sentences:  The chemical structure of the pheromone utilized by the male "A. aperta" is currently unknown; however, physical contact is not necessary for the induced passive state.Eunuch males, or males with partially or fully removed palps, are unable to induce the passive state on females from a distance, but can induce quiescence upon physical contact with the female; this suggests that the pheromone produced is potentially related to sperm production, since the male inserts sperm from his pedipalps, structures which are removed in eunuchs.This adaptation has most likely evolved in response to the overly aggressive nature of female spiders.