The adult female oystershell scale is up to four millimetres long, elongated, tapering to a point at the posterior end and often slightly curved, somewhat resembling a mussel shell.

[2] The crawler moults twice before becoming an adult female, forming a protective scale from larval exuviae and secretions.

[1] Over one hundred and fifty host plant species are known for the oystershell scale including members of the families Aceraceae, Betulaceae, Caprifoliaceae, Celastraceae, Elaeagnaceae, Grossulariaceae, Hydrangeaceae, Juglandaceae, Oleaceae, Pyrolaceae, Rosaceae, Salicaceae and Tiliaceae.

Apart from forest trees and ornamentals, the oystershell scale is a pest of apples, pears, plums, peaches, apricots, mulberries and currants.

[2] In some parts of the world, populations are controlled to a certain extent by the oystershell scale parasitoid, Aphytis mytilaspidis[3] and the ladybird Chilocorus bipustulatus.