The effectiveness ofLiothrips urichiKarny introduced to control the noxious weedClidemia hirta(L.) D. Don was studied at three sites on Oahu, Hawaii. VegetativeC. hirtainfested withL. urichishowed greater mortality after 1 mo and significantly shorter internode diameters among the survivors at 4 mo than uninfested plants.L. urichihad no effect on plant height in the field but stunted the growth of young pottedC. hirtain greenhouse studies and caused a significant increase in terminal leaf drop. No effect on production of floral buds, flowers, or berries occurred at any field site over 11 mo.L. urichiwas restricted to sunny or partly sunny sites and never occurred in heavily shaded areas. Higher thrips infestations occurred during the fall and winter and lower infestations during the summer. Percentage of damaged tips also fluctuated seasonally, but the degree of damage to individual leaves was not seasonal.