I know 'tis the season ...

for virgin births and all, but this is puzzling!

My A. laeta had an egg sac. I noticed it several days ago. I got her about 6 months ago. I certainly haven't had her with a male! And then this sac. I thought she was preparing to molt ... she hasn't eaten for several months. But no molt, and an egg sac instead. Today, she appeared to be munching on it. So I removed it, and ... so now what? When will she want to eat again? Why did she do this, not being anywhere near a male? Should I be worried that she is weakened by it all?

T's can hold sperm for a long time-like up to a year before they make a sac.
Also T's will sometimes eat their sac for several reasons. If they are too disturbed, or if they know th sac is no good they eat it to regain some of the nutrition they lost while making the sac.

not only that, they can make an eggsac that is infertile, if they've never been mated. So, two possibilities...either she was mated before you received her, and made an eggsac, or more probable, she made an infertile eggsac then ate it.
I had an A urticans that had never been mated, but every year till she died, she faithfully made a sac, then ate it a couple weeks later!