Why should photographs intended for citizen science reporting focus on the hind leg profile?

To clearly show the absence of corbiculae on the tibia

While the general yellowish coloration of the Yellowish Cuckoo Bumblebee is striking, its variability makes it an unreliable identifier on its own. Therefore, for rigorous documentation, such as citizen science reporting or biodiversity studies, capturing a clear photograph of the hind leg profile is crucial. The most definitive evidence supporting an identification as a cuckoo species is the structural confirmation that the bee lacks corbiculae; the tibia should appear smooth, hairy, but unspecialized, lacking the distinctive pollen-carrying apparatus. This anatomical absence provides much stronger, objective evidence for confirming the parasitic identity than relying on subjective interpretation of variable color patterns.