moth, insects which eat into clot
蠹 centers on destructive insects that bore into and consume materials like cloth or wood: a moth or similar pest that eats away at things.
蠹 is a phono-semantic compound: 䖵 (insects) provides the meaning, while the upper part likely contributed the sound. The character specifically refers to wood-boring or cloth-eating insects.
The bottom shows two insects (䖵) working together, while the top suggests a stone (石) under a cover (冖). Imagine moths hidden under a stone, eating away at cloth.
For ト, picture a tiny moth landing on your toe: toe -> ト, and the moth starts nibbling at your sock.
Yakudza vicarius (species of moth)