When a photograph isn't enough

I spent the better part of a year trying to use photos to identify Macaria minorata and Macaria transitaria. After becoming totally frustrated, I got out a ruler and began measuring. M. minorata is reported in field guides as having a wingspan of 17 to 21 mm. M. transitaria is 23 to 28 mm. I see two sizes because female moths are generally larger than males. The smaller ones I've measured run a minimum of 10 to 11 mm along the costa (leading edge of the forewing) for a total wingspan of 21 to 23 mm. The few larger ones that I have measured have wingspans of 25 to 28 mm.

Obviously I see a few that are barely or almost small enough to be M. minorata. However, I haven't found any in the 17 to 19 mm range that would be males. Therefore the marginal ones that I see are male M. transitaria.

Sometimes a photograph isn't enough. Incidentally, the moths in the montage are all phenotypes of M. transitaria. Confusing, aren't they?