Beech Scale: Appearance, Territory, Damage, and Life Cycle

Latin Name: Cryptococcus Fagisuga

Appearance: Beech trees of the species Fagus are infested by the felted scale bug Cryptococcus fagisuga, sometimes referred to as the beech scale or woolly beech scale. In Massachusetts and Maine in the 1930s, the beech scale (Cryptococcus fagisuga Lindinger) was discovered for the first time in the United States. This European insect feeds on American and European beech by penetrating the smooth bark with its long, needle-like, sucking mouthparts (or stylets), which stay stationary throughout the bug’s existence.

Hosts Plants: The natural host is thought to be the oriental beech (F. orientalis). The beech species F. sylvatica, native to Europe, and F. grandifolia, native to North America, serve as hosts.

Territory: Beech scale is found in North America from Nova Scotia to central Pennsylvania, with pockets of infestation in West Virginia, North Carolina, and Michigan, although it is still spreading. From the United Kingdom to Iran, the scale may be found in Eurasia. Although it may be found all throughout Europe, it is thought that this is no longer its original range. The Caucasus Mountains, which may have been part of this insect’s original habitat, have the highest mitochondrial haplotype diversity of all regions so far investigated.

Damage Insect Cause: Individual scales are around 1mm long, although infestations are normally discovered by the grey-white waxy powder produced by colonies. Although no honeydew is generated and there is no direct harm, damaged trees may become more prone to beech bark disease, a combination of the scale and a canker fungus. Control is not required because this insect normally causes minimal direct harm to trees and may be viewed as part of the insect life that beech trees can maintain.

Life History and Habits: Each year, one generation of the beech scale is produced. In July, adults deposit light yellow eggs on the bark before dying. Eggs are strung together in threads of four to seven eggs. From late summer to early winter, the eggs hatch. Crawlers or nymphs are young scales that hatch from eggs. Crawlers, unlike adults, have functioning antennae and legs and can move about.

When a crawler finds an appropriate spot on a host tree, it inserts its long, tube-like style into the bark and begins sucking sap from the tree. When a crawler starts feeding, it molts to the second stage. Crawlers in the second stage lack legs and are motionless. They secrete white wax, which gradually coats their body. Second-stage crawlers hibernate and molt to adulthood the following spring.