The number of testicular follicles and ovarioles provides valuable data for taxonomy and phylogeny of insects. Among true bugs, the number of follicles per testis varies from one to eight, with seven follicles being modal and probably
the ancestral state in Heteroptera in general (found in over 36% of studied species). The number of ovarioles per ovary varies from two to 24 and the number seven clearly prevails being found in 48% of studied species. Although
data are available for all infraorders except Enicocephalomorpha, more than 60% of studied species belong to the Cimicomorpha. The number of follicles (and, to a lesser extent, ovarioles) has been extensively used as a potentially
important character for the higher-level taxonomy and phylogeny of the family Miridae. In total, data on ca. 300 species (less than 3%) are currently available. Eight subfamilies and 39 tribes are generally recognized within the
Miridae, and data for many of these taxa are clearly insufficient due to sampling bias. Available data for better-studied taxa shows a stable pattern of follicle numbers at the tribal and sometimes subfamily levels. In Dicyphini, a sister clade
to the remining Bryocorinae, the presence of a single follicle per testis was documented for all 27 examined species from four genera. The same appears to be true for the monotypical tribe Felisacini (two species examined). The modal
number of one was observed in the small tribe Bryocorini. Seven examined species of Monaloniini have either one or three follicles per testis, while the largest tribe Eccritotarsini remains almost unexamined. Forty-three examined
species of the largest tribe Orthotylini (Orthotylinae) have two follicles per testis. In the tribe Halticini (Orthotylinae), the follicle number ranges from one to three. Almost all species (>50) of the large and diverse tribe Phylini (Phylinae)
have a remarkably stable follicle number of three. The modal number for the tribe Pilophorini is also three but only four species from the genus Pilophorus were studied to date. In the tribe Deraeocorini (Deraeocorinae), the follicle number ranges from one to eight and no apparent pattern could be established at this point. Among the Mirinae, the largest and the best-studied plant bug tribe (>70 species examined), Mirini unequivocally show seven follicles. Stenodemini, the second well-examined tribe (>30 species), which forms a sister clade to all other tribes of the family, also have the modal number of seven. However, stenodemines demonstrate an exceptionally high diversity of follicle numbers ranging from one to eight. Various authors documented contrastingly different numbers for different species of the genus Stenodema (from three to seven). These and some other patterns will be discussed during the talk.