Might be better if you could describe the symptoms you're seeing on your pansies, plus info on where they're growing, how long you've had them, etc., and a photo if possible. YOu might be interested in reading the RHS link below - whilst woodlice may take advantage of damage inflicted by another creature, mostly they don't touch plants - but will eat damaged strawberries and may nibble seedlings (despite all the anecdotal stuff on the web about woodlice eating plants)

https://www.rhs.org.uk/advice/profile?PID=723