後翅 is read as こうし (koushi) and means hindwing.
こうし
koushi
こうりん
cantle
あとがき
afterword
ごさい
second wife
こうえん
support
こうき
latter period
こうほう
behind
あと
after one's death
こうはん
second half
うしろ
back
こうしゃ
the latter
こうはい
junior (at work, school, etc.)
あとまわし
putting off