Persimmon borer
Sannina uroceriformis Walker
From: 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.
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).
Adult(s) male. James Solomon,
USDA Forest Service. |
Damage root collar and root damage. James Solomon,
USDA Forest Service. |
Larva(e) in root gallery. James Solomon,
USDA Forest Service. |
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