Identification

• Apple trees are prone to infestation from the woolly apple aphid. The pests have red to purple bodies that are entirely covered with a white woolly and waxy coating. Woolly apple aphids mostly infest woody tree areas like the trunk. Pest-infested areas resemble mold.
  
  

Damage

• Woolly apple aphid damage to trunks and limbs leads to the growth of galls or swollen tree tissues. Damage to root areas of the trees stunts tree growth. Aphid feeding on foliage causes yellow spots on leaves. The insects create their colonies in tree wounds and axils of foliage.
  
  

Control

• Apply insecticidal soap or horticultural oil to infested trees. In areas with known serious infestation of pests, try to use resistant apple varieties. You can also introduce natural predators like the parasite Aphelinus mali in trees as a biological control option.