EN
The pupa and imago of Chironomus acerbiphilus (a senior synonym of C. crassimanus) show wide variation of external morphology characters. This paper describes the external morphology of larva, pupa and adult of C. acerbiphilus from Poland. Variability of morphological characters is evaluated for the Polish population in comparison with other European, Asian and North American populations. Pupal suhgeneric characters are discussed.