The pecan phylloxera, _Phylloxera devastatris_ Perg., and the pecan leaf
phylloxera, _P. notabilis_ Perg., produce galls on the new growth of
pecans. Leaves, twigs and nuts may be affected.
The galls are conspicuous swellings, Figure 17, which attain a size of
from one-tenth to 1 inch in diameter. They are caused by a soft-bodied
insect which is closely related to aphids.
The winter is passed in the egg stage in crevices in the bark. In the
spring, the egg hatches and the tiny nymph feeds on the tender, young
growth, apparently secreting a substance which stimulates the plant
tissues to develop into galls.
After the nymph reaches maturity, a number of eggs are deposited inside
the gall. The young nymphs of the succeeding generation develop within
the gall, which splits open in 1 to 3 weeks, liberating them. Several
generations follow during the summer and fall, as long as there is fresh
young growth on the tree. From 4 to 5 weeks are required for each
generation[4].
_Control._—The dormant oil spray recommended for obscure scale control
will prevent the development of phylloxera. If dormant oil is not
applied, use 2 pints of nicotine sulfate plus 6 pounds of soap; 3 pounds
of 25 percent malathion wettable powder; or two and a half pounds of 10
percent gamma isomer BHC wettable powder per 100 gallons of water when
the leaves are one-third grown.