Baccharis borer
Oidaaematophorus balanotes (Meyrick)
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. Baccharis, bayberry. Baccharis and bayberry groups
reported as hosts (Cashatt 1972, Forbes 1923); recent unpublished findings
suggest that eastern baccharis is a major host.
Range. Primarily a southeastern species, found from southern
Florida north to Maryland and New Jersey and west to Texas and Arizona (Barnes
and Lindsey 1921, Cashatt 1972, Forbes 1923, Kimball 1965).
Description
Adult. Largest of stemboring pterophorids, slender-bodied moth
with long legs and narrow wings (Barnes and Lindsey 1921, Cashatt 1972, Meyrick
1908). Forewings cleft and brownish white with dark spots at vein tips and
indistinct brown dash line extending from base to near cleft. Hindwings
pale brown. Wingspan varies from 30 to 42 mm. Light brown to
brownish white or tan with indistinctly striped abdomen, whitish antennae, and
pale brown legs.
Egg. Yellowish white, oval, and about 0.54 by 0.33 mm.
Larva. Creamy white with brown markings and 18 to 25 mm long
when mature. Head dark brown around the mouthparts, with light brown
mottling elsewhere. Thoracic shield with brown granulations. Anal
plate brown and hardened with two prominent prongs and ringed with long
hairs. Crotches in uniordinal semicircle.
Pupa. Slender, tannish brown, and 16 to 22 mm long.
Biology. Adults emerge every month, depending on location
(Barnes and Lindsey 1921, Cashatt 1972). In Florida, moths have been found
during all months, but mostly in late winter and spring. Emergence is
recorded during July and August in Maryland, August in Arizona, July and October
in South Carolina, and from June to November in Texas; reared entirely during
September in Mississippi. Most deposit eggs on the bark of hosts.
Larvae enter the bark and make long, narrow, nearly straight galleries in
wood. Most attacks occur in the main stem and less frequently in
branches. Entrance holes have been found from just above the groundline to
1.5 m. Larval galleries always enter bark and wood at an oblique angle,
and nearly always extend downward into the roots, sometimes as much as 10 cm
below ground. Although the galleries are in the xylem, they are usually
only a few millimeters beneath the wood surface. Completed galleries range
from 15 to 23 cm long and 4 to 5 mm in diameter. Pupation occurs freely
within the gallery for 16 to 19 days, without a pupation chamber. Empty
pupal skins at various locations in galleries indicate that moths eclose from
the pupae within galleries, unlike many other woodboring Lepidoptera in which the
pupae move to the exit holes for adult emergence. There appears to be one
generation per year, with considerable overlapping of broods in some
areas.
Injury and Damage. The earliest evidence of attack is
sap-stained spots, often mixed with fine frass on bark. Later, round to
oval entrance holes 2 to 4 mm in diameter, often with yellowish white frass
adhering to bark below entrances, become noticeable. Dissection of
infested stems reveals the long cylindrical nearly straight galleries and
sometimes tunneling larvae. Bark occasionally cracks open along shallow
galleries and forms long bark scars that show evidence of previous
infestation. Small stems, particularly branches, sometimes break at
injured sites. Heavy infestations have been found recently in thickets of
eastern baccharis near Jackson, Mississippi.
Control. Ichneumonid parasites--Telelucha sp.-- have been
reared from specimens in Mississippi, but rates of parasitism have been
low. Direct controls have not been low. Direct controls have not
been needed. This borer is being studied by Australian scientists as a
possible biocontrol agent for weed Baccharis spp. in pastures.
Damage long narrow galleries in Baccharis halimifolia L. Baccharis (groundseltree, saltbrush) is a common weed found in the Southern United States on regeneration sites. James Solomon,
USDA Forest Service. |
Damage exit hole and frass in Baccharis in South Carolina. James Solomon,
USDA Forest Service. |
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