Its used as an alternative to the expression ' to close the stable door after the horse has bolted. ' for example it is relevant to leaving a situation that is liable to impending doom. Imagine a giant huntsman bursting open with thousands of spiders running around your house. Also relevant to teachers leaving their profession before having a nervous breakdown.
My mate stole from her employer and thought she got away with it but staff stopped speaking to her all of a sudden, so I said to her, don't you think its time to get out before the spiders hatch.
by LIZARDCHOPS January 26, 2018