New plant growth may become distorted or stunted before predators and parasites decimate the aphid population. The greatest damage may be from the sticky, sugary aphid excrement called honeydew. Honeydew may fall on automobiles or furniture below infested trees. Adelgids, psyllids or phylloxeras are closely related insects that resemble aphids. The adelgids and phylloxeras frequently induce infested host plants to form galls in which the insects live.
Aphids are present on most plants, generally at non-injurious levels.
The honeydew excreted by aphids may be useful for identifying aphid populations. Before applying any insecticide treatments, search the aphid colonies for these natural enemies. High numbers of these beneficial insects usually indicate that aphid problems are being controlled without your intervention. This information is for educational purposes only. References to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned.