Cytological parameters are nowadays being increasingly and intelligently used in solving the taxonomic problems of dubious species. Aphids’, in certain cases atleast, taxonomy is not stabilised at the species as well as at the subgeneric level. It is because of the usual occurrence of race or biotype in natural population. Occurrence of such taxonomic categories are possibly due to chromosomal rearrangements or otherwise that resulted from the association with a host plant, as evidenced in a few species, viz,Myzus persicae, Brachycaudus helichrysi, Tuberolachnus salignus etc. Several ecogeophysical factors are operative in establishing chromosomally distinguished races which demand the attention of taxonomists for further taxonomic evaluation of the concerned species. Attempt is therefore made to discuss the rationale of using the cytological informations in the identification of infraspecific categories of aphids.