In their adult form, stealth butterflies possess a single black wing that never flutters, and a long, spiral tongue tipped with a microphone. Rather than indulging in the succulence hidden within flowers, they prefer the auditory nectars of the human voice. They travel from window to window in swarms, pressing their tessellated bellies against any surface that will resonate.
As caterpillars, they form cocoons inside telephone wires, warmed by the electricity of unfamiliar voices. It is here that they learn which patterns of speech provide them with the most nourishment. They thrive on infidelity, wiggle with delight at perversion, and grow plump on profanity. Once fully developed, they can taste a single drop of sin in a jar filled with bass.
It is illegal for lepidopterists to own the corpses of stealth butterflies; their tiny, triangular bodies are filled with secrets much too valuable to be pressed between panes of glass. When one is found, it's best just to leave it be; someone authorized will be along shortly to collect its remains.
Funeral procedures for stealth butterflies are classified, but are said to involve powerful magnets.