Originally Posted by gypsmjim
The walls are too thin and the wood is not stout enough for a molly. It will crush the wood, reducing the holding power.
Use a toggle bolt.
A toggle bolt will do more damage to a wall than a molly. Hollow wall anchors (aka MollyBolts) use four flat prongs that expand when the screw is tightened, spreading the load out to all directions, whereas a toggle bolt has only two prongs that only hold in two directions and have thin edges that will dig into the wall material.
Toggle bolts require a larger hole than hollow wall fasteners and, if you ever remove the screw, will drop down into the wall.
I have used both and will never use toggle bolts again.