Taxonomy

Domain	Eukarya
Kingdom	Animalia
Phylum	Arthropoda
Subphylum	Hexapoda
Class	Insecta
Subclass	Pterygota
Infraclass	Neoptera
Superorder	Holometabola
Order	Lepidoptera
Superfamily	Sesiodea
Family	Sesiidae
Subfamily	Sesiinae
Tribe	Synanthedonini
Genus	Synanthedon

Scientific Name

Synanthedon pictipes

Common Name

lesser peachtree borer

Hosts

Peach, plum, cherry, beach plum, black cherry. Peach is the major cultivated plant host (Bobb 1969). Plum, cherry, and other cultivated stone fruits are attacked as well (Engelhardt 1946). Principal native wild plants attacked are cherry and plum, which may serve as an infestation reservoir for spreading to cultivated plants (Beutenmuller 1901). Serviceberry and chestnut have also been mentioned as hosts (Beutenmuller 1901) but are questionable (Engelhardt 1946).

Range

Eastern half of Canada and the United States westward to Minnesota in the north and eastern Texas in the south. Reported as far west as the Rocky Mountains and Pacific Coast but doubtful (Engelhardt 1946).

Description

Adult

Black clearwing moth with a metallic sheen and whitish yellowish markings on head, thorax, and narrow band on abdomen (Engelhardt 1946). Wings transparent and span 18 to 25 mm. Males and females similar but male more slender with finely tufted antennae.

Egg

Small, about 0.4 by 0.6 mm, reddish brown and very hard; chorion keeps shape after eclosion.

Larva

Newly hatched larvae small and difficult to see, especially in bark crevices of trees (Bobb 1959). Twelve-day-old larvae measure 2.5 to 5.0 mm long and reach 20 mm when grown (King 1914). Cocoons are just beneath the bark or near debris around the wound (Bobb 1959).

Biology

Moths emerge over the entire growing season, peaking in spring and early summer (Dupree 1972, King 1914, Rings 1960). Spring broods emerge from early April until late July; summer broods emerge early July through November (Bobb 1959). Females deposit eggs in broken bark, usually near wounds on vigorous trees. Eggs are deposited singly, but several female may lay large numbers of eggs in and around a wound. Eggs hatch in about 20 days during early season but require as few as 8 days later in the season (Bobb 1959). Larvae usually establish in bark cavities around wound margins and may infest old uninjured trees that have rough bark. Cytospora spp. cankers are particularly favorable for invasion (Swift 1986). Numbers of larvae may increase rapidly in a wound and many may feed in a small area. First-brood larvae develop in 40 to 50 days; second-brood larvae overwinter and complete development in about 240 days (Bobb 1959). Larvae overwinter in instars 2 through 6 (Dupree 1972). When development is completed, larvae construct cocoons and pupate in 3 to 7 days. Depending on the time of year, pupation requires 15 to 28 days. Two generations develop each year in the South (Bobb 1959); one (and sometimes a partial second) generation occurs in the North (King 1914).

Injury and Damage

Attacks are indicated by accumulation of reddish frass, usually near wounds such as split limbs and crotches, pruning scars, abrasions caused by machines, and winter injuries to bark (Bobb 1959). Cankers produced by the peach canker fungus are also infested. Larvae prefer to feed on living tissue at the edge of such injuries. Over several years, feeding can girdle the trunk or limb. Larvae concentrate on trunks 30 to 60 cm above ground and rarely occur at heights above 2.5 m (Rings 1960). A few larvae may be found below ground in association with the peachtree borer (Bobb 1959). After becoming established in a wound, larvae feed on cambium and inner bark but do not bore into the wood. Larvae are often very active and, in large numbers, can kill a tree or branch. Because this borer is not cannibalistic, many survive in even small wounds, increasing the possibility of severe injury to the tree (Bobb 1959). Pupal skins commonly protrude from the bark at infested areas. Before the 1950's and 1960's, this moth was not considered a problem in healthy, well-kept plantings (Bobb 1969). It was found mainly in larger limbs where injuries provided favorable sites for attack. However, in the past 20 to 30 years, it has gained greatly in importance by attacking trunks from ground level to branch crotches. In Virginia, it kills more peach trees than the peachtree borer (Bobb 1969). In Georgia, up to 97% of the trees in some older orchards are infested (Dupree 1972). Economic losses occur when trees die, lose scaffold branches, or are weakened by the borers (Rings 1960). It seriously damages young trees in black cherry seed orchards in Tennessee and North Carolina necessitating chemical control in some areas.

Control

Cultural practices that minimize mechanical injuries from cultivation, mowing, and harvesting reduced incidence. Diseases such as peach canker and black knot, which result in rough, healed areas, create infestation sites; the diseases should be controlled. Insect injury can be minimized by properly pruning and shaping trees when limbs are small and heal quickly (Rings 1960). Three hymenopterous paraites--Coccygomimus annulipes (Brulle), Macrocentrus marginator (Nees) (Marsh 1979), and Venturia nigricoxalis (Cushman) (Carlson 1979)--have been reported. It can be effectively controlled by applying insecticides periodically during the season to trunks and lower limbs (Bobb 1969, Rings 1960). Disruption of mating communication with sex pheromone appears feasible.

References

Solomon, J.D. 1995. Guide to insect borers of North American broadleaf trees and shrubs. Argic. Handbk. 706. Washington, DC: U.S. Department of Agriculture, Forest Service. 735 p.