-- Phylloxerids are very small, aphid-like insects that attack the foliage
and buds of red and white oak trees of all sizes. Heavy infestations
stunt and weaken the trees. The distorted foliage mars the beauty of
Insect (figure 35a). -- Phylloxerids are small .01 to .02 inch (0.3
to 0.6 mm) long, aphid-like, lack cornicles and usually spiny in appearance.
Winged forms have reduced wing veination. They are usually found in
Injury (figure 35b). -- Buds and young developing leaves (undersurface)
on terminals and branch ends are attacked, causing the leaves to curl
and twist. Growth may be reduced or stopped. Mature and nearly mature
leaves are unaffected. Damage occurs during spring and early summer.
-- The biology of this pest is not well known, but overwintering occurs
as eggs in bark crevices. Eggs hatch during the spring. There appear
to be several generations per year.
-- Natural controls usually keep damage to a minimum. Ornamentals may
require chemical control.