

[Keen observer]

This was filmed with my phone.

[video=youtube;Jz-_VEDYHUw]http://www.youtube.com/watch?v=Jz-_VEDYHUw[/video]

I live in WA state.

My mind screams Hobo Spider but I've never encountered one of those and pictured them to be bigger. Is this just a typical house spider messing with me?

 

[Ciphor]

Hello,

First, you should read this about hobos http://www.burkemuseum.org/spidermyth/myths/hobo.html (the owner of this page, Rod Crawford is a professional arachnologist in the pacific northwest)

Most experts agree, they are no longer considered dangerous thanks to research and testing.

That being said, the spider appears to be aggressively chasing you, however, this is random coincidence. It's hard to ID a spider that is blurry like that, but knowing your geographic location, the fact you are indoors, and having a general idea of how the spider moves and looks; I'd bet the spider is a male Steatoda grossa (false-black widow). http://bugguide.net/node/view/664244/bgimage

They are not dangerous, and quite beneficial in your home as they eat many other spiders and pests while staying out of sight. The one exception is when males go wandering in search of a female which is what this spider is likely up to in your home.

Last thing, and the reason we can conclude the spider is definitely not chasing you. These spiders, and most spiders have very poor eye sight. On a good day, this spider sees changes in light however cannot make out distinct objects like a person standing in front of them. It is very possible the spider saw you and your shadow as a dark spot while bathed in the rooms light, and he was running to get into the shadows where he is safer and more likely to encounter a female.

 

[Keen observer]

Hello,

First, you should read this about hobos http://www.burkemuseum.org/spidermyth/myths/hobo.html (the owner of this page, Rod Crawford is a professional arachnologist in the pacific northwest)

Most experts agree, they are no longer considered dangerous thanks to research and testing.

That being said, the spider appears to be aggressively chasing you, however, this is random coincidence. It's hard to ID a spider that is blurry like that, but knowing your geographic location, the fact you are indoors, and having a general idea of how the spider moves and looks; I'd bet the spider is a male Steatoda grossa (false-black widow). http://bugguide.net/node/view/664244/bgimage

They are not dangerous, and quite beneficial in your home as they eat many other spiders and pests while staying out of sight. The one exception is when males go wandering in search of a female which is what this spider is likely up to in your home.

Last thing, and the reason we can conclude the spider is definitely not chasing you. These spiders, and most spiders have very poor eye sight. On a good day, this spider sees changes in light however cannot make out distinct objects like a person standing in front of them. It is very possible the spider saw you and your shadow as a dark spot while bathed in the rooms light, and he was running to get into the shadows where he is safer and more likely to encounter a female.

Well that was quite enlightening. Thanks for the link!

I am not certain of that classification but it may be a possibility. From what I've read in that article, I need to get a closer look to identify a Hobo spider. I'm guessing this is the case for any spider.

This was recorded sometime around 9 or 10 PM so I'm not sure if it was my shadow (vid was filmed in a well lit hall) but that does sound plausible.

Also, I should mention that it's palps were noticeable. So it was a male spider?

 

[The Snark]

Just a suggestion. When trying to identify a spider, don't go by what it is doing at a certain time. Contain it and get as clear a picture(s) of it's anatomy as possible. Honestly, the only spiders that can be identified with reasonable certainty by movement are salticids. The next thing to note are as you mentioned. enlarged palps which /could/ indicate a male searching for romance. That, of course, identifies only the sex, not what the animal might be. That could be taken one step farther by closely examining it. If it appears to be a web dweller, which with many spiders is reasonably obvious, perambulation is more likely to be romantically motivated. In the case of your video, the uncoordinated gait of the animal probably screamed web dweller to Ciphor and the commonest galumphing house intruder in your neck of the woods is the steatoda.

Of course all the above may be discounted if you have established in the past that you attract spiders naturally. If that is the case, the entire world of arachnophiliacs would very much appreciate you turning yourself in at the local critter lab for analysis.

 

[Ciphor]

The most important identifying factor is not appearance for this spider to be honest.

The fact its a male out in search of a mate is. This time of year in our state very very few males are out wandering that could match that spider.

As a mater of fact, the only male spiders besides a house spider that is possible this late in December I believe is Zygiella x-notata/atrica, which is not wide spread in WA state. If you gave me a city location, I could rule it out for sure.

There are a handful of male Linyphids out and about this time of year also, but most of these species stay in forests, and avoid man-made structures. They are also much smaller then this spider appears, especially in body length.

Given its in your home and a male in search of mate in late December, I'm about 99.99% certain it is Steatoda grossa.

BTW it is definitely not a hobo spider, or any Agelenid for that mater. Males in this family head out for mates around late august/sept. That spider is also waaaay to slow and clumsy for anything in the funnel-web spider family, which contains the land speed record holder for true spiders, Tegenaria gigantea a very close cousin to the hobo (Tegenaria agrestis). We have them here in WA too.

Take my word on this one

 

[John Apple]

Ill second that after trying to look closly....looks like a male grossa to me.....I occasionally find one in my basement...[not native but 'naturalised' in my basement]...as well as adult females when I need one

 

[Keen observer]

@The Snark Yeah I figured as much. Also, I recall having a spider that stuck around on the ceiling right above my pillow... I couldn't sleep for hours!

@John Apple what do you mean by "naturalized"?

The most important identifying factor is not appearance for this spider to be honest.

The fact its a male out in search of a mate is. This time of year in our state very very few males are out wandering that could match that spider.

As a mater of fact, the only male spiders besides a house spider that is possible this late in December I believe is Zygiella x-notata/atrica, which is not wide spread in WA state. If you gave me a city location, I could rule it out for sure.

There are a handful of male Linyphids out and about this time of year also, but most of these species stay in forests, and avoid man-made structures. They are also much smaller then this spider appears, especially in body length.

Given its in your home and a male in search of mate in late December, I'm about 99.99% certain it is Steatoda grossa.

BTW it is definitely not a hobo spider, or any Agelenid for that mater. Males in this family head out for mates around late august/sept. That spider is also waaaay to slow and clumsy for anything in the funnel-web spider family, which contains the land speed record holder for true spiders, Tegenaria gigantea a very close cousin to the hobo (Tegenaria agrestis). We have them here in WA too.

Take my word on this one

Tacoma.

Glad to know it's nothing to worry about! :tongue: I regret trying to "intercept" it (fortunately, it hasn't been harmed in any way. Either I have bad aim or this spider is way lucky...).

Is it true that the ones found indoors are adapted to that environment, not necessarily arriving from outside?

 

[zonbonzovi]

It's coming right for us!

I was going to ask you (Ciphor) what tiny males(10-15mm legspan) might be out and about this time of year but couldn't get any quality shots. These are hanging around the porch light, eyeballing the midge-like flies congregating there. The Zygiella I've seen very ocassionally during the "dark time" in the past few years but those are a bit larger. Oh well, will have to try again if I see any more. Tacoma! Go eat at Dirty Oscar's Annex if you haven't already

 

[John Apple]

Naturalised.....lol......I have them in my basement now...I remove adult females and find wandering males year round......they have cohabbed with the S. triangulosa and pholcus down there

 

[Ciphor]

Naturalised.....lol......I have them in my basement now...I remove adult females and find wandering males year round......they have cohabbed with the S. triangulosa and pholcus down there

I like how S. grossa will always find a spot no mater what spiders are in your home.

I was going to ask you (Ciphor) what tiny males(10-15mm legspan) might be out and about this time of year but couldn't get any quality shots. These are hanging around the porch light, eyeballing the midge-like flies congregating there. The Zygiella I've seen very ocassionally during the "dark time" in the past few years but those are a bit larger. Oh well, will have to try again if I see any more. Tacoma! Go eat at Dirty Oscar's Annex if you haven't already

Do you live by the edge of forestry? Do you remember what general color it was? Light, Dark, Any visible pattern? Banded legs or solid?

If you know for sure it was not an orb weaver, it was pretty likely a sheet web spider (linyphid), and with WA state having an insanely diverse sheet web family, a lot still un-described or in process of being described, Best you could hope for short of sending it in to Rod in a vial, is a genus ID. Chances are these are females enduring the winter, and not males mating, making it tougher to guess (did you see swollen palps?). If I were to make an educated guess based on time of year and the fact they are hanging out by your porch light, I'd say a species of Bathyphantes or Neriene

Is it true that the ones found indoors are adapted to that environment, not necessarily arriving from outside?

Correct. Some spiders, like Steatoda grossa have adapted very well to living along side humans in and around their homes. Males of many spiders however will turn up in your home, especially during the summer.

 

[Keen observer]

Correct. Some spiders, like Steatoda grossa have adapted very well to living along side humans in and around their homes.

Males of many spiders however will turn up in your home, especially during the summer.

Glad to kno- what?! :-o

Interestingly, of all the spiders I have on video (total of 8), only 2 were found in summer time. How well hidden are they?

 

[zonbonzovi]

Do you live by the edge of forestry? Do you remember what general color it was? Light, Dark, Any visible pattern? Banded legs or solid?

If you know for sure it was not an orb weaver, it was pretty likely a sheet web spider (linyphid), and with WA state having an insanely diverse sheet web family, a lot still un-described or in process of being described, Best you could hope for short of sending it in to Rod in a vial, is a genus ID. Chances are these are females enduring the winter, and not males mating, making it tougher to guess (did you see swollen palps?). If I were to make an educated guess based on time of year and the fact they are hanging out by your porch light, I'd say a species of Bathyphantes or Neriene

Carapace solid colored, almost black...legs tan(ish), no striping and definitely swollen palps. I live in a semi-rural area with a lot of 2nd growth timber. Bathyphantes is quite similar...maybe it'll come back for a visit. Thanks, C