I like to spray them with paint and watch them run around on fire.
When I was younger we had horses. With horses come flies, and lots of spiders. I used to shoot them point blank with my pellet gun pumped up to 10. Even without a pellet, just the air blast vaporizes them. When I got older, we were remodeling a house. I had just hung all the sheetrock and a huge wolf spider ran across the wall. I got the pellet gun out, pumped it to ten, and let him have it.......nothing. It just fluffed up the hair on his back. After that I loaded it up and had some target practice. After missing him a dozen times, It took 2 direct shots to put him down. Big bastard.