immature locusts
蝻 refers specifically to immature locusts, the nymph stage before they develop wings.
蝻 combines the insect radical 虫 with 南, which likely provides the sound ナン. The character is used for a specific type of insect, the immature locust.
The insect radical 虫 on the left tells you it's a bug, and the right side 南 (south) can remind you of warm southern regions where locusts swarm. Picture a young, wingless locust hopping in a southern field.
For ナン, imagine a young locust nymph munching on a nan bread in a southern field: nan -> ナン, and the insect is still immature.
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