Scientific literature indicates potential for using plant extracts to control arthropod pests thereby decreasing the amount of synthetic chemicals introduced into the ecosystem. The research presented below tested several control candidates in a field settig to determine if selected oils can be used to control grasshopper infestations. Two field studies tested the effects of five plant extract oils on grasshopper pests in southern Alberta: Rosmarinus officinalis, Cedrus deodorata, Melaleuca alternifolia, Eucalyptus globulus, and Azadirachta indica. Grasshopper abundance increased in the first study in all plots and decreased in the second study in all plots. A third study was conducted in a greenhouse where grasshoppers were treated with two concentrations of cedarwood and rosemary oil and were monitored for eight days for mortality and behavioural effects. A non-target study was conducted in order to determine if control candidates would negatively affect other beneficial arthropods. Cedarwood, neem oil and carbaryl bait were tested on the mortality of Carabidae and Phalangiidae using pitfall trap sampling. / viii, 98 leaves : ill., maps ; 29 cm.