underwing(n = noun.animal) - moth having dull forewings and brightly colored hind wings;
is a kind of noctuid, noctuid moth, owlet moth
is a member of catacala, genus catacala
has particulars: catocala nupta, red underwing

1.  One of the posterior wings of an insect. [1913 Webster]

2.  Any one of numerous species of noctuid moths belonging to Catocala and allied genera, in which the hind wings are banded with red and black or other conspicuous colors. Many of the species are called red underwing. [1913 Webster]

underwing, n. a wing placed under or partly covered by another.

red underwing