Reptile & Amphibian Forums

Lately I have noticed my B. smithi has a bald spot on her rear end which wasn't there couple weeks ago.

About a month ago I moved her from a small container to a large 20 gal tank and he seemed to adopt to it well. Explored the entire tank from top to bottom (didn't think Tarantulas could climb glass but she had no problem and spent a couple days hanging off the screen). For substrate I used a mix of untreated potting soil, invert mix and peat moss and have it about 6"-8" deep. I have some fake plants for decoration and a small bowl of water (about 2-3" diameter).

She has eaten crickets fine, so definitely doesn't seem stressed as far as I can tell. However I am not as well versed with T's as I am with other animals so this bald spot is something I don't know about. In birds and some mammals, bald spots could mean stress, as stressed animals often over groom themselves...but I don't know if stress does the same with T's.

Oh and one other thing that's different in this setup than in the old one, is I have a low watt bulb to help keep the cage warm. There is only a 60 watt bulb and the hot end surface temp (of the ground) is about 85F I think it was (I measured awhile ago, before I put my T in, to make sure it didn't get too hot).

I think I covered all the details, so if anybody can give some insight why my T's developing a bald spot, will greatly appreciate it. Oh and one last thing, I don't handle the spider so I know its not stress from handling.

Bald spots appear for two reasons. The first, as you mentioned is stress. They will rub urticating setae off the back of their abdomen if they are irritated. This can be from lots of different reasons. The new environment could be a cause. If it is not completely comfy in its new environment it may be stressed.

Since you have no other indicated reasons, other than the new environment, the other likely reason is an upcoming molt. When they are coming up on a molt, they will usually develop a bald spot. This can be a month or two out. When the molt gets about a week away, the bald spot will turn dark. A bald spot alone does not always mean a molt, but if it turns dark, it is certainly a molt.
-----
KJ Vezino
My Gallery
Missouri Tarantula Enthusiasts Group

I don't know if he's stressed...as I never see him flick hairs...well he did flick hairs at me when I took the water dish out but I think it was only because he was right beside it. HE didn't flick them when I put the water dish back in the same spot. (I use a small ceramic dish, about 2" diameter since he's grown much larger than 2" in body length. I figure there is no chance of him drowning.

Its been about three months since the last molt...I think...and I have been feeding him a bit more often in the new enclosure and he eats (often jumping on the crickets as soon as it hits the ground). I will keep my eye on the bald spot and see if it gets darker...right now it looks a light tan..kind of leather like in color.

For reference:

Here is a fresh bald spot:

Here is the same spot when it darkened, 1 week prior to molt:

-----
KJ Vezino
My Gallery
Missouri Tarantula Enthusiasts Group

thanks for the pics Vez The top picture is exactly what the bald spot looks like on my B. smithi...it hasn't gone dark like the second picture yet. Hopefully when mine does molt, it is intact so I can get a good picture of it and see if I can get my spider sexed (or at least I heard some people can sex T's by their molts).

Molts are the most reliable method for sexing. At 3" or bigger it is easy with the naked eye. 2-3" is easy, species depending. down to 1" can be done with some digital manipulation with a high res camera. SMaller than that can be done with a microscope.

When it molts, if you can post a pic, I can help you out.
-----
KJ Vezino
My Gallery
Missouri Tarantula Enthusiasts Group