The hypothesis that North Temperate Odonata can be categorized into spring or summer species by the predominant overwintering instars and the position and duration of the adult flight season was tested for 55 species in North Carolina. Over 3,000 larvae of these species, collected at a time of stable instar distribution (winter), were examined and the population structure determined for each species. The composition of the wintering populations varied from a single instar to (probably) the entire spread of instars, known for the species. The peak occurred in any one of the last four instars, depending upon the species. The spring vs. summer species classification is valid at high latitudes but breaks down at the latitude of North Carolina, where there is a continuum of variance from one type of life history to another.