Any harmless garter repellent?

[Charis]

Weird question for this group, I know! Most want to know how to attract garters, not get them to go away. But I was talking with a friend and her daughter and son in law are having an issue with garters. They have a hollow under their outside stairs that a family of garters have been using as a den the last few years. Didn't bother them too much to start with when it was just two or three of them living there but now there are several generations living there, increasing more every year. They are worried they will soon be over run with them. They also are worried enough about them possibly biting their two year old that they don't let her play outside. Don't think they could be talked into believing that the garters are quite harmless, even to a toddler but admirably, they don't want to hurt the snakes, they just want them gone. They are planning on replacing the stairs and doing away with the den in a year or two anyway, whenever they have the money. But they want to know if there is any kind of smell or something that they can put down to drive them off, that won't be harmful to anything. I told my friend that I would ask around. Is there any such thing?

[guidofatherof5]

It's a shame it's come to evicting them.

[Selkielass]

Landscaping with lava rock is supposed to deter snakes. I have also heard that snakes avoid areas sprayed with strong smelling herbs and oils. (Garlic and cayenne pepper I have heard. PineSol might work too.)
Eliminate all nearby water sources. (Fountains ponds damp ditches.)

Too bad they 'need' to be discouraged.

[katach]

Have they thought about moving and selling the house dirty cheap to me?

[ssssnakeluvr]

there are no snake repellants that I know of... replacing the stairs and blocking the holes during the summer while the snakes are gone for the summer is the only way to keep them out

[thamneil]

That's unfortunate that they must evict the snakes. I would love to have a snake den under my house. As for deterrents, I am unsure that anything would work without harming the snakes. The best option would be to build a snake proof barrier. They could use expandable foam to seal any holes up.