Bat and Moth -> Cub/Scout Game

Update: Apparently this is a game called Marco Polo that I've just never heard before.

Bats eat moths. Bats use a form of sonar to detect moths as they are blind.

Cubs sit in a large circle. One cub is blindfolded and stands in the circle. Ze is the bat. Two or three other cubs are then selected to be the moths. They stand in the circle too. The bat needs to try and tag them.

The bat says "Bat" then the moths need to reply with "Moth". Once the moths say "Moth" they can move up to three steps wherever they like within the circle. The bat can move as much as they like. This continues until both moths have been caught.

So basically, the bat needs to detect the moths using sound only (when ze says "bat" and they reply "moth") so all other cubs must be silent.