虫 (the insect radical) sits inside the upper-right wrap and supplies the literal meaning - 虱 is a small insect, specifically a louse. 虫 groups it with 蚊 (mosquito), 蜂 (bee), 蛇 (snake) and the rest of the creepy-crawly family.
semantic
虱shī
louse with insect-radical core (graphic residue)
The top-right corner is a fused two-stroke remnant - historically a stylised pair of louse legs or claws hooked above the body. Standalone parts here have collapsed into an unanalysable shape, so the residue rides as a single graphic unit framing the bug below.
