Larvae ofEuscorpius carpathicussettled on conspecific adults can distinguish between males and females on a chemical basis, with females being preferred to males. The preference for different females depends on their reproductive phase, with mothers being the most preferred.E. carpathicusfemales offer a better chance of survival against dehydration when mothers than before parturition, and in both cases a better one than males. This proves that the water passage is an effective specialized mechanism which appears periodically and contributes (to what extent is not known) to improving larval survival, especially in dry periods and/or environments.