Recent investigations on the sesquiterpene-rich Amyris (Amyris balsamifera L.) and Siam-wood (Fokienia hodginsii L.) essential oils revealed significant arthropod repellency and toxicity responses. Amyris essential oil and one of its major components, elemol, were evaluated in laboratory bioassays and identified as effective mosquito repellents, specifically characterized by high levels of contact and minimal spatial repellency. Mosquito responses to catnip (Nepeta cataria L.) essential oil are characterized with high spatial activity, but lack significant contact repellency. Sampling within the staticair bioassay chamber with solid-phase microextraction provided measurements of the relative concentration and distribution of volatiles. These results supported the differences observed in repellency between essential oil treatments. Essential oil mixtures containing both spatial (catnip) and contact (Amyris) repellents were made and showed high levels of residual control via both modes of action. Siam-wood essential oil scored high in both spatial and contact efficacy against mosquitoes. Observations during this study included signs of toxicity. Two of the primary components of Siam-wood essential oil were tested for 24-hour house fly (Musca domestica L.) topical mortality. Transnerolidol and fokienol were found to possess similar insecticidal activity (topical LD50 values ranged from 0.17-0.21 µmol/fly). Amyris essential oil was selected for additional testing with brown dog ticks (Rhipicephalus sanguineusLatreille) in a 'barrier' repellency assay. Individuals were observed repeatedly avoiding and moving away from surfaces treated with Amyris essential oil.