This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
蛁 combines 虫 (insect) with 召, which likely provides the sound. The exact historical development is uncertain.
Since the meaning is uncertain, picture an insect 虫 that responds to a call 召, like a cicada that chirps when summoned.
For チョウ, imagine a distinctive insect named Chou: Chou -> チョウ, and the insect 虫 is called 召.
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