Once they get into the GFX, they hold road grit and it builds up, then you end up with a mass that doesn't want to dry out.
Not to mention the trunk carpeting. A vacuum won't budge them once they lock in that material. Tweezers and a hand reverse-wrapped in painter's tape at that point.
Bad as all that is, the real p i t a is if they're allowed to get into the moonroof drains...which is another reason to clear the GFX in front of the rear wheels.
Good news is since I moved to Salem there aren't nearly so many pine trees where I live now - but I'm still finding them in the SC from living in Portland, and that's been two years. Suckers have a shelf life longer than MREs.