Woolly beech aphid is a medium–sized (2-3 mm) elongated, yellow green aphid. Adults are covered with a water repellent waxy coating, which younger stages lack. They are sometimes misidentified for mealybugs, because of their woolly appearance. The antennae are shorter than the body. Winged stages have a wax-covered abdomen. The aphid overwinters as an egg on young beech tree twigs.

Woolly beech aphid damage and distribution

Woolly beech aphids prefer the underside of young beech tree leaves. Their feeding causes leaf curling and yellow spots on the upper side of the leaves. Young shoot development is decreased and heavy infestation on young plants can even cause plant death. The aphids are often found in young tree plantings. Woolly beech aphids produce large amounts of honeydew, which acts as a growth medium for black sooty mold fungus, which in turn hampers photosynthesis.