caterpillar
蠋 centers on a caterpillar, the larval stage of butterflies and moths. The meaning is specific to this insect form.
蠋 combines 虫 (insect) with 蜀, which likely contributes the sound and may have originally depicted a type of caterpillar or silkworm. The exact historical development is uncertain.
The insect radical 虫 on the left hints at a bug, and the right side 蜀 looks like a caterpillar with its segmented body and tiny legs. Picture a caterpillar inching along a branch.
For チョク, imagine a caterpillar munching on a leaf with a distinctive 'chok chok' sound. The sharp 'chok' cues チョク as the caterpillar eats.