cricket, grasshopper
蟀 centers on a specific insect: a cricket or grasshopper. The meanings are closely related, both referring to jumping orthopteran insects.
蟀 combines 虫 (insect) with 率, which likely contributes the sound. The character was created to represent crickets or grasshoppers, with 率 providing the phonetic element.
The insect radical 虫 on the left tells you it's a bug, and the right side 率 looks like a complex net or cage. Picture a cricket trapped in a net, chirping loudly.
For シュツ, imagine a cricket making a sharp 'shut' sound as it jumps: shut -> シュツ, and the cricket shuts its wings after landing.
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