The first sign of infestation is the appearance of isolated, 
minute, white wooly dots on the bark, usually near the base of the 
tree. As the infestation increases, the dots appear in the form of 
thin vertical lines and then as solid patches. On heavily infested 
trees the trunks (fig. 26) and lower sides of branches may be 
completely whitened. 
F-502240 
FIGURE 26.—Infestation of the beech scale 
Cryptococcus fagi, on the trunk of beech. 
Light infestations are not particularly injurious but when they 
increase to an intensity of about 100 scales per square inch the 
outer layer of bark is killed and turns brown. Depressions or pits 
form in bark tissues around these wounds and are frequently 
numerous on young trees. The death and shrinkage of groups of 
cells within feeding areas also causes ruptures in the bark. How- 
ever, this usually does not happen until 2 to 5 years of infestation. 
A fungus, probably Nectria coccinea var. faginata, also probably 
introduced, gains entry through these ruptures (223). It pene- 
trates to the cambium and sapwood, killing tissues and interfering 
with the conduction and storage processes of the tree. Red fruit- 
ing bodies produced by the fungus become so abundant on 
severely infected trees that large areas on the trunk turn red. 
This leads to death of irregular-shaped areas of bark. Individual 
fungal lesions also coalesce and girdle the trunk, leading to crown 
deterioration and finally, the death of the tree. The fungus is 
entirely dependent on the scale for its incidence and spread. 
Enormous quantities of beech have been killed and the only 
known way to prevent such losses is through the cutting and re- 
moval of infested trees (646). This is true despite the fact that 
some degree of natural control is provided by the twice-stabbed 
lady beetle and that winter temperatures of —35° F. are highly 
effective in the control of infestations exposed above the snow 
line. 
The European elm scale, Gossyparia spuria (Mod.), an intro- 
duced species, occurs over most of southern Canada and the 
United States, wherever its hosts, native or European elms, grow. 
The adult female is oval and olive green to reddish-brown, has a 
white, waxy fringe along the body margin, and is about 114 to 
114 mm. long. The males, some of which are winged, are much 
smaller. Trees of all ages are infested. 
The winter is spent in bark crevices on the trunk and large 
branches. Eggs are laid from spring to midsummer, and newly- 
98 
