Recently I have been asked for recommendations to manage whiteflies on poinsettias in color. Growers are understandably hesitant to make applications for fear of phytotoxicity to bracts. Yet if whiteflies are around you need some control. I polled many colleagues who also work in greenhouse pest management for their recommendations. Here I have compiled the consensus of their comments. Talstar Flowable (bifenthrin), Endeavor (Pymetrozine), and Sanmite (Pyridaben) were all reported to leave noticeable residue on bracts but not phytotoxicity. Avid (Abamectin) was reported by some to have a slight bronzing effect on bracts at the high rate. Safari (dinotefuran), Judo (spiromesifen), Imidacloprid, and TriStar were not reported to leave residue or cause phytotoxicity. However, if you have found imidacloprid to have low efficacy you may have some level of resistance in your greenhouse population. In this case I would stick with Safari or Judo.
There are hundreds of poinsettia varieties and it is possible any product will negatively affect one variety or another. Thus it is always recommended that you test a product on a few plants and wait a couple days before spraying the whole crop. Some product labels advise against or prohibit application to poinsettias or poinsettias in color. Be sure to check any label before application.