According to Asan, you chew up a piece of gum really well, and tie it on the end of a string. Then you drop the gum into a tarrantula hole in the ground (looks like a fire ant hole, apparently, but bigger). The little critter bites down into the gum and gets stuck, at which point you can pull him out. Then you and your five-year-old male Tico friends can set them up to fight each other.
Oh...and many thanks to Doug and Debra for initiating us into the world of tarrantulas and scorpions, because Khalida sure didn't warn me to turn on a light and look around before I reached my hand into the laundry bag!!