Field studies on the tree hole mosquito, Aedes triseriatus were conducted at the Baltimore Zoo. Through larval surveys and ovitrap sampling the oviposition patterns, seasonal dynamics and dispersal of Ae. Triseriatus were studied in 4 biotopes: forest, field, lawn, and penguin exhibit. Natural sources of this species existed exclusively in the forest and were represented by 164 beech tree holes per hectare. Ovitrap sampling indicated that Ae. triseriatus was not strictly confined to the forest where natural development sites exist. Oviposition activity was highest in the beech forest, was less common in the lawn and open field biotopes and was rare at the penguin exhibit.