An annotated list of 130 scale insect characteristics, which cover morphology, development, genetics, ecology, etc., is provided. The list contains features (character states) considered to be coccid autapomorphies, presumed coccid sister—perhaps aphid—group synapomorphies, and selected hemipteran plesiomorphies; apomorphies of all lower taxa (superfamilies, families, etc), were carefully identified and deleted from the list. Particular attention has been given to features that, although unique within Hemiptera, seem more probably to represent some relict pre-hemipteran plesiomorphies than coccid autapomorphies (e.g., the structure of the antenna and some sense organs). The scale insects are thought here to be a monophyletic group. Within them, Putoidae is considered as ancestor of all neococcids, which comprise > 90% of scale insect species. The remaining 10% are represented by the diverse archeococcids; their interrelationships are obscure, but each of them bears at least some features of the scale insect ancestors; thus they should be an object of hemipterologists’ interest in tracing the phylogeny of the bugs.