Chris,
The "theory" is that the foil reflects light up to the underside of the leaves thus confusing the bugs.....
If you get the light color Centex totes at Lowes, There is no need to wrap the sidewalls in foil, as they have a lifetime guarantee. I had not had a single one deteriorate due to uV. Also, the reflections of the Sun off of the foil would drive me (or your neighbors) nuts.
Raybo
