Here's how to make one, according to this NatGeo article ... the sloped sides will trap the bed bugs like a moat so they can't get out. According to the study (linked below) they also sprayed ...

1. Choose a location for your trap on flat ground near vegetation. 2. Use a trowel to dig a small hole. 3. Place a clean yoghurt pot in the hole. Fill in any empty space around the pot with soil. Make ...