Shows a mosquito—bites, itching, pests, summer, or disease caution.

Shows a bug—an insect, or metaphorically a software bug, glitch, or issue.

Shows a cockroach—pest, dirty places, toughness, ‘survives anything,’ or gross‑out humor.

Shows a beetle—bugs, hard shell, nature, or entomology topics.

Shows a worm—soil, compost, bait for fishing, or a gross‑out joke.