FERA plant health officer Richard McIntosh said the large find would raise awareness in the trade and asked importers to be vigilant.
"Tobacco whitefly is a pest we are concerned about. We're keen to keep it out. Poinsettia is a plant at risk of transporting the pest and there is a particular risk at this time of year as large numbers are coming in for the Christmas market," he said.
McIntosh added that the pest may have been found on plants at a distribution centre, wholesaler or retail site and compensation was a commercial matter.
FERA carried out a review on retaining protected zone status against Bemisia tabaci in early 2011, with support from the trade to retain the status.