Came home today and looked to the small table by the apartment door and saw this little cutie.

This is a Tan Jumping Spider, Platycryptus undatus, probably a female since its body length was 13mm.

I scooted her into a jar and spent about 40 minutes taking pictures of her before releasing her into our balcony garden. As with most jumping spiders, she was quite curious about what was going on and was always very interested in visual changes (jumping spiders hunt visually and don’t build webs for themselves, although some will steal food from other spiders’ webs).

I named her Georgette. :)


Found this pretty gal today at my mom’s house!

She’s a little Platycryptus undatus or tan jumping spider. They move in short, quick bursts so they can be startling to find but do not squish! They are harmless to you and not aggressive. This one was quite gentle (and fuzzy, lookit all that fuzz!), and she was amicable to being relocated to the garden bed after a few pictures.

so i have this project going where every time i find a species of spider i can identify, i embroider it. i’ve been doing it since late 2009 and have 17 done and 5 in progress right now because during summer i find them faster than i can get them finished. anyway i’m thinking about putting them on here because i need to have them photographed anyway for when i get a website to further my pipe dream of getting paid to sew pictures for people, and if i can’t blatantly self advertise on my blog, where can i? so open call tumblr, is there anybody else on here who’s into entomology and hand embroidery, in a more artsy than crafty kind of way? want to be best friends? also, any of our followers who are going to shit a brick if they see spiders all up on their dash should speak up now. -r

I’ve been seeing the this type of spider all the time in our house lately. I know there are some venomous types of spiders that are fairly common in households in our area (Missoula, MT) and I don’t think this is one of those, but it has me a little concerned. So what exactly is this guy, and is he venomous, benign, or what?


You’ve been seeing jumping spiders. I think the one in your photo is Platycryptus undatus and I know she’s a female. The females have larger, longer abdomens than males. All jumping spiders are harmless; they’re not dangerously venomous at all.

spiderzrawesome said:

I found a huge male Platycryptus Undatus thats bigger than Peanut. I named him mustache. (The orange coloring under their eyes) he did his dance but Peanut was very scared as if she thought mustache would have her for dinner. Is this normal when a male is larger than a female?

I’m not sure. You’re very good at asking me questions I’ve never considered or researched before! I’m going to have to edit my personal info, downgrade my knowledge base. :)

It seems like she’s still not mature. Spiders of the North Woods (Weber) says females grow to lengths of 10 to 13 mm and males, 9 to 10 mm. Wikipedia says roughly the same thing, stating females are from 10 to 13 mm and males are between 8.5 to 9.5 mm. The Wiki article seems to have gotten its measurements from Kaston, who identifies the spiders by the outdated genus of Metacyrba. Oops- though, to be fair, his book was published decades ago (initially published in 1953; my copy is from 1972).

So everyone seems to be in agreement that the male is smaller than the female. Which means Peanut probably isn’t fully grown yet- she may not even be sexually mature, if her reaction to Mr. Mustache is any indication. Though I’m still leaning towards her getting ready to molt- the process is initially a bit uncomfortable, so she isn’t hungry and wouldn’t want to mate.

I suggest keeping him away from her until she molts or you figure out what is happening with her.

(Made public for anyone else who was curious about size and to show me actually using text sources.)

Not a great photo but they are so tiny they’re really hard to get pictures of. There’s at least five that have emerged so far. Also they don’t behave and have crawled through the holes on the lid to walk around on the underside of the tissue paper I taped on to keep them from escaping >:C If anything brushes the top of the lid they could be hurt ughh dumb babies I’ll have to figure out how to prevent them from doing that