Persimmon Borer
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Hosts
Persimmon. Persimmon is the only known host. Native wild persimmon is preferred; introduced Japanese persimmons grafted onto the native persimmon rootstocks are sometimes attacked. Improved varieties are probably susceptible.
Range
Throughout the range of its host along the Atlantic Coast from New Jersey to Florida and westward to Texas, Oklahoma, Missouri, Kansas, Ohio, and Indiana (Engelhardt 1946)
Description
Adult
Bluish black, wasplike, clearwing moth with wingspan of 28 to 32 mm; female slightly larger than male. Typically, distinctive orange band across abdomen, though lacking in some. The blue-black color and orange abdominal band cause this species to be confused with the female of the more common peachtree borer. Opaque forewings, somewhat opaque hindwings with small transparent areas between veins at base of wings (Engelhardt 1946). Distinctive anal tuft in male with five long hair pencils on segment 8, consisting of two lateral pairs and one anal.
Larva
Young larva dull or grayish white; later becomes almost white, except for brown head and light brown sclerotized area dorsally on prothotax. Mature larva about 24 to 30 mm long (MacKay 1968).
Pupa
Light brown becoming darker with age and found in dark frass-covered cocoon 25 to 63 mm long (Herrick 1907).
Biology
Moths emerge April to early July in the Gulf Coast region and mostly in June and July in the northern range (Engelhardt 1946). Over 400 males were captured between May 12 and July 16 in Mississippi in pheromone-baited traps (Solomon and others 1982). Moths emerge in the morning and mate from late morning until noon. Females deposit eggs on the bark of the lower trunks of hosts or sometimes drop their eggs on the ground around the base of hosts. On hatching, larvae move to suitable sites, usually at or near the root collar, to bore into the bark, but attacks sometimes are initiated 30 to 60 cm above ground. Young larvae begin feeding and mine downward in the cambium. Mines occasionally meander but usually extend essentially straight down. At or slightly below the groundline, larvae extend tunnels into the wood, sometimes to the center of both the lateral and tap roots. Root galleries most commonly extend down to a depth of 20 to 25 cm (Herrick 1907), but can reach 43 to 56 cm in the taproots (Riley and Howard 1892). Larvae overwinter in their galleries below the soil line and pupate during spring. When ready to pupate larvae extend their galleries upward in the roots to groundline or just above. They chew through the bark and construct large cocoons upward and outward from the bark. These tubelike cases are made of dark frass, bits of bark, and silk; they are 25 to 62 mm long (Herrick1907). Pupation occurs in the galleries. In about 3 weeks, the pupae become active and work their way up through the tubelike cocoons to project through the covers for adult emergence. The life cycle requires 2 to 3 years (USDA FS 1985).
Injury and Damage
Damage is sometimes difficult to diagnose, as most tunneling occurs below ground. However, many attacks initiate at or slightly above the root collar, providing some evidence for diagnosis. Black gum exudate, particles of bark, and frass are often present, especially during early stage of attack on the base of the trunks. Sometimes, bark loosens at mined or burrowed sites, exposing tunnels leading down and extending below ground. Most aboveground mines on trunks are just under the bark in the cambium but extend into the wood at or near ground level. Damage can be readily identified by excavating roots. Small roots may be hollowed out, leaving only a shell, or may be severed. Large roots may have two or more galleries. Repeatedly attacked roots will be heavily scarred from previous injury. Heaviest populations occur in young trees 12 to 50 mm in diameter, but trees up to 20 cm at the root collar have been found to be moderately infested (Herrick 1907). Seedlings and young trees may have their taproots tunneled out, causing them to break off and die. Trees that appear weak and in decline should be examined for this borer. Seedlings and sprouts growing on abandoned fields, roadsides, and ditch banks seem particularly susceptible to attack. Larvae are voracious feeders that tunnel extensively and deeply into roots, weakening and sometimes girdling and killing them. Larval feeding causes seedlings and young saplings to wilt and break. Usually, larvae injure large trees less seriously (Engelhardt 1946), but populations sometimes are large enough to cause weakening.
Control
Little is known of natural enemies. Evidence of woodpecker and rodent excavations of larvae around the base of trees has been observed, but no parasites have been found. No direct controls have been developed, but measures recommended for the peachtree borer would probably be effective (Engelhardt 1946).
Gallery
 Photo by James Solomon, USDA Forest Service, Bugwood.org |  Photo by James Solomon, USDA Forest Service, Bugwood.org |
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.
