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Oak Pests - A Guide to Major Insects, Diseases, Air Pollution and Chemical Injury


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MINOR BORERS

Note: see bottom of page for figure descriptions.

Insect

Injury

Control

Little carpenterworm,
Prionoxystus macmurtrei;
larva (figure 29) pink to white, dark head and thoracic shield, 2.25 inches (57mm); adult gray-mottled moth; life cycle 2 to 3 years.

Trunks and branches of sawtimber and shade trees; prefers red oaks; mine under bark, and gallery in wood .4 x 6 inches (I x 15 cm); frass of wood chips and excrement pellets; causes lumber degrade, disfigures ornamental trees.

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Beech borer, Goes pulverulentus;
roundheaded larva, white, legless, cylindrical, about 1.5 inches (37 mm); adult brownish-gray longhorned beetle; life cycle 3 to 5 years.

Trunks of saplings and poles of red oaks; attacks are clustered (figure 30); galleries are about .4 x 8 inches (0.9 x 20 cm); grayish frass with fibrous shreds extruded in ribbons; degrade, entries for decay, stem breakage.

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Spotworm borer,
Agrilus acutipennis;
larva is slender, flattened, white, about 1.3 inches (32 mm) long; adult beetle is narrow, dark metallic blue, about .5 inches (12 mm) long; a generation requires 2 years.

Trunks over .5 inch (12 mm) in diameter in white oak group, particularly heavy on overcup oak in river bottoms; larvae tunnel spirally in outermost growth ring (figure 31); spot stains and frass-packed tunnels are defects that degrade lumber.

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Flatheaded appletree borer,
Chrysobothris femorata;
larva (figure 32) is flatheaded, white, about I inch (25 mm) long; adult beetle is oval, flattened, greenish bronze, about .6 inch (16 mm) long; one generation per year.

Trunks and branches of red and white oaks of all sizes; larvae bore into phloem and outer sapwood; galleries girdle and kill small trees; newly transplanted trees and those weakened or stressed are most susceptible.

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Oak branch borer,
Goes debilis;
roundheaded larva, legless, yellowish-white, about .6 inch (15 mm); adult longhorned beetle, mottled reddish-brown and gray; life cycle 3 to 4 years.

Small branches and terminals about .3 to 1.5 inches (9 to 37 mm) in diameter, mainly white oaks; attacks (figure 33) near crooks and branch crotches; galleries about .2 x 3 inches (6x75 mm); yellowish frass protrudes from elongate entrance hole; infested stems become swollen, and often break or die back.

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Oak-stem borer,
Aneflormorpha subpubescens;
roundheaded larva, slender, about .7 inch (18 mm) long; adult narrow, light brown, spine on the third and fourth segments of antennae. One generation per year.

Seedlings and sprouts about .5 to 1 inch (12 to 25 mm) diameter; red and white oaks; larva bores down center of stem, cutting off sections, burrows to stem base or roots to overwinter; frass is ejected through row of small holes in bark (figure 34), kills large numbers of seedlings and sprouts in Southeast.

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Figures 29 - 34. --

(29) Little carpenterworm larva
(30) Cluster of beech borer attacks on sapling by
(31) Bark removed to expose larval galleries of spotworm borer
(32) Flatheaded appletree borer larva in gallery under bark
(33) Oak branch borer entrance hole, with yellow frass
(34) Oak-stem borer larva in gallery of stem with row of small holes

 
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