All Aristolochia species make use of complex pitfall traps with a fyke-like mechanism, stiff trichomes ('hair') leading the insect easily inside the flower but preventing them from escape . Although quite a number of species display striking similarities to genera of carnivorous plants, the genus Aristolochia itself is not carnivorous at all.
In fact, these plants lure and trap insects for their survival, namely to pollinate their flowers for reproduction. Many species have adapted to very specialized pollinators.
In a few cases, this coevolution has evolved to such tight relationships for some species that if the respective insect is missing or goes extinct the affected Aristolochia species will follow as well.
In any case the insects are not harmed at all, they will be captivated in the flower for some days and released due to a complex mechanism as soon as the anthers open or the flower is pollinated (stiff trichomes weaken in that process).