Family- Sesiidae

The peachtree borer kills more peach trees in the United States than any other insect. In the north central states, where there is a high incidence of valsa canker and winter injury, the lesser peachtree borer probably ranks higher as a general pest than the peachtree borer. However, control programs for the peachtree borer must begin the year young trees are planted and must continue for the life of the planting.

Egg: The egg is about 0.65 mm long, chestnut brown or reddish brown, ellipsoidal and slightly flattened at the sides, with light-colored, waxlike, elevated lines that form hexagonally sculptured areas on the egg surface.

Larva: The larva is white or cream colored with a yellowish brown to dark brown head. It has three pairs of segmented thoracic legs. Abdominal prolegs are present on the third, fourth. fifth, sixth and last abdominal segments. All of the prolegs have two rows of crochets (hooks) except the last pair, which have one row of crochets. The larvae vary in size from 1.6 mm for newly hatched larvae to 38 mm for full-grown larvae.

Pupa: When full grown, the larva leaves the burrow under the bark and constructs a cocoon made of silken threads and bits of wood or frass. Approximately 90 percent of the cocoons are found in the top layer of soil within 2 inches of the tree near the ground line. In infested trees, cocoons may be found in the burrows. Female pupae average 19 mm long (slightly larger than male pupae), are darker and show an orange band on the fourth abdominal segment; male pupae have two rows of spines. The length of the pupal stage varies from 18 to 30 days, depending on temperature.

Adult: The adults are clear-wing moths (only the veins and edges are colored). The females are slightly larger than the males – the wing span of the female is 30 to 33 mm and that of the male, 25 to 28 mm. The general color of the moth is dark steel-blue. The fourth or fourth and fifth abdominal segments of the female’s body are covered by bright orange scales. The female’s body is usually more robust than the male’s, especially when filled with eggs. In the male, various areas of the third, fourth, fifth and sixth abdominal segments may be fringed with white or yellow scales. The slender abdomen of the male terminates in a wedge-shaped tuft of scales tipped with white.

The peachtree borer is a major pest of peaches but sometimes causes serious damage to cultivated cherry, plum, apricot, nectarine and ornamental shrubs. The peachtree borer has been reported in al fruit-growing areas of the United States and Canada.

The principal damage is done by the larvae, which feed on the cambium, or growing tissue, and inner bark of the tree. Most of the larval activity is confined to the trunk area from a few inches above to 6 inches below the ground line. Larval feeding may completely girdle and kill young trees. Older trees are less likely to be girdled but are often so severely injured that their vitality is lowered so that other insects, diseases and environmental conditions can complete their destruction.

Borer-infested trees bleed or exude gum during the growing season. The frass of sawdustlike excrement in the exuded gum indicates the presence of borers. Trunk injury by diseases or environmental conditions will usually produce clear gum.

Warm, sunny days favor the emergence of adults from their pupal cases; darkness retards emergence. Moist soil also favors adult emergence. The greatest emergence usually occurs the day after a rain.

The peachtree borer overwinters as larvae on or under the bark of trees, usually below the ground level. The larvae become active and begin to feed on the inner bark when the soil temperature reaches 50 degrees F. When full grown, the larva constructs a cocoon and pupates, usually during late May and June. Moth emergence begins in early July and continues into September. The moths mate immediately after emerging and the female begins to lay eggs within 30 minutes.

The majority of eggs are deposited the day of emergence and mating. Eggs may be deposited singly or in bunches on all portions of the tree, but the majority – up to 85 percent – are deposited around the bases of the trees or on the trunks. Each female deposits between 200 and 600 eggs during the six or seven days she is alive. Egg deposition occurs between 9 a.m. and 4:30 p.m., with the majority of eggs deposited the afternoon of the day of mating. Females lay few eggs after the third day.

The egg incubation period averages nine to 10 days during warn summer days and up to 15 days during colder periods. The young larvae bore into the bark at the base of the tree. Once beneath the bark, they feed on the cambium and inner bark of the tree. Generally only one generation occurs each year in the north central states. Some larvae, however, may require two years to complete development.

Examine the bases of trees for frass or sawdustlike excrement in the exuded gum. Place pheromone traps in trees early in the season. Depending on location, this may vary from early May to late June.

Identification of the peachtree borer adult male is important; pheromones are not specific for this pest, and other clear-wing moths such as the dogwood borer and lilac borer may be caught in pheromone traps meant for the peachtree borer. Note that the lesser peachtree adult borer is not attracted to the same pheromone traps as the peachtree borer; pheromones for the former are specifically designed to trap only that species.

A hydraulic gun is used to direct an effective chemical at the base of the tree at low pressure before the eggs hatch. One or two years’ protection can be provided to newly planted trees by dipping the trunk and roots into an effective chemical solution before planting. The young trees should be inspected for crown gall before using the dip method. Pheromone traps are used to time sprays.