Fruit flies

[Hotzcatz]

The bottles we got at the Waimea experimental station had a wire sized hole drilled in the bottom (betcha with a hot wire you could just push it through the plastic if you didn't have that small of a drillbit) and then a loop in the wire held it inside the bottle. The other end of the wire was bent into a hanger. That left the opening at the bottom of the hanging trap so rain wouldn't get inside. If you had a place to hang it out of the rain then it wouldn't matter which way it was hung up.