In their natural habitat, poinsettias bloom according to day length. In their native locale, they are actually a large growing, woody shrub with a height above 10 ft. While most people are not sensitive to the sap, it can cause a mild skin irritation. They can be found either on the plant or soil surface. The adults are more of a nuisance, while the larvae tend to feed on plant tissue.
Mealybugs are serious pests of poinsettias.
These insects are soft-bodied and appear as a cottony mass, usually in the axis of the leaves. Most serious diseases that affect poinsettias are soil-borne and are primarily fungi. Species of Rhizoctonia, Pythum and Phytophthora are the most common diseases. The easiest methods for controlling these disease organisms are by sanitation and periodic soil drenches with a recommended fungicide. If plants get too tall and you want to propagate them, take leafy cuttings during early to mid-August.