Insecticidal effect of aqueous and ethanol extracts of dried leaves of Ambrosia artemisiifolia L., Piper auritum Kunth, and Taraxacum officinale F. H. Wiggwere determined on developmental stages of potato/tomato psyllid, Bactericera cockerelli (Sulc). When aqueous extract at 0.2 g/ml was applied to psyllid nymphs, A. artemisiifolia extract was most toxic, P. auritum was moderately toxic, and T. officinale was slightly less toxic. Ethanol extract of A. artemisiifolia killed more than 50% of 2^nd, 3^rd, and 5^th instar nymphs treated with 0.001, 0.01, and 0.1 g/ml, respectively. P. auritum was effective on 3^rd and 4^th instars and T. officinale on 5^th and 3^rd instars at 0.01 and 0.1 g/ml, respectively. Ethanol extracts of the three plant species killed 50 to 60% of adults with 0.1 g/ml and 30 to 45% with 0.01 g/ml. Extracts of Argemone mexicana L., Azadirachta indica A. Juss, Petiveria alliacea L., and Tagetes filifolia Lag. were evaluated on 4^th and 5^th instar nymphs. Ethanol extract of leaves of A. mexicana at 0.2 g/ml killed 100% of 5^th instar nymphs at 24 hours and 93% of 4th instars at 72 hours. A. indica, P. alliacea, and T. filifolia at 0.2 g/ml killed 85, 88, and 87%, respectively, of 5^th instar nymphs.