Post-molt or pre-molt?

[Vulash]

As I've mentioned in a newer owner. I have yet to see a molt in person, although I've read up on the process.

My Acanthoscurria geniculata, a small sling (maybe 1/2" to 3/4") has created a decent burrow under their cork. Often I can't see them, or I'll see partial booty only. It doesn't come out and attack food but the food has always disappeared quickly if I leave it. Even a few days ago.

I hadn't seen it much the past couple of days. Mostly just half-butt. This time on feeding day I left half a dead meal worm in case it was molting out of sight, and this morning it was still there.

I could see half-butt down in there. It looks plumpish, is glossy, and looks bald other than the patch of harpoon setae.

So I'm trying to determine if it's pre-molt or post-molt. Ultimately, I'll just leave it alone either way, but I want to understand what I should be seeing.

I should say as I took these pictures I was able to get a little better view with the flash, and then they decided to spin around a bit (2nd photo) and give an even better view. It's been a bit since I've seen them full on so I'm iffy on the original size, but it looks bigger now. I'm also fairly sure the dark lines in the abdomen are because its currently translucent. I feel decently confident it's post molt, but I'm following through with the post.

Why does it look bald other than the dark patch? My understanding was that the new setae are formed before molting, are they translucent as well? I wouldn't imagine those need to harden

 

[BoyFromLA]

It will molt soon, very soon.

 

[Vulash]

Great, thank you! This means I was wrong, but I can learn from that. I won't bother it anymore with pictures or food.

 

[coolnweird]

Usually, the most notable difference pre and post molt is abdomen size! If your sling had already molted it would be much skinnier.

As for why the abdomen is bare besides the dark patch of urticating hairs, slings often only have a small circle instead of a full abdomen of setae. I'm not really sure why, but the patch expands molt by molt until it covers the whole abdomen. You can see the new set of hairs developing underneath once the current patch of hair has been kicked away!

 

[NMTs]

The criss-cross pattern you can see on it's abdomen is it's circulatory system, showing through because the exoskeleton is stretched thin by the fluid underneath. This happens as it prepares to molt. You'll know a molt is imminent when you can't see that anymore and the abdomen is shiny and almost entirely black, which should be pretty soon - it happens quick when they're slings.