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Description: 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).
Life Cycle: 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 normally enter 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. Damage: 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. Monitoring: 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. Control: 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
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