Whereas the double-top wing is almost symmetrical and narrow, being bounded by two
s-bends mirroring one another, the less common and less symmetrical double-bottom
wing is very wide and gourd-shaped. Unlike the double-top wing, which has two short
claws like the shorter of the normal claws and one strong double-width central claw,
the double-bottom wing is equipped with two of the longer type of normal claw. Usually
this ungainly wing is caught up untidily in the keel petal: if that doesn't happen,
it flops over the other wing. Either way, pollinator's access is blocked.