Infestation of Woolly Aphids

Woolly aphids are insects residing on various trees and shrubs, and they earn their name from their distinct feature – a white, wool-like waxy coating covering their bodies. During the late summer months, one may encounter dense clusters of these aphids on the twigs and branches of hawthorn and...

, and Administrator

2025 September 13 . 5:31 AM

2 min read

Infestation of Wooly Aphids: Impact on Flora and Fauna

Infestation of Woolly Aphids

The Iowa State University Entomology Department, located in Iowa, is the institution that identifies insects and provides valuable information on pest food, development, and management. One common pest they often encounter is the woolly aphid.

Woolly aphids are small insects that feed on sap from plants, their bodies covered with a white, fluffy wax resembling wool. They can be found on various trees and shrubs, including maple trees and hawthorn and crabapples.

While the sap loss from aphid feeding is usually not significant to the plant, control measures may be necessary in some cases. Infestations of woolly aphids are sporadic and can vary significantly between trees, varieties, and locations.

Pruning and removing heavily infested stems and water sprouts can help manage woolly aphid populations. In some cases, parasites, predators, and heavy rainfall can also help reduce their numbers. For a more direct approach, using a forceful stream of water from a garden hose can dislodge woolly aphids.

If you suspect you have woolly aphids on your trees or shrubs and need confirmation, you can submit a sample to the Iowa State University Plant & Insect Diagnostic Clinic. However, it's crucial to check the current forms, fees, and instructions on their website before doing so. The clinic identifies insects and provides information on what they eat, life cycle, and pest management.

If you live outside of Iowa, it's recommended to contact the Iowa State University Plant & Insect Diagnostic Clinic before submitting a sample. Contact information for each state's diagnostic laboratory for U.S. residents is also available.

Earlier in the season, there were woolly aphids of another species on the leaves and shoots of maple trees. In late summer, colonies of woolly aphids can be seen on hawthorn and crabapple trees. While these infestations can be alarming, they are generally more alarming than damaging, especially late in the season.

Spraying home garden insecticide for woolly aphids is rarely justified, but can be done when the aphid population is increasing or the plant is under other stresses. However, it's important to note that this premature leaf drop does not affect the overall vigor of healthy trees.

In some cases, infested leaves may droop or shrivel and drop prematurely. This does not necessarily indicate a severely affected tree. The overall vigor of healthy trees can withstand such minor setbacks.

In conclusion, while woolly aphids can be a nuisance, understanding their habits and taking appropriate measures can help manage their populations. For more information and assistance, the Iowa State University Entomology Department's Plant & Insect Diagnostic Clinic stands ready to help.