As we know EM waves have a wave length. Well, how do you measure them? I have the feeling there is a path from point A to point B and that path goes up and down at a regular rate and all photons travel along that wave-path and that they are no where else between A and B but on that path. But that view I have a feeling is incorrect. I think it's more probable that the photon occupies a probability space and that the line a photon is almost never here is a bit arbitrary and that is the length of the EM wave.
Also, I want to double check. I looked at wiki and I saw that the size of a photon is not listed prominently. Is that because they are bosons and can occupy the same space? If they can occupy the same space, then you can't measure their size.