t this insect.
Three applications (the first on August 26 when the first girdled twigs
were observed and the others on September 9 and 23) of DDT, 4 pounds of
50 percent wettable powder per 100 gallons of water, or parathion, 3
pounds of 15 percent wettable powder per 100 gallons, gave complete
control. Further experiments will be required to determine the minimum
effective concentration of spray and the number of applications needed
for control. It is suggested that DDT be used for the control of this
insect until more information is available on how to handle and to use
parathion.

~Flatheaded apple tree borer.~ The adult beetle of the flathead apple tree
borer[25] (Fig. 12) deposits its eggs throughout the summer season,
preferably in the small grooves of bark on the unshaded portions of the
trunk of pecan and other trees. The borers (Fig. 13) hatch and tunnel
through the bark to the cambium layer. Young trees may readily be
girdled (Fig. 14).

[25] ~Chrysobothris femorata~ (Oliv.).

To avoid this insect as far as possible, orchard sanitation should be
practiced and the trees should be kept in a healthy condition. In some
plantings wrapping the trunks with paper or burlap to protect against
egg laying and maintaining low branches to shade the trunk have been
helpful. Cutting out the borers with a knife has also been resorted to;
trunk washes have likewise been used but have not been very effective.

~Buffalo treehopper and periodical cicada.~ Buffalo treehoppers[26] (Fig.
15) and the periodical cicada[27] weaken twigs by inserting their eggs
in them. The injured bark becomes roughened as it heals (Fig. 16), and
the growth of the limb is retarded.

[26] ~Ceresa bubalus~ (L.).

[27] ~Magicicada septendecim~ (L.).

Pruning of weakened twigs is recommended for wood injured by the cicada.
If treehoppers are a pest, clean cultivation will help. Cover crops of
cowpeas or clovers should not be planted. In preliminary tests two or
three applications of tetraethyl pyrophosphate (20 percent), 3/4 pint
per 100 gallons of water, have given promising results in controlling
the periodical cicada. The first application should be made after the
cicadas appear and the others as needed to prevent damage.

Observations on Effects of Low Temperatures in Winter 1949-1950 on
Walnuts and Filberts in Oregon and Washington

JOHN H. PAINTER

Horticulturist, United States Department of Agriculture, Agricultural
Research Admin