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| Figure 30. Tree cricket damage to a blueberry stem. A portion of the surface cut away to expose holes for individual eggs. |
Snowy Tree Cricket, Oecanthus fultoni Walker
The pithy stems of raspberries and blackberries are favored locations in which tree crickets deposit their eggs, although numerous other cultivated and wild plants may serve this purpose.
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| Figure 30. Tree cricket damage to a blueberry stem. A portion of the surface cut away to expose holes for individual eggs. |
Injury
The injury is largely mechanical due to the punctures (Figure 30) made by
the female in laying her eggs. These rows of punctures weaken the canes, which,
when carrying a load of fruit, often split or break off at the puncture. Disease
fungi may gain entrance through these punctures and cause other disorders of
varying magnitude.
Life History and Habits
The winter is passed as eggs in the punctured canes; eggs hatch in June.
The young, long-legged, fragile crickets feed during the summer, partly on foliage
and partly on aphids and other small insects. They become full-grown tree crickets
during August, and from then on until autumn, the females are busy making rows
of punctures in the canes and placing their eggs within.
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| Figure 29. Adults of the snowy tree cricket (female on left, male on right). |
Description
The adult tree crickets are rather fragile, sluggish, greenish-white creatures
(Figure 29). They frequent the field during the fall, are active mostly at night,
and are rarely observed during the day. In the male cricket, the transparent
wings are flattened across the back. In the female, the wings are folded around
the body.
Cultural Control
Eliminating wild brambles from the vicinity of cultivated raspberries is
valuable in preventing injurious populations of tree crickets. Pruning out old
fruiting canes after harvest, particularly those with egg punctures, and the
removal and destruction (by burning) of egg-infested canes in the spring are
recommended practices.
Rose Scale, Aulacaspis rosae (Bouché)
The rose scale is one of a group of scale insects known as the armored scales. They attack the stems of roses, blackberries, raspberries, and dewberries growing in damp, shady places. The rose scale is almost cosmopolitan in nature, occurring whenever brambles and roses are grown, and is widely distributed over the United States and Canada. It is not usually a serious pest in commercial berry plantings due to growers' ability to easily control it. This scale is most abundant in humid areas where the amount of sunlight is reduced.
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| Figure 31. When allowed to multiply, rose scale can turn cranes white. |
Life History
The rose scale may hibernate in all stages from the egg
to pregnant females, mostly, however, as young scales of both sexes. In Ohio,
there are at least two generations annually, beginning with egg hatch in late
May or June and a second generation in August. Eggs are laid and protected by
the scale of the mother insect until hatch, at which time they crawl from beneath
the scale of the parent and move actively about until finding a location on
the plant that seems favorable. Then they insert their threadlike mouthparts
into the epidermis of the cane and begin feeding on the sap of the plants. After
feeding a short time, they molt and lose their legs and antennae. The cast skin
is incorporated into the scale, which now forms over the body of the insect
and which is composed of thin threads of wax that were excreted from the body
wall of the scale and have run together.
The female scales molt twice during their life and remain under the scale for the duration of their life. The males, after molting twice, have a more elongated body and, after passing through the prepupal and pupal stages, assume the adult form. In the adult stage, the male is a very small, two-winged, yellowish insect with three pairs of legs, eyes, antennae, and a prominent long appendage projecting from the tip of the abdomen. The adult males actively seek out the female scales and mate with them but do not feed in this stage. After mating, adult females continue to feed and produce eggs.
Description
Female scales are round in shape, nearly 2.5 mm (1/10 inch)
in diameter. The shell, dirty white in coloration with an orange-yellow dot
in the center, covers orange or pinkish bodies and red eggs. The males are considerably
smaller, long and narrow, and snow-white in coloration.
Cultural Control
Prune out and burn all heavily infested canes that can
be spared. Elimination of wild brambles in the vicinity of cultivated plantings
may be beneficial.
Raspberry Cane Borer, Oberea bimaculata (Olivier)
Family Cerambycidae (The Long-Horned Beetles)
The raspberry cane borer is a native insect that is generally distributed over the northeastern United States and Canada. Due to similarity in common names, there is some confusion between raspberry cane borer and red-necked cane borer. However, damage and appearance of the adults are quite unique.
Symptoms
The telltale signs indicating the presence of the raspberry cane borer in
a planting are wilted shoot tips (Figure 32). This usually is observed in early
June. 12 to 20 cm (5 to 8 inches) back from the tip, two girdles, 19 mm (3/4
inch) apart (Figure 33), confirm cane-borer injury.
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| Figure 32. Typical wilting caused by girdling of the raspberry cane
borer. |
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| Figure 33. Close-up of the two girdles of raspberry cane borer. |
Description, Life Cycle, and Habits
The adults of the cane borer are slender, dark-colored beetles, about 12
mm (1/2-inch) long with antennae as long as the body. The prothorax (area behind
the head) is yellowish to bright orange with two or three black dots on the
upper surface. The beetles appear in June and may remain active until late August.
After laying an egg, the female girdles the cane about 6 mm (1/4 inch) above
and 6 mm (1/4 inch) below the egg, resulting in the tip of the shoot wilting
and dying. Upon hatching, the larvae bore downward in the cane, overwintering
not far below the point of the lower girdle. The next season, they continue
to bore until reaching the crown. The second winter is passed at or below ground
level. The following spring, full growth is attained and larvae pupate. The
new adults begin emerging in June. Two years are required to complete the life
cycle.
Cultural Control
The best cultural control practice is the destruction
of the canes that show characteristic injury. If pruning is done within a few
days after the wilted tips appear, only 25 mm (1 inch) or so below the wilted
portion of the tip needs to be removed. To be sure, inspect the cut surface
of cane; if there is evidence of borer damage below the cut, continue cutting
off short sections until all bored area has been removed. Burn all prunings
to destroy the insect inside.
Red-Necked Cane Borer, Agrilus ruficollis (F.), Family Buprestidae (Metallic Wood Borers)
This colorful metallic beetle is widely distributed in the eastern United States and Canada. Since 1980 it has become a more serious pest in Ohio and neighboring states. Common hosts are raspberries, blackberries, and dewberries.
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| Figure 35. Gall produced by larva of red-necked cane borer girdling stem. |
Seasonal History
Eggs are laid singly on the stems in May or June. Upon hatching, the young
larva bores into the sap wood and under the surface of the bark, forming a spiral
tunnel going around the cane five or six times. This girdling of the stem causes
a swollen area or gall (Figure 35), which appears in July or August. After girdling
the stem, the larva bores into the stem and lives in the pith. It bores up for
about 15 cm (6 inches) and overwinters in this burrow. In spring, it pupates
and finally emerges as an adult in May or June.
Damage
Adults feed on foliage, causing only minor leaf loss. The major damage is
done by the larvae as they girdle the canes. This in turn slows growth, favoring
the insect. The girdling weakens the canes and, as a result, fruit production
is limited from infested canes. In extreme cases, the cane may be killed outright.
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| Figure 34. The adult red-necked cane borer has short antennae. |
Description
Adult beetles are metallic bronzed blue-black in color with a coppery red
prothorax (Figure 34). They are just over 6 mm (1/4-inch) long. Adults
are often seen on sunny mornings on the foliage. They are easily disturbed and
fly away quite readily if approached. Adults are present from May to August,
feeding on foliage and ovipositing on canes. Larvae are long and narrow with
an enlarged head. Fully-grown larvae reach a length of more than 12 mm (1/2
inch).
Cultural Control
Destruction of infested canes is the simplest remedy but, to be effective,
wild host plants in the vicinity should be eliminated.