Insects Attacking Flower Clusters and Berries
Home
Multicolored Asian Lady Beetle, Harmonia axyridis
(Pallas)
The multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera:
Coccinellidae) was first introduced in California by USDA agricultur
al
research scientists as a biological control agent. This introduction was deemed
unsuccessful. However, it was reintroduced in the eastern United states in the
late 1970’s and early 1980’s to control soft-bodied insects like the pecan aphid
and pear psylla. Since its introduction it has spread throughout most of North
America.
Adult beetles are domed, round to oval in shape typical of other lady beetles.
The name “multicolored” refers to the many color forms of the adult lady
beetles. Coloration variants are shades of yellow, orange, and red; with or
without black spots on the wing covers.
This species can be recognized and distinguished from other lady beetles by the
following characteristics. On the white pronotum (the middle body segment
between the head and abdomen) there are several black markings, which tend to
fuse into a regular to irregularly shaped “M” or
“W” depending on your vantage point.
Life cycle: The life cycle from egg to adult requires about a month or
so, depending on the weather. Eggs hatch in 3 to 5 days. The larval stage
lasts up to 14 days, during which time they consume large numbers of aphids,
scale insects and other soft bodied insects. Pupation lasts 5 to 6 days
followed by adult emergence. The adults are rather long lived with some beetles
living up to 3 years. At least two generations with a partial to complete third
generation, occurs each growing season. In the fall when the host plants begin
to dry and cooler weather approaches adult beetles begin to seek overwintering
sites. They are attracted to vertical walls or cliffs where they seek shelter
in cracks and crevices. Once one lady beetle lands, many others may follow in
an aggregating behavior.
Behavior: The feeding habits of the multicolored Asian lady beetle (MALB),
are for the most part not well documented in North America. They are
primarily
arboreal and spend a great deal of their time in the upper canopy of trees.
Thus, we have little information on their feeding activities. In 2001 the
soybean aphid was quite abundant throughout the Midwest and the lady beetle
population exploded causing numerous complaints from home owners and fruit
growers.
Control: Since the MALB is not a native species, few diseases or
parasites have been associated with this beetle. Adult beetles have been
associated with vectoring fungal pathogens and therefore their aggregating
nature may be favorable to the dissemination of bunch rot and other diseases
from one grapevine to another.
Grape Berry Moth, Endopiza viteana Clemens
Description and Life Cycle: This is the major insect pest of grape
berries in the eastern United States and Canada. When vineyards are left
unmanaged up to 90 percent of the fruit often is destroyed by the larvae and the
diseases facilitated by the damage inflicted upon the fruit. Infestations vary
greatly from vineyard to vineyard, from year to year, and within a vineyard.
However, vineyards bordering wooded areas are most vulnerable.
The adult is a mottled-brown-colored moth with some bluish-gray on the inner
halves of the front wings. The larvae of this small moth are active, greenish to
purplish caterpillars about 3/8 inch long when fully grown. Grape berry moths
overwinter in cocoons within folded leaves in debris on the vi
neyard
floor and within adjacent woodlots. After emerging in the spring, the adults
mate, and females lay eggs on or near flowers or berry clusters. Newly hatched
larvae feed upon the flowers and young fruit clusters. Larvae that hatch in June
make up the first generation of grape berry moth and will mature from mid to
late-July or August. After mating, females lay eggs on developing berries, and
this second generation matures in August or September. Larvae of the second
generation, after completing their development, form cocoons in which they
overwinter. A third generation occurs commonly in the southern range of the pest
and occasionally in the northern tier of states.
Damage Symptoms: First-generation larvae web small
flower buds or berries together in early June and feed externally on them or on
tender stems.
Larvae
that attack grape bunches during this time are difficult to see.
Second generation larvae tunnel directly into the green berries and feed
internally. Conspicuous reddish
spots develop on the berries at the point of larval entry. Berries affected in
this manner are known as "stung" berries. The second generation is potentially
more damaging than the first. A single larva may destroy 2 to 6 berries in a
cluster, depending on berry size, and several larvae frequently inhabit a single
cluster.
At harvest, severely infected bunches may contain several larvae, and many of
the berries may be completely hollowed. In many cases, bunches are covered with
bunch rot fungi and infested with Drosophila spp. fruitflies, and often having
an unhealthy appearance.
Management (How to survey vineyard to determine percentage of clusters
damaged.): A protectant insecticide may be needed to prevent damage in
areas heavily infested by grape berry moth. The number of spray applications
depends on the amount of infested berries the grower is willing to accept. Table
grapes require more attention than grapes grown for juice. Corrective measures
are usually suggested if more than 5% of the clusters are injured. To determine
the percentage of clusters damaged you should randomly inspect 100 clusters
along the perimeter of the vineyard and 100 clusters toward the center of the
vineyard. This method will tell you if treatment of the entire vineyard is
necessary. Treatment of perimeter rows maybe all that is necessary to control
this pest. Control of maturing larvae in mid-to late-July is particularly
important.
Cultural controls can be used to kill the overwintering pupae in leaves. Leaves
can be gathered and destroyed in the fall, or leaves can be buried within the
soil in the spring, 2 weeks before bloom, by rototilling or cultivating.
An alternate method of control using pheromone rope ties to disrupt the males of
the grape berry moth was approved by the EPA in 1990. This method prevents
mating, thus reducing the number of fertile grape berry moth females in a
treated vineyard. This method is most effective in vineyards at least 5 acres in
size. Ties are dispensed manually at a rate of 400 ties per acre. When a
vineyard is under heavy pressure from berry moth, it may require spot treatment
with an effective insecticide at the source of the infestation. Studies indicate
that vineyards in close proximity to external berry moth sources such as
woodlots, may require an application of insecticide in addition to the ties for
control of this pest. Vineyards utilizing these ties should continue to scout
their plantings in the same manner as previously mentioned. If thresholds are
reached the decision to apply an insecticide should be considered.
Monitoring Male Moths: Pheromone traps are available to monitor the
emergence of male grape berry moths during the season. This information may be
useful for optimal spray timing; sprays should target egg hatch and young larval
activity, which occurs several weeks after the first moths are trapped. A
minimum of 3 traps for monitoring a single block of approximately 10 to 15 acres
is recommended. Traps hung from the top wire of the trellis should be placed
around the perimeter of the vineyard before bloom and should be at least 100
feet apart. Sticky trap bottoms should be checked weekly for moths, and
pheromone caps should be changed monthly to obtain accurate flight information.
Every vineyard location is unique, and growers should not rely on pheromone trap
data from other vineyards for timing insecticide sprays.
Control: Pheromone traps should be utilized in vineyards with a
history of grape berry moth problems. Trapping of adult male moths indicates the
beginning of flight activity. Mating and egg laying will occur over a 2 to 3
week period following the first detection of flight activity. A protective cover
spray may be required during this period to prevent egg laying and hatch. Early
season control of this pest may prevent it from becoming well established within
the vineyard, and may eliminate the need for control later in the season. It
should be noted that the second flight activity period occurring in late July
and August is the most important. These adult moths in late summer produce the
eggs which hatch into larvae capable of causing major damage to the maturing
fruit. One should not solely depend upon a pheromone trap for detecting this
late season threat. Scouting should be implemented on a weekly basis after
bloom. If berry cluster damage reaches 6% in grapes used for processing or 3% in
those grown for fresh market, a protective cover spray should be applied.
Rose Chafer, Macrodactylus subspinosus (Fabricius)
Description and Life Cycle: Rose chafer adults attack grapes at
bloom as they emerge from the soil. Not only due they destroy the fruit at
blossom, in addition, they frequently skeletonize the leaves, leaving only the
large veins intact. This insect is especially abundant in areas of light, sandy
soil where beetles may appear suddenly as grapes begin to bloom.
The
ungainly beetles have a straw-colored body, reddish-brown head and thorax with
black undersurface. The adult rose chafer is about 0.5 inches in length with
long, spiny, reddish-brown legs that gradually become darker near the tip. As
they age, hairs are worn off the head and thorax with normal activity revealing
the black color below. Thus, they become mottled in color as they mate and move
around in the flower clusters making it possible to distinguish newly emerged
adults from older specimens. Females frequently loose more hairs, particularly
on the thorax, in the mating process. Eggs of the rose chafer are oval, white,
shiny in appearance, and about 0.05 inches long and 0.03 inches in width. Larvae
are C-shaped white grubs about 0.8 inches long and 0.12 inches wide when fully
grown. Mature larvae have three distinct pairs of legs, a brown head capsule,
and a dark rectal sac visible through the integument. Larvae are found in sandy
soil feeding on grass roots and can be identified by a distinctive rastral
pattern. The pupae are light yellowish-brown in color and haveprominent legs.
They measure about 0.63 inches in length.
Adult
rose chafers become active in northeastern North America from late May to early
June. The adults appear suddenly. It seems as though the entire population
reaches maturity practically at the same time, and multitudes of beetles
suddenly make their appearance. Beetles feed and mate soon after emerging from
the soil. It is common to see mating pairs in the newly formed grape clusters.
Females deposit eggs singly a few centimeters below the soil surface. Mating and
egg laying occur continuously for about two weeks with each female depositing 24
to 36 eggs. The average lifespan of the adult is about three weeks.
Approximately two weeks after being deposited, eggs hatch into tiny, white,
C-shaped grubs. The larvae feed on the roots of grasses, weeds, grains, and
other plants throughout the summer, becoming fully developed by autumn. However,
it is not easy to collect the larvae of rose chafer. They have been found
occasionally on the roots of orchardgrass but never in proportion to the numbers
of adults found in adjacent grapes. Larvae move downward in the soil as soil
temperatures decline and form an earthen cell in which they overwinter. In the
spring, larvae return to the soil surface, feed for a short time, and pupate in
May. After two weeks in the pupal stage the adults emerge and crawl to the soil
surface to begin their cycle again. There is but one generation per year.
Damage Symptoms: Despite its common name, the rose chafer attacks
the flowers, buds, foliage, and fruit of numerous plants including grape, rose,
strawberry,
peach, cherry, apple, raspberry, blackberry, clover, hollyhock, corn, bean,
beet, pepper, cabbage, peony, and many more plants, trees, and shrubs. Adults
emerge about the time of grape bloom and often cause extensive damage to
foliage. Blossom buds are often completely destroyed, resulting in little or no
grape production. Feeding activity on various plants may continue for four to
six weeks. Damage can be especially heavy in sandy areas, the preferred habitat
for egg-laying. A toxin present in the beetles may kill poultry.
Management: Adult chafers begin emerging in late May and early June
at the time of grape bloom. A spray application is recommended if more than 2
beetles per vine are present. If only a few beetles are present , they may be
handpicked from the vine and destroyed. The pupal stage is extremely sensitive
to disturbance therefore, cultivating between rows may be effective in
destroying a good number of chafers, however it is our experience that growers
with sufficient numbers of beetles to inflict economic damage will not be able
to control this pest by this method of cultural control. An alternative method
to chemical control has been developed by the department of Entomology at Ohio
State University for this pest. This method utilizes a very powerful feeding
attractant and a Japanese beetle trap. Intensive trapping over a 4 year period
reduced the population to below the threshold level of two beetles per vine. An
application of insecticide may required in combination with the trapping effort
if the population is extremely high. It is our experience that it takes a couple
years of intensive trapping to reduce the population within a heavily infested
vineyard to the point that chemicals are no longer needed to control this pest.
Monitoring: Scouting for this pest within your vineyard should
begin in late May and continue through late June. Newly emerged adults may be
found feeding upon young grape buds and foliage. If numbers reach 2 beetles per
vine control methods should be utilized. Monitoring may also be conducted by
utilizing the attractant developed for rose chafer. Traps should be placed
around the perimeter and dissecting the vineyard. For monitoring purposes these
traps may be spaced every 100 ft. and should be checked daily for newly emerged
chafers. If beetles are encountered, control methods should be considered if
beetles average 2 or more per vine.
Control: When only a few beetles are present one may handpick them
from the plant and destroy them. Where populations are large and pose a threat
to the grape crop, massive trapping may be a safe alternative to applying
insecticide. Results utilizing this new powerful attractant have been very
positive. The desired effect of mass trapping, which is to bring the beetle
population to below threshold level, is usually achieved after a couple years of
trapping. Chemical control methods should be utilized when beetle pressure
exceeds an average of two beetles per vine. To determine the number of beetles
per vine one should randomly survey 25 vines at all four corners of the vineyard
and 25 in the center of the vineyard. This will give you the total number of
beetles present on 125 vines surveyed. Divide the number of vines (125) by the
number of beetles present to obtain the average number of beetles per 125 vines.
If this average is above 2 beetles per vine, then treatment is recommended. It
should be noted that, with this survey method, one can determine if the chafer
infestation is present throughout the vineyard or just located in a specific
area. If the area is localized, spot treatment of the infestation may be all
that's required. Treatment with an insecticide should be after bloom when the
first newly emerged beetles are detected in adequate numbers to pose concern. A
second application may be required if pressure is severe and rainfall is
frequent. Protection of the young grape cluster is critical and should be
maintained throughout June.
Grape Blossom Midge, Contarinia johnsoni Felt (Diptera:
Cecidomyiidae)
The grape blossom midge is a small fly that lays its eggs in unopened grape
flower buds. Small maggots, or larvae, hatch and eat the inner portions of the
flower. Buds affected in such a manner are incapable of forming a flower and
thus a berry. Infested flower buds are slightly enlarged and lower portions are
red. This is in contrast to normal flower buds, which are completely green. The
grape blossom midge has one generation per year; it passes the winter as a
full-grown larva.
This midge is most often present on vines near brushy or wooded areas, and it
rarely causes much damage.
Red-banded Leafroller, Argyrotaenia velutinana
(Walker) Lepidoptera: Tortricidae)
Larvae of the red-banded leafroller occasionally infest grape clusters. This
insect overwinters as a pupa. Moths emerge in late April and lay eggs on newly
set grape clusters. The larvae eat shallow holes into the berry; they web
several berries together and feed on them and the cluster stems. These
first-generation larvae mature in early June, pupate and emerge as moths, which
lay eggs during June. The second generation larvae emerge and complete
development about mid-August. Second generation moths emerge in late August and
lay eggs, which give rise to the third generation.
Ordinarily, the third generation of this moth species is the most conspicuous
and abundant. The larvae construct webbing within the grape.jpg)
clusters, chewing holes into the berries and feeding on the cluster stems. The
third generation may cause considerably more damage than the first two.
.jpg)
Serious infestations of the red-banded leafroller are not common. A few infested
clusters may be found every year, and the larvae may be present on other fruit
such as apples.
The larva of the red-banded leafroller is a pale green caterpillar and is 5/8
inch long when mature. The adult moth is light brown with an irregular,
reddish-brown stripe across each front wing; it is about 1/2 inch long.
Grape Seed Chalcid, Evoxysoma vitis (Saunders)
(Hymenoptera: Eurytomidae)
The grape seed cha1cid is a small, wasp-like insect that lays its eggs in grape
berries when the berries are nearly full size but still green. Larvae hatch,
enter the seeds and feed on the contents of the seeds. The fruit around the
infested berries shrivels and dries out. The grape seed chalcid overwinters
within grape seeds on the ground. Adults emerge in late May or June.
Outbreaks of this insect are rare. Grape cultivars having smaller berries appear
to be preferred over those which bear larger fruits. The grape seed chalcid
attacks generally are confined to wild grapes.
Grape Curculio, Craponius inaequalis (Say) (Coleoptera:
Curculionidae)
The grape curculio is a black snout beetle, about 1/8 inch in length, which lays
its eggs in grape berries. The developing larvae feed on the berries, consuming
the pulp and seeds. Damage by this insect is commonly confused with that of the
grape berry moth.
In the spring, adult beetles become active around the time of ‘Concord’ grape
bloom. They feed for about two weeks before laying any eggs. The beetles feed on
the upper surfaces of grape leaves; the damage appears as short, curved lines
arranged in groups. The female deposits eggs in cavities she makes under the
skin of grape berries. The white larvae are legless, which is in contrast to
grape berry moth caterpillars. In about three weeks, larvae complete their
development, drop to the ground and pupate. New adults emerge several weeks
later and feed on grape foliage until the onset of cold weather at which time
they seek a place to hibernate. There is one generation of grape curculio each
season.
Yellowjackets, Hornets and Paper Wasps (Hymenoptera: Vespidae)
Grape berries that become overripe and split open commonly are attacked by
yellowjackets, hornets and paper wasps. These insects feed on the pulp and juice
that become available when conditions leading to berry splitting are prevalent.
Because these wasps are often present in clusters at harvest time, they are a
nuisance to pickers. Economic damage to the crop by these stinging insects is
rare.
Current pesticide recommendations may be found
Here
Home