This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
蛃 combines 虫 (insect) with 丙, which likely contributes a sound component. The exact historical development is uncertain.
The insect radical 虫 beside 丙 suggests some kind of insect, but the specific meaning is unknown.
For ヘイ, imagine a rare insect making a soft 'hey' sound as it crawls: hey -> ヘイ.
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