I live on a ranch in central Texas and have quite a few snakes as well as wasps, scorpions, etc. in my 100-year-old pole barn that I use for a garage. So, For the wasps - both mud daubers and paper wasps - I spray them early in the morning before they get active. For spiders - I have quite a few of the big yellow/black garden spiders (genus Argiope) but I leave them alone. I do keep the barn swept and raked and periodically use a broom to knock down spider webs that I can reach, as well as mud dauber nests.

Now, for snakes - I have LOTS of snakes - Texas rat snakes, water snakes, garter snakes, blind prairie snakes, and rattlesnakes. The main ones I have are rat snakes because they eat field mice from the pasture, and so I'm learning to coexist with them. You have to take care of the food source - get rid of the mice - and the snakes will go away. Do you keep any sort of pet food, other animal feed, or anything remotely edible that would attract mice? I keep my dog food in a galvanized metal trash can with a metal lid.

I did try "snake away" last summer after the 10th snake in my house - turns out it is just mothballs, and no, it didn't work. YMMV.

How are the seals along the bottom of your garage door? Have you inspected for holes where critters can get in, and caulked everything?

I would not worry about the snakes as long as they're not poisonous types, because they're eating the mice! Closing up all openings should help with both, unless you're talking about an open pole barn.

People do seem to think the snake repellent products don't work. I wonder if double sided sticky tape or something else simple would help. Try Googling 'how to deter snakes' for some ideas.

It's good to learn your local snakes so you know whether they're a threat to you. Your state dept. of conservation or natural resources should have some fact sheets.

we have a lot of rattlesnakes around, thats why i worry..

Pyrethrum insecticides have a decent longer term effect on surfaces and are not especially dangerous.

Ah, yes, well, with rattlers I understand your concern.

Long ago I was advised to sprinkle agricultural sulfur around the perimeter(interior and exterior) of our concrete floored barn to keep out snakes. I also began using mouse/rat bait traps from the farm store. All feeds are in barrels-so not much to attract critters. Have not seen snakes since, though there are many in the gardens and fields.

Are you able to close up the garage? (Do you have garage doors?) We put up some flaps that go along the side of the garage door where there was a gap between the frame and garage doors. That ended the pesky visitors to our garage. Also keeps our garage water tight now. (Rain used to blow in along those gaps)

We also have snakes in N. Ms. and years ago I quit storing bird seed out there. First the mice came in, then the snakes joined the party to get the mice. Eliminate the food source and close up those holes and bye-bye critters.

Once we closed it up, put out mouse traps and that's a happy ending.

oh boy, i was afraid it was coming. went out to the garage today to get the mower out and when i rolled the mower back, there was a snake! Trying to figure out what kind it is. It was a shiny dark brown with a yellow stripe along its side from head to tail. The front tire of the mower ran over him and he very calmly and slowly slithered under a pile of stuff i have in the corner of the garage. Dont know how to get him out of there..

Wow, and I thought having squirrels and rodents was bad. You guys win. Yuck.

We ended up actually rebuilding our garage because the old one was in such bad shape. Rats were coming up through cracks in the foundation and squirrels and mice were coming in through holes in the siding. We just decided to demo the old structure and build a new one up to code.

Here is a link that might be useful: Garage Rebuild Project