How to find where the slugs are coming from

Every morning in our newly bought house we are finding fresh dried tracks of slugs in our kitchen. I would like to know how to find where they are coming from and how to stop them from entering the house. Has anyone encountered such an issue?

EDIT-1: Made some interesting discoveries last night. The slugs don't enter if the room is lit. When we turn off the lights, they slowly start showing up. So I took my hand torch and came back after about 45 minutes and one was poking its head from a space underneath the drawers which are beneath the kitchen counter top. After I got rid of the first one, 3 more came in when I came back after 2 hours 🙁 I still need to figure out if there are any cracks or holes through which its entering from the outside.

Found this useful link: http://www.allaboutslugs.com/slugs-in-the-house/

EDIT-2: Here's what I did to control them from entering: Removed the wood chips near the wall for about a feet and put paver sand and line of Uncle Ian's slug repellent. In the morning, the slugs braved the sand but I can see the U-turns in the track once they encountered the repellent. I chose that since it had only dried blood and cinnamon. No toxic stuff. But it was very irritating to the nose. As soon as I opened the bag and started applying it, I kept sneezing 4-5 times.

EDIT-3: Adding my comment as an edit here. The Uncle Ian's slug repellent only helped a little. Ended up taking out the board underneath the kitchen sink and the corner shelf beneath the kitchen counter and found out there was a big hole in the floor board. The previous owners moved the kitchen sink from the corner to its current location and both of them had holes which were not properly sealed. The slugs were coming out of those two gaps from the crawl space. So I bought the Styrofoam spray, filled the holes and boarded the shelves back. After that we didn't see the slug in the kitchen – knock on wood 🙂