Scarab wrote:

For the life of me I can't agree with the stress argument when it comes to egg case production, although I agree it might trigger a moult.

Well, I've seen female roaches release the nypmhs they were carrying while they were caught in the fangs of a T'. So I wouldn't fully exlcude this aspect, but who knows.

Humidity might play a very likely role, but if someone was waiting for their T' to drop a sac, I'm sure that her keeper will have adjusted humidity to the necessary level even before rehousing the spider. It will be difficult to prove as nobody will be able to tell if the T' wouldn't have dropped in any case, in her previous cage, just at the same time?

Leaves room for investigation, and building theories.

I for one don't agree with the stress egg case argument either.

TH

Marula:

So I wouldn't fully exlcude this aspect, but who knows.

You mentioned roaches, but I have heard/seen/read that some animals actually drop their babies prematurely due to stress. This is a survival tactic and aftercare goes out the window. If a Tarantula drops an egg case due to stress, I don't see it caring for it as she would under "normal" circumstances...

Stress in mammals can have devastating consequences for the unborn fetus. I know we are on the spider topic, but reproduction in stressful environs makes no sense. I for one can't concentrate on such tasks when the neighbor bangs on my bedroom window... :blush:

Look, I am not writing it off as a cause for egg case production after rehousing, it just does not gel with what I believe to be "normal" reproduction.

Valid point again, Scarab Some animals seem to actually breed better under stress than normally, but generally speaking I sould agree.

But still, the problem remains: It will be difficult to prove as nobody will be able to tell if the T' wouldn't have dropped in any case, in her previous cage, just at the same time?

So to summarize.

Possible temperature and humidity changes may trigger a moult.
The level of stress a re location causes may trigger a moult.
No conclusive reason exists (yet) why a re location would trigger egg case production.

Let's move on to the next topic then.

What is the difference between male webbing (spider silk) and that of females, if any?

Scarab wrote:

So to summarize.

Possible temperature and humidity changes may trigger a moult.
The level of stress a re location causes may trigger a moult.
No conclusive reason exists (yet) why a re location would trigger egg case production.

Staying on the original topic for a moment if i may. When you rehouse your spiders do you put the spiders into a completely new and clean tank or do you put the old hide or a load of webbing from the old tank into the new one? The reason i ask is that i do this and find that my adult spiders rarely if ever moult soon after being rehoused. I don't mention slings or juveniles as these moult fairly frequently anyway and will only add to the confusion. Much better to limit this topic to adult spiders that we know usually only moult once every year or two.
This talk of stress is interesting as given that tarantulas do not even possess enough neurons to feel pain then how likely is it that they will feel stress which really is just an emotional thing? Yes they will react to negative stimuli but even an amoeba will do that.
Egg sacs being produced after relocating captive mated spiders is not really a common ocurrance but given that a lot of species seem to drop sacs after a warm wet period and a newly set up enclosure tends to be warm with fresh moist substrate then this is probably where the answer lies.