Note: see
bottom of page for figure descriptions.
Insect
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Injury
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Control
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Giant
bark aphid,
Longistigma caryae;
(figure 43) with relation
to other aphids, this species is very large, .25 inch (6 mm) long,
long slender legs, and is covered with a bluish-white "bloom";
several generations per year.
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Terminals,
twigs, and branches of red and white oaks; aphids feed by sucking
the plant sap; heavily infested stems are badly weakened or killed;
honeydew and sooty molds mar beauty of ornamentals.
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1
11
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Pit
scales,
Asterolecanium spp.; adult females are circular and enclosed
in yellowish, waxy, translucent covering, .04 to .08 inch (1 to
2 mm) in diameter; one generation per year.
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Found on twigs,
branches, and trunks of red and white oaks; prefers white oaks;
maturing females produce ring-like swellings or pits on the bark
(figure 44) causing a
rough appearance; branches and trees may be killed.
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11
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Kermes
scales,
Kermes spp.; adult females are globular or gall-like, yellow-brown
to black, solid or mottled, about .1 to .3 inch (3 to 7 mm) in
diameter.
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Scales (figure
45) occur on twigs, branches, near buds, near wounds, on leaf
midribs, and petioles of red and white oaks; dieback or "flagging"
of newly formed terminals, branch ends, and new leaves; early
leaf drop; mar beauty of shade trees.
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11
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Obscure
scale,
Melanaspis obscura;
adult female cover (figure
46) circular, grayish to black - resembling bark in color
.08 to 0.1inch (2 to 3 mm) in diameter; two generations per year.
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Trunks and
branches of red and white oaks; infestations are often heavy and
layered, killing branches, or resulting in general weakening,
and sometimes death of tree.
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11
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Spider
mites,
Oligonychus
spp. and Eotetranychus spp.;
.02 inch (0.5 mm) long, spider- like, eight legs, sucking mouthparts;
large numbers often present; many generations per year.
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Foliage and
buds of red and white oaks; scattered chlorotic stippling on leaves
(figure 47) later yellowing
or bronzing, then browning and dying of foliage; mats of webbing
often present; weakens tree and mars beauty.
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11
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White
grubs,
Phyllophaga
spp.; larva (figure 48)
is milky white, C-shaped, about 1 inch (25 mm) long, brown head;
adult beetle is robust, oval, brown, about .5 to 1inch (12 to
25 mm) long.
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Wide host
range, including oak seedlings and young trees; larval feeding
prunes and girdles roots; nurseries and young plantations often
damaged; adults may defoliate trees.
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11
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Figures 43 - 48.
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(43) Nymphs and
adults of giant bark aphid
(44) Pit scale on oak branch
(45) Kermes scale on oak twigs
(46) Obscure scale on oak branch
(47) Left, healthy leaves; right, chlorotic stipling caused by spider
mites
(48) Left, white grubs and root injury; right, healthy roots
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