Gotta do some work in crawlspace. Lotsa critters naturally live there - some creepy, some dirty nasty, some poisonous (Recluses & Widows popular here).
It would be nice if I could bomb the crawlspace like with those ones they have for inside the house where you set and vacate for a few hours. Trouble with those is they spray high and I believe must be vertical to empty.
Of course I would not do anything Darwin like go under house and try and set and back out the 25-30 ft over pipes and ductwork. My thought is fortunately at the far end is a dryer vent hole in the floor. I could reach down from in the house and set a couple off. At the near end (near to crawlspace entrance) I could discharge a couple there.
OK, beat me up here on this not thought through very much scenario.