tiny snail chewing my Oncidium PBs

[stefpix]

My Onc Twinkle had some holes on the pseudobulbs.
tonight I finally caught [and squished] a tiny 2 mm diameter snail that was chewing on it.

what is the remedy?
I had just repotted it after blooming in coco chips and has some new growth.

many old PB have now some small scars.

I have a pyrethrin based spray and a spray bottle with a mix of alcohol, water and a few drops of dish soap.

what are those small 2/ 3 mm snails?
how can I make sure i eliminate them all? do they reproduce a lot?
thanks