Intake air box vacuum line?

[wisehunter1]

So I know this has already been asked but I can't seem to find a definitive answer. There is a small vacuum? hose attached to the stock airbox. I've installed an aftermarket intake but don't know what to do with this hose. Right not, its zip tied with my IAT sensor right up against the new filter. Should I plug it with a screw, let it sit there and do nothing, or reroute it behind the filter? And what does this hose do?