Size discrepancies

November brings with it for me the ritual of photographing at least one #6745 Giant Gray Moth Cymatophora approximaria and subsequently my surprise about the size listing of 35mm wingspan on its BG species page. “Giant” Gray Moth? The few individuals I have encountered were much larger. In the absence of measurable background features, I determine the size of moths by holding a small plastic ruler close to, and along, the part of the moth I want to measure (most moths, but not all, tolerate this if done gently). Such measurements certainly are approximate, but the percent error is small, especially with large moths. As to the Giant Gray Moth, for an individual I encountered a few days ago I recorded a wingspan of 50mm, and the wingspans of previously photographed Giant Grays were 50, 45 and 48mm. Measurements available from BG-posted images range from 40mm to 51mm (avg. 45.8), excluding one outlier with not fully extended wings and a listed wingspan of 27mm.
The wingspan of Jim Vargo’s pinned Cymatophora approximaria shown on MPG is listed as 34mm. This is a low value even if one takes into account that the forewings of the pinned moth are not positioned horizontally as they are of live individuals. Do wings shrink significantly when they dry? This question had occurred to me recently also in the case of #4956 Ostrinia penitalis for which the BG-listed wingspan is based on that of a pinned specimen and clearly at the very low end as discussed here.
All of this may be much ado about very little, but the above listed discrepancies should perhaps be taken into consideration when the species pages are updated.