History and distributionEdit
Beech bark disease has been recorded as affecting common beech trees, Fagus sylvatica, in Europe since before 1849. Until 1914 it was thought that the beech scale insect itself was responsible for the disease. Subsequently it was discovered that a fungus, then identified as Nectria ditissima, was in fact killing the trees infested by the scale. Around 1890 the scale insect was accidentally introduced into Nova Scotia. By 1932, the scale and its associated Nectria fungus had spread to many areas of the Maritime Provinces and parts of eastern and south central Maine. It continues to spread in North America and is now found in Quebec, New England, New York, New Jersey, Pennsylvania and West Virginia. Attempts are being made to discover the geographic origin of beech scale in order to try to identify any natural enemies that might hold promise for its biological control. From these studies and associated ribosomal DNA analysis, it seems likely that the pest originated in the region of northeast Greece, northern Iran, the Caucasus and the Black Sea drainage basin on the host beech subspecies F. sylvatica orientalis
Adult scales are elliptical and about one millimetre long and are covered by a cream colored, cottony wax secretion. They have reddish-brown eyes, no wings, rudimentary antennae and legs, and numerous minute wax-secreting glands. The stylet through which they suck sap can be up to two millimetres long.