of Rhode Island GreenShare Factsheets
The peachtree borer, a native insect, is a major pest
of stone fruits in the United States and Canada. Prior to the
introduction of the peach, it lived on native wild cherries
and plums. The majority of peachtree borers have a one-year
life cycle, but some larvae may require two years to complete
The adults are clear-winged, day-flying moths which, to
the casual observer, are often mistaken for wasps. The sexes
are strikingly distinct. The female is steel blue with an orange
band on the fourth and sometimes also fifth abdominal segment.
The forewings are opaque, covered with blue scales; the hind
wings are transparent. The wingspread is 35-38 mm (1 3/8 -
1 1/2 in). The male is smaller, with a wingspread of 27-30
mm (1 1/16 - 1 1/8 in). Both pairs of the males' wings are
clear except for the margins and a line across the forewing.
The blue abdomen is marked with three or four narrow yellow
stripes. Peachtree borer eggs are oval, reddish-brown, and
are deposited singly or in small groups on the trunk, lower
scaffold limbs, or on debris or soil near the base of the tree.
Peachtree borer larvae are white or cream-colored with a yellowish-brown
to dark brown head. When half to full grown, the prothoracic
and anal shields become yellow to dark brown in color. Like
other lepidopterous larvae, they have three pairs of jointed
thoracic legs plus prolegs on the third, fourth, fifth, sixth
and last abdominal segment. There are seven larval instars,
varying in size from 1.6 mm to 38 mm (1/16 in - 1 1/2 in).
Adult emergence commences early in July, peaks in August,
and may extend into October. Mating occurs soon after emergence.
Several hours later, egg laying begins. A female may produce
up to 800 eggs, the average being about 400. Ovipositing females
seem to be attracted to trees previously infested by the peachtree
borer or to trees on which mechanical injury has occurred.
The moths die a few days after the short period of egg deposition
ends. The incubation period varies with the temperature and
averages about 10 days. First egg hatch occurs in mid-July.
Upon hatching, the larvae immediately start burrowing into
the bark, usually entering at a crack or wound near the soil
surface. The larvae feed on the cambium or growing tissues
and tunnel between the inner bark and the sapwood. The larvae
normally attack the tree trunk between 76 mm (3 in) below ground
to 254 mm (10 in) above ground. Some of the earlier-hatching
borers are nearly mature by fall, but most are only half-grown.
The larger larvae hibernate in their burrows beneath the bark,
while the smaller larvae usually pass the winter on the bark
under a thin silken covering or hibernaculum.
Feeding resumes with the advent of warm
weather in April and May. Prior to pupation, the mature larvae
the soil, where they construct silken cocoons containing particles
of chewed-up bark, frass and soil particles. The cocoons are
elongate, brownish to sand-colored capsules averaging about
22 mm (7/8 in) long. They are usually situated in an upright
position just beneath the soil surface. Within the cocoons,
the larvae pupate into dark brown to black pupae measuring
about 14 mm (9/16 in) long. The pupae possess stiff spines
on their backs which assist them in working themselves out
of the cocoons. The combined period of cocooning and pupation
averages about 28 days.
Injury is caused by the larvae feeding on the cambium
and inner bark of the trunk close to the soil level. Larger
roots are occasionally attacked as well. Areas attacked often
have masses of gum, mixed with frass, exuding from the bark.
All ages of trees are susceptible to injury. Young trees are
at times completely girdled and subsequently die. Older trees
are often so severely injured that their vitality is lowered
and they are rendered especially susceptible to attack by other
insects or by diseases.
From early July through October, look on trunk and lower
scaffolds. Peachtree borer flight can be monitored with pheromone
traps. Look for the eggs from early July through October on
the trunk, lower scaffold or at the base of the tree. The larvae
can be found year-round beneath the bark in a wound identified
by an exuding mixture of frass and gum. The pupae are found
from early June through October within cocoons in the soil.
The peachtree borer can be controlled by thorough, well-timed
insecticide applications. An orchard spray directed against
the adults will also control other pests present at the time.
Peachtree borer pheromone trap catches can be used to time
these sprays. Another treatment directed at the larvae calls
for the application of a trunk spray anytime between July 20
to August 1. Young peach trees can be protected for a year
or more by dipping the roots and crowns in a systemic insecticide
solution prior to planting.
Adapted from S. E.
Lienk, Cornell Cooperative Extension, 1999
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
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Be sure that the pesticide you intend to use is registered for
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The user of this information assumes all risk for personal injury
or property damage.
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
of Rhode Island Cooperative Extension provides equal program