The biocidal activity of three steam distilled wood essential oils-incense cedar, Calocedrus decurrens (Torr.) Florin; Port-Orford-cedar, Chamaecyparis lawsoniana (A. Murr.) Parl.; and western juniper, Juniperus occidentalis (Hook)--were evaluated against adult Aedes aegypti (L.) (Diptera: Culicidae) and Xenopsylla cheopis (Rothchild) (Siphonaptera: Pulicidae) and nymphal Ixodes scapularis Say (Acari: Ixodidae). In vitro laboratory bioassays were conducted to establish baseline dose-mortality data through 24 h. Incense cedar heartwood was the most toxic to all three vector species followed in order of activity by western juniper and Port-Orford-cedar based on LC50 and LC90 values. Ae. aegypti were substantially more susceptible to the oils than either I. scapularis or X. cheopis.