transcriptome analysis of venom glands - (Jan/02/2014 )

I will like to know why spider venom needs to be extracted a few days before venom gland extraction for transcriptome analysis

Extracted from the live spider or from the dead (removed) glands?

I suspect that in the case of live spiders, it will be so that there is a baseline for when the glands were last used, so as to provide a standardized reading.