This article is the first report on the phytophagous activity of C. hesperidum on hemp plants grown in greenhouses in Kentucky, USA. Hemp plants were grown in a greenhouse where ornamental plant species were previously grown but were not present at the same time. Coccus hesperidum may have been carried by wind because greenhouse windows were kept open. Coccus hesperidum successfully fed and reproduced on the stems and leaves of hemp. After 2 wk a single plant, kept in laboratory for further studies, died as a consequence of the feeding damage caused by a large population of scales. As hemp is expanding to different production areas, C. hesperidum might be a potential pest for hemp grown in greenhouses. The surveillance and early detection of C. hesperidum will contribute to the production of healthy hemp plants to be planted in open fields, especially in southern states of the USA.