Telomeres are important structures at the ends of eukaryotic chromosomes providing stability of their structure. These highly repeated short nucleotide motifs are evolutionarily stable in the phylogenetic branches of higher rank. The conserved repetitive DNA sequence, (TTAGG)n, presents at the telomeres of the majority of tested insects being considered as the phylogenetically ancestral telomere motif in Insecta; but in some insect taxa this telomere nucleotide sequence is absent (lost). Until recently, one of these taxa was suggested to be the true bugs’ order Heteroptera. However, in the last few years we have showed that the (TTAGG)n motif occurs in the family Belostomatidae from the basal infraorder Nepomorpha (aquatic bugs) and in the sister to Heteroptera taxon Coleorrhyncha. Here, we report results of the FISH mapping of telomere (TTAGG)n sequence and, additionally, of ribosomal DNA (rDNA) in representatives of several aquatic bugs’ families.