-- The lecanium scales are distributed throughout the United States.
High scale populations severely reduce vitality, weaken the tree, and
cause branch or crown dieback. They have been of greatest concern to
shade and ornamental red and white oaks.
Insect (figure 39). -- The body of the adult female is circular
to ovoid, strongly convex or tortoise-shaped, and about .2 to .3 inch
(4 to 7 mm) in diameter. Young females may be tan or mottled with black,
but older females are reddish or dark brown. After their eggs hatch,
the female body shells remain loosely attached to the bark. Scales commonly
overlap and encircle portions of infested twigs.
the Injury. -- Trees of poor vigor or with branch and crown dieback
should be examined closely for scale insects. Lecanium scales are most
prominent on twigs during the spring and early summer.
-- Eggs are produced underneath the female in late spring. Eggs hatch
in early summer and the immature insects seek feeding sites on the underside
of leaves. In late summer, they migrate to twigs where they overwinter.
They complete their development in the spring. There is usually one
generation per year.
-- Parasites and predators are effective in controlling infestations.
However, insecticides are often used and are most effective against