A couple of inches of any juice in a glass works well too. Don't get any on the sides while pouring it in, this way they have to get "into it" and not off of the sides of the glass. Don't let many accumulate at a time in the glass, they will crawl on each other to get out LOL
I just did this at DB's house, a bag of potatoes was forgotten about there. I put a couple of glasses in each room and within 2 days they were all gone.
