Testis follicles of ninety-four mirid species are listed: subfamilies Phylinae, Dicyphinae, Orthotylinae and Mirinae have modalities of 3, 1, 2 and 7 respectively. Other features—pronotal collar, pretarsus, venation, genitalia, eggs and diploid numbers—are reviewed in the light of new information and a fresh grouping of subfamilies is suggested: Isometopinae; Bryocorinae; Mirinae + Deraeocorinae +?Cylapinae; Dicyphinae + Orthotylinae + Phylinae. The current tribal divisions in Orthotylinae are untenable and the distinction of this group from Phylinae is blurred. Membranous arolia have arisen twice in Miridae, the family originating from a nabid-like predatory ancestor. The two-celled membrane is more primitive than the one-celled, but retention of ocelli by Isometopinae is also a primitive feature. Species aberrent in follicle number include Alloeotomus gothicus and Oncotylus viridiflavus (indefinite follicle number); Stenotus binotatus and Leptopterna spp (additional follicles); Notostira elongata, Orthocephalus coriaceus and Cyrtorhinus caricis (departure from subfamily norm): Deraeocoris is polyphyletic. Analysis of feeding habits has disclosed marked intersubfamilial differences.