This study was conducted to monitoring the insecticidal susceptibility of Western flower thrips, Frankliniella occidentalis,damaging the horticultural crops in Gyeonggi area. Neonicotinoid insecticides, especially acetamiprid SP, clothianidin SC,imidacloprid WP and thiacloprid WG were not toxic to F. occidentalis collected from horticultural crops. Excepting theinsecticide of spinosin or pyrrole class, there was a little class of insecticides for the effective control of F. occidentalisin horticultural crop areas. Considering all the results in this study, spinosin insecticides including over 4 and 10% ofspinetoram and spinosad, and pyrrole insecticide including over 5% of chlorfenapyr should be recommended for the effectivecontrol of F. occidentalis, damaging the horticultural crops in Gyeonggi area.

• Young-Su Lee(Department of Agricultural Biology, Gyeonggi-do Agricultural Research and Extension Services)
• Hyun-Ju Lee(Department of Agricultural Biology, Gyeonggi-do Agricultural Research and Extension Services)
• Soon-Sung Hong(Department of Agricultural Biology, Gyeonggi-do Agricultural Research and Extension Services)
• Chang-Sung Kang(Department of Agricultural Biology, Gyeonggi-do Agricultural Research and Extension Services)