The insect radical, used broadly for small flying or crawling creatures. Old classification lumped the bat in here, so 蝙 carries the bug radical despite a bat being a mammal.
Gives the sound: biǎn shifted to biān. It contributes only the reading and ties 蝙 to 编 and 篇, though a bat's flattened wings make the flat sense a handy mnemonic.
