They are found living on downy birch trees (Betula pubescens) where they feed and multiply on the buds and leaves by sucking sap.

The downy birch aphid has a pale green body, lightly dusted with bluish wax particles, membranous wings and long legs.

Downy birch trees have been introduced into North America and the aphids have accompanied them there, arriving in about 1847.

The aphids are preyed on by ladybirds and are parasitized by certain species of wasp which lay their eggs in young nymphs.

At this time the tree is transferring organic products out of the leaves (which will soon be shed) to the trunk and roots for storage.