Lucked out a few weeks back & the LGS had .38 snake shot on hand. Bought 3 boxes of 10 - at $15 per box! Patterned at a few distances out of the 4" .357 - I can at stay at most 7 yards away and have a good enough pattern.
And it works. So far, only have one with the .357. Did get 3 others with the single shot 16 gauge - but it was a bit cumbersome to carry on the riding mower.
I was talking with my chiropractor about the problem. He told a story about how his grand-folks had an old well with a bunch of garden netting thrown down next to it - they'd find dead snakes in it all the time. Took some of that netting and tossed it behind the shed, took a few days but there's one to it's credit too.
Broke down and bought one of the commercial snake traps; it's a corrugated plastic box with glue traps and felt dots that spent some time in a cage with a bunch of mice. It's on one of the top shelves inside, along with a bunch of other glue traps I made using multiple rat-sized glue traps and cardboard - so far one of the home-made traps has produced one snake kill. Others have caught multiple lizards, crickets & a couple mice.
Between the multiple glue traps and numerous bug bombings, I'm hoping to soon be the only living thing in there.
