Hickory borer
Goes pulcher (Haldeman)
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. Hickory, pecan. Commonly attacks water, mockernut,
and bitternut hickories (Beal and others 1952, Solomon 1974). Other
hickories are probably susceptible, and evidence of attack on black walnut has
been observed. Occasionally infests grafted pecan. Oak species have
been reported as hosts (Dillon and Dillon 1941), but this seems questionable.
Range. Occurs from southern Canada through the central and
eastern United States (Solomon 1974). Common in the South, but populations
vary greatly among localities.
Description
Adult. Robust longhorn beetle, ranging from 17 to 25 mm long and
5 to 8 mm wide with long antennae. Prominent spine midway along each side
of pronotum. Body pale brown to grayish yellow ground color; elytra banded
with darker brown across base and just beyond middle (Knull 1946, Dillon and
Dillon 1941).
Egg. Yellowish white, parchment-like, elongate, averages 4 mm
long and 1 mm in diameter.
Larva. Mature larva slightly robust, fleshy, generally
cylindrical, legless, and 18 to 28 mm long. White to yellowish except for
prominent dark brown mandibles and amber spiracles.
Pupa. White to greenish initially but becomes yellowish at
maturity, with eyes, mandibles, and appendages darkening considerably before
adult emergence (Solomon 1974).
Biology. Adults emerge in west-central Mississippi from early
May to early June (Solomon 1974); in Ohio, adults have been observed on foliage
in June and July (Knull 1946). After they feed on tender twigs, leaf
petioles, and leaf midribs, adults begin mating and egg laying. To
oviposit, females chew oval niches in the bark, then force the ovipositor
through the opening, downward between the bark and sapwod to deposit 1 egg per
niche. Females are known to deposit up to 14 eggs each, but probably
deposit many more. Eggs are usually deposited singly, but clusters of two
or three niches may be found. Adults live 11 to 32 days. Newly
hatched larvae produce small irregularly shaped mines of 1 to 2 cm in diameter
under the bark before tunneling into the sapwood. This behavior differs
from that of the closely related species Goes tigrinus and G.
pulverulentus, whose larvae bore directly into the sapwood after eclosion.
During late fall and early spring of the final year of development, mature
larvae construct pupal chambers by closing the uppermost portion of galleries
with plugs of long excelsior-like fibers. Pupation lasts 15 days during
mid-April to early May. The new adults chew circular emergence holes
through the bark. The life cycle is completed in 3 to 5 years.
Injury and Damage. Earliest indications of attack are egg niches
4 to 8 mm in diameter made by egg-laying females (Solomon 1974). Egg
niches are most common on the sunny aspect of the trunk; they frequently occur
in branch crotches (Craighead 1923). As young larvae begin to reach the
outer sapwood, oozing sap from the point of attack darkens the bark. In
succeeding years, the stain becomes slightly bleached or yellowish brown.
Frass extrudes from the entrance hole and falls to the ground. As larvae
reach maturity, the frass changes to excelsior-like wood fibers 8 to 12 mm
long. Larval galleries extend horizontally or obliquely upward 2 to 5 cm
from the point of entry into the wood, rise vertically another 6 to 12 cm, then
turn horizontally back to the surface. Active galleries often are
partially filled with frass, particularly along the innermost wall. Small
diverticula tightly packed with frass sometimes occur at the junction of the
horizontal and vertical tunnels of the gallery. Completed galleries are 9
to 16 cm long and 1.0 to 1.3 cm in diameter. Each borer leaves two holes,
an elongate entrance hole and a 7-mm-diameter round exit hole. As these
wounds heal, bark scars at entrance sites appear as slightly sunken slits, with
a small bulge around the periphery. The exit holes heal to form circular
scars resembling overgrown branch stubs and are visible for several years.
Borer attacks are most common on main stems 7 to 11 cm in diameter. Trunk
diameters at point of attack average less for pecan and water hickory than for
mockernut and bitternut hickories. Tree trunks are most commonly attacked
between 1.5 and 2.3 m above groundline, but occasionally attacks may occur from
the tree base to heights of 4.8 m. Attacks on large trees are restricted
usually to the upper trunk and branches. On trees of poor vigor, whose
borer injuries are slow to heal, galleries serve as nesting sites for ants and
also permit stain and decay fungi to be established. Trunks weakened by
borer galleries and woodpeckers excavations may be broken by wind. Borer
holes, stain, and decay degrade the wood for handlestock, furniture, and other
commercial uses (Solomon 1974).
Control. Heavy sap-ooze at oviposition sites kills many eggs and
early instar larvae (Solomon 1974). Woodpeckers are major predators of
borers that survive beyond the first year; up to a third of the larvae have been
destroyed by woodpeckers in some localities. No parasites have been
reported. In forest stands and woodlots, the removal of brood trees during
stand improvement operations is silviculturally plausible. In shade trees
and other valuable trees, this pest can be controlled mechanically with knife
and wire of by injecting commercial fumigants into galleries. Attacks can
be prevented with trunk sprays of an insecticide during the oviposition period.
Adult(s). James Solomon,
USDA Forest Service. |
Damage. James Solomon,
USDA Forest Service. |
Larva(e) in gallery. James
Solomon, USDA Forest Service. |
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