It happens more often than not, so I was wondering what opinions are floating...

On more occasions than I care to recall, rehousing a spider triggered a moult. It has also happened that rehousing triggers the production of an egg case.

(I read an article on M balfouri kindly sent to me by Hendrijs. It stated that studies in Sokotra have shown that burrows in the wild are often found with only an exuvium, suggesting that the spider relocated after the moult.)

Why?

Interesting topic Scarab

At first I thought it might have something to do with the urticating bristles they sometimes line their moulting mat with... but then again some T's don't do that, and some T's line the entrance of their burrow with it anyway... So why would their own urticating bristles be a problem for them?

Tarantulas generally moult and drop sacs at set times of the year so i imagine the change in set up simulates a change in season which "tricks" the spiders into moulting or producing a sac.
Does the article state the sex of the skins found in the burrow? Could be they are from males that have matured and went wandering.

Do theys say if the exuvariums was from male or female T's.
My bet would be that it is the burrows of males that matured and went on a tour seeking females and never return dus leaving the molt behind.

Other than that i dont have a clue....

I have also experienced the molting after rehousing phenomena.

With fish, you can trigger egg production by adding colder water to a tropical tank.
A new enclosure might trigger a similar response by means of a temperature differential from the old to the new.

Problem with our hypothesis is this, that none of us can prove anything scientifically, we only speculate.

How do we eliminate the variables?

TH