While the tree can withstand heavy populations of the aphids, feeding on the lower surface of the wide leaves, the primary complaint is the heavy production of honeydew. With large aphid populations the effect is to have the honeydew “raining” down from the tree, coating all surfaces below with a solid, sticky layer of the material. Since tulip trees are favorites along sidewalks and in parks this creates problems for cars and people in the area.
Control is only necessary where the honeydew is creating a problem, in which case a foliar spray with a labeled insecticide, targeting the undersides of the leaves, will be effective. A soil application of imidacloprid, applied in late winter, will also effectively kill the feeding aphids.