If you dip your LR
in pure R/O water, I'm sure that EVERYTHING on the rock will attempt to abandon ship or die trying. I don't think that is a very good way to treat expensive LR
. I think it damages countless life forms that you don't even know about in order to get at one particular life form that you happen to be able to see.
I venture to say that the manis might be one of the toughest species living on that rock.
I have no elegent solution to getting rid of your mantis (I've got one of my own I'm trying to find)....I'm just suggesting that you consider that the treatment may harm your LR
in ways that you can't see.