These aphids, which suck the sap of alder trees, are covered with fluffy white "wool" made of a waxy substance when they are adults. The fluffless, wingless earlier life stages feed on maple trees (Silver Maple (Acer saccharinum) is reported to be most common) and so they are also known as maple blight aphids. They require alders and maples at different stages in their life cycle. As they change to adult form, they grow wings and use them to fly from the maple host trees to the alder alternate hosts, looking like bizarre flying white puffballs as they wing their way from host to host. Compare with the similar Beech Blight Aphid (Grylloprociphilus imbricator), which feeds on American Beech trees.

These true aphids, in the family Aphidae, look superficially similar to the woolly adelgids, such as the Hemlock Woolly Adelgid (Adelges tsugae), in the family Adelgidae.

Woolly Alder Aphids are one of the food sources for the carnivorous caterpillars of the Harvester butterfly (Feniseca tarquinius).

Madison Co., NC 4/9/2012.