Hi all, was wondering if I could get some help here. Ive got a mature arid bioactive with a Uro, the setup is doing great, its almost 2 years old now. It has a diverse number or organisms established now - 2 species of isopods, springtails, detrivorous mites of several species, live cacti, the Uromastyx, and apparently now the subject of my concern…
Very tiny soil spiders. I only found them as I was looking to harvest some springtails, so I was looking very closely. There are not a ton, especially compared to the isopods, but there are several. I’ve tried to kill them as I see them, but they are very small 1 to 3 mm max. They can be white or yellow. At first I thought they were very long legged, large mites, but they have two body segments. I’ve tried to get the best photos I can.
The only thing I can come up with is yellow sac spider spiderlings, but here’s the thing - I’ve NEVER seen an adult spider in there, or webs of any kind. AND, the only thing I’ve introduced in the last year in there that wasn’t sterilized is some hibiscus flowers/leaves from the yard for the uro to eat. Also, in the last month and a half, I’ve only introduced a single sprig of hibiscus leaves as the uro was brumating.
So either:
Somehow spiderlings got in
I accidentally introduced spiderlings on the hibiscus leaves
These are tiny adult spiders that are longstanding members of the ecosystem that I never noticed until now.
Any ideas what these could be? Should I be concerned about them potentially being harmful or infesting the house? Do you think I need to take measures to eliminate them, or is it possible this will be self limiting? Thanks so much for any input.
I see why you think they could be yellow sac spiders given the colour, but the shape of the abdomen doesn’t look quite right for yellow sac spiders, at least to me. It’s going to be really tricky to ID them without knowing what life stage they are, because some species of spider look drastically different as slings vs. juvies vs. adults. Where (generally) do you live? That could help rule certain species in or out (though technically a non-local species could have hitchhiked in substrate or decor).
To give you some peace of mind, I think it’s highly unlikely they pose a risk to your uro at their current size. I doubt they’re a risk to anything but the springtails right now. It’s also highly unlikely they’ll infest your house unless you have a really bad bug problem in your home. Spiders tend to only stick around and set up shop when there’s a good food source for them.
My only concern would be that depending on what species they are, they could potentially pose some risk to the uro as adults (assuming they are indeed slings right now). If you’re in the US, I’d mainly be concerned about true widows (black or brown), false widows, and brown recluses. These don’t look like true or false widow slings at all to me. I’m less familiar with brown recluses because we don’t have them where I live, so I can’t feel totally confident ruling those out, but I feel like the legs on your spiders are too short and stubby to be a recluse.
I’ll add the caveat that I am by no means an expert, I’m just a weirdo who likes spiders, so take what I say with a grain of salt. These are just my thoughts based on the information and pictures presented.
Thanks so much for your reply! I live in SW Florida, so there can be a lot of weird stuff down here. I guess Ill just have to keep an eye on them and make sure nothing bigger arises in the terrarium.
I will say that yellow sac spiders do fit with the lack of webbing you noted. Sac spiders have that name because aside from making egg sacs, the only real webbing they spin is a little silken “sleeping bag,” or sac, they sleep in during the day. But at least as adults, they’re not really what I’d call “soil spiders.” So unless they’re more fossorial as slings than I realize, that behaviour doesn’t really fit the species.
