This research focuses on two container breeding mosquito species; Ochlerotatus triseriatus and Ochlerotatus hendersoni. Formerly considered variations of a single species, these species share many similarities in natural history, behavior, appearance and even genetics. The degree to which the two are morphologically distinct is dubious based on previous work, as is the consistency, cause, and degree of vertical stratification of oviposition sites selected by gravid females. This work addressed these problems in several ways. Morphology of samples derived from 25 populations located across the United States were examined and compared at each life stage, and it was determined that traditional diagnostic morphological features are unreliable. Exceptions were egg surface morphology and conditional reliability of larval ventral brush number and anal papillae length ratio. Five rare natural hybrids were collected from sloped habitats and included in the morphological descriptions. Patterns of vertical habitat stratification by gravid females were examined in several populations, including allopatric and sympatric, as well as those located in complex landscapes such as flood prone and steeply sloped areas. Allopatric populations of O. hendersoni preferred basal habitats in contrast to those sympatric with O. triseriatus , supporting the theory that the former may oviposit in canopy habitats in order to avoid its more successfully competitive counterpart. Allopatric populations of O. triseriatus showed preference for basal larval habitats, and the species pair stratified in sympatric populations as expected. Populations sampled from sloped locations showed minimal difference in vertical stratification from non-sloped. No oviposition took place in basal habitats in either flood prone sampling location, while virtually all corresponding canopy oviposition was by O. triseriatus, again supporting competition avoidance theories among several alternate potential causes. Nearby upland locations resulted in typical stratification patterns. Habitat suitability models were developed for the presence of each species, the presence of hybrids, and the presence of habitat similar to the flood prone sample locations based on the data gathered during the course of this work. Further inquiry into the phenomena observed at each location will be facilitated by these models.