Control. Spray trunks of trees with 2% DDT-xylene emulsion in
spring, or apply a poisoned oil, 1/4 pound sodium arsenite dissolved in 5
gallons of water, to which is added 1 quart of oil. Avoid planting streets
exclusively to locusts; interplant with other types.
PEACH TREE BORER (Sanninoidea exitiosa).
Chiefly a peach menace, found
also on cherry, plum, apricot. Masses of amber jelly or gum exuding
from peach trunks near the base are an almost sure sign of borers at
work. They are white with brown heads, up to an inch long, and they
burrow in the bark from 2 or 3 inches below ground to 10 inches above.
Trees are severely weakened, sometimes killed. The worms pupate in dirt
and gum-covered cocoons at the opening of their burrows, or on the soil.
Blue-black moths with clear hind wings come out in July, August, or
September to lay eggs on bark or in soil cracks. In 10 days the young
larvae start working into the bark.
Control. The time-honored method-still good-is to ring the soil
around the tree with paradichlorobenzene crystals (1/2 ounce for trees
under 3 years, 3/4 ounce for trees 3 to 6 years, 1 ounce for older peaches)
placed between 1 and 3 inches away from the trunk and covered with
several shovels of earth to confine the gas. Exact dosage is important for
tree safety and right timing for control. Treatment should be done in
the fall after the young borers are in the tree but while soil temperature
is still above 60 °F. This is September 20 to October 1 in northern New
Jersey and October 15 to 20 in southern Georgia. Remove the soil mound
a month or so later. A newer recommendation is to spray trunk, crotches,
and limb bases thoroughly with DDT in July, repeating at 3-week intervals.
The LESSER PEACH TREE BORER (Synanthedon pictipes)
damage, but the larvae work in the upper part of the trunk and larger
branches. DDT is not so effective as it is for the peach tree borer; parathion is used in some commercial orchards.
RHODODENDRON BORER (Ramosia rhododendri).
When whole branches of
rhododendron, laurel, or azalea die back look along the trunk for
borer holes, with or without sawdust protruding (Figure 15C). The grub
is yellow white, about 1/2 inch long; the adult is a clear-winged moth
with black and yellow abdomen; the eggs are laid in June on twigs and
Control. Inspect shrubs frequently; cut out branches below the part
infested; paint trunks with DDT in spring before egg-laying; inject nicotine or lindane paste into holes showing fresh sawdust.