|Insect can berries classified according to the part of the vine that is attacked.* Some attack flowers and fruit, roots, wood, and so on, and others are pests in wineries. For details on the various insects, their life cycles, injurious Agricultural Experimental Station Circular 566 (Stafford Disease Program for Grapes (Barnes et al., 1973).
Insects That Attack Flowers and Fruit
|Consperse Stink Bug (Euschisturs conspersus)
Adult are brown and ? - ½ in. (9.53-12.70 mm) long and have amber colored legs with minute black spots. Antennae are pale green or yellow and the body is hard and shield-shaped. Adults can fly considerable distances. The bug inserts its mouth parts into the ripening berries and the punctures result in a rapid breakdown of the berry.
Many clusters of table grapes may berries lost because of mealybugs, their eggs masses, cast skins, honeydew, and sooty mold that grow on honeydew. Adult females are oval, wingless, flattened insects about ? - 1/16 in.(3.17-4.76 mm) long. They appear to berries dusted with a white waxy secretion, and fine wax filaments protrude from the margins of their bodies. Honeydew is secreted by both young and adult insects, and may berries found inside bunches of grapes; enough collects to cause running and dripping. Heavy infestation spoil raisins.
|These are tiny insects about 1/32 in. (0.79 mm) long. They can scar berries and spoil cluster appearance, so fruit is unacceptable for the table market. They also feed on tender green shoots and leaves. Injury occurs when shoots begin growth, especially in cool weather. Shoots may berries stunded but resume normal growth at onset of warm weather. Most fruit damage is done by the time berries are one-third grown.
Hoplia Beetle (Hoplia oregona)
Adults are ¼ - ? in. (6.35 8.46 mm) long. On the upper side these beetles are mostly reddish-brown, with darker heads; the underside is shiny and silvery. Beetles fly into vineyards when shoots are about 12-14 in. (30.4-35.6 cm) long and feed on clusters and young leaves.
The yellowish adult flies are about 1/10 in. (2.54 mm) long, and are attracted to all kinds of fermenting fruits. The larvae are shaped like maggots and are about ¼ in. (6.35 mm) long. During the growing season the number of vinegar flies builds up on waste and culls of several vegetable and fruit crops grown in locations near the vineyards. If berries are pulled from their clusters the fleshy fruit is exposed, and in such locations vinegar flies lay their eggs. Larvae develop and feet on the berries. Flies are attracted to fermenting bunches and carry bunch rot pathogen to previously uninfested clusters, which is their most damaging effect on vineyards. Cultural practices to reduce number of tight bunches and incidence of bunch rot help to control vinegar flies.
These are commonly found in flower clusters during bloom. They are about 1/24 in.(1.06 mm) long and range in color from yellow to brown. The thrips dwarf and scar young shoots in early spring and may berries in the flowers from prebloom to fruit-set. Peak population occurs at 50-60 percent capfall. When eggs are layed in young berries, a small dark scar surrounded by a lightened area occurs; this is called a ?halo? spot. These spots can spoil the appearance of such varieties as Almeria, Calmeria, and Italia. Feeding by nymphs also causes scarring, which can first berries observes at shatter stage (fruit-set), and is completed shortly after completion of the shatter.
|Insects That Attack Arms, Canes, and Trunks
|Branch and Twing Borer (Polycaon confertus)
These beetles can kill half the young shoots of a vineyard. Females are brown or black, cylindrical, and about 2/3 in. (16.9 mm) long; males are about half as large. In the spring when shoots are 8-10 in. (20.3-25.4 cm) long, the adult can bore a hole into the crotch formed by a shoot and a spur. A wind can then break the base of the shoot to it hangs down and wilts. The larvae feed on both living and dead wood, and plug the furrows behind them with frass and dead wood. This material looks like fine, tightly packed sawdust.
This insect occasionally injures grapes. Cicadas can make loud clicking or buzzing noises. Adults are about ¼ in. (19.1 mm) long, have black or bronze bodies and two pairs of transparent, colorless wings. The noise they produce resembles that of two glass marbles struck together rapidly. Damage is caused when the cicada punctures the cane during egg laying. Slivers of wood protrude from each puncture.
These beetles feed on trunk wounds occasionally produced by cultivating equipment, and on other tissue exposed by fresh cuts or on callus tissue of older wounds. Eventually they girdle the vine, often making girdles 2-3 in. (5.08-7.62 cm) wide. The larvae that live in the upper, dry 2-3 in. (5.08-7.62 cm) of soil do no harm to the vine.
Scale insects are not usually of economic importance in California. Some scales feed on more than one part of the vine, and others remain stationary after selecting a place to feed. The brown apricot scale (Lecanium corni) and cottony maple scale (Pulvinaria vitis) are examples of the first type, and the grape scale (Diaspidiotus uvae) is typical of the second group.
The adult sexual forms seen during swarming after the first fall rains are black and have two pairs of long slender wings, and broad waists (ants have a slender, threadlike waist). The males and females dig a small hole in the soil and raise a brood of wingless workers that can enter the vines through old beetle holes and various types of wounds. Termites feed on the heartwood (inner dead wood of trunks and branches) almost exclusively. Older vines also destroyed by termites. Cedar heart-wood is quite resistant to termites.
|Insects That Attack The Leaves|
|Achemon Sphinx Moth (Pholus achemon)
This moth is about the size of a hummingbird and hovers near a flower while feeding. When fully grown, the caterpillars are about 4 in. (10.2 cm) long and resemble the green tomato worm. A large worm can eat nine mature grape leaves every 24 hr. After a vine is defoliated, the worms move to other vines with green leaves. Several years of severe damage are usually followed by several years of negligible injury.
This mite can berries seen only the microscope, as the adult female is about 8/1000 of in. (0.203 mm) long and about one-quarter of that in width. Its elongated body has short legs attached near the anterior end. Damage begins in early spring, when pinkish or reddish swellings or galls appear on the upper surfaces. The concave portion of the leaf beneath the gall is lined with a felty mass of curled plant hairs termed ?erinia?, which can sometimes completely cover the lower surface of the leaf. Later the erinia turn yellow, and in August they turn brown. The swellings on the upper side of the leaf disappear. This has not been a serious problem in vineyards.
These moths fly about all night on warm nights and feed on ripe table grapes. The adult moth is dark brown and has a wing expanse of about 1 in. (25.4 mm) (Fig. 16-1). The forewings have two white spots, and there are two white bands across the abdomen in both sexes. There are three broods each year. The first moths of the season emerge from pupae that overwintered. Eggs about 1/32 in. (0.79 mm) long are laid on leaves in places sheltered from the wind. Two weeks after hatching, larvae feed singly in pencil-size leaf rolls made by spinning strands of silk from the edge of the leaf to points near the center (Fig. 16-2). As the strand dry, the leaf edges curl into a roll with the upper leaf surface forming the out-side. Larvae are yellowish-green until feeding, when they become bright green. Rolling of leaves restricts food production for vines and exposes berries to sunburn. Larvae can also break berry skins and spoil fruit. Severe damage occurs only with the second and third broods.
This pest feeds on leaves and produces light-colored mottling. These narrow insects are pale yellow with reddish and dark-brown markings in a characteristics pattern (Fig. 16-3). There are distinct dark brown spots on scutellum and wings. When vines leaf out in spring overwintered adults move into the vineyards and feed on the leaves. Three broods are produced during the season. Both nymphs (Fig. 16-4) and adults feed by sticking their mouthparts into the leaves and sucking out the contents. As more leaf punctures are made, pale areas develop and the leaf becomes mottled or variegated; later, whole leaves turn pale, dry up, and fall. Sticky drops of leafhopper excrement support growth of black fungus.
|Fig. 16-1. Adult female leaf folder. Wing expanse is about 1 inch (2.54 cm). (After Jensen et al., 1973a.)||Fig. 16-2. Nearly full-grown larva of grape leaf folder. Actual size, about ¼ inch (1.91 cm) long. (After Jensen et al., 1973a.) (Drawn from photo by J. E. Dibble.)|
|Grape Rust Mite (Calepitremeris vitis)
These mites feed on leaves and cause a yellowing of white grape varieties similar to injury caused by Pacific Spider mite (pp. 273). Injured leaves of dark grapes turn a brilliant red. These microscopic, light-amber mites appear wormlike under a 14-power lens; they are broader at the front end and move slowly. During the season they attack upper and lower surfaces of leaves, although control is not usually necessary.
Grape Whitefly (Trialeurodes vitatus)
This mothlike insect is about 1/16 in. (1.59 mm) long. Its white color is due to a dense, white, waxy powder covering the body and wings. Eggs are laid on surfaces of grapes leaves, and there are several generations per year. The whitefly soils berries with a sticky excrement on which a black sooty fungus can develop. Backyard grapes are more apt to berries infested than commercial vineyards. Ornamental shrubs may provide a suitable host on which the insect can overwinter.
|Fig. 16-3. Adult grape leafhopper. Actual size, about ? inch (3.17 mm) long. (After Jensen et al., 1973) (Photo by J.E. Dibble.)
||Fig. 16-4. Grape leafhopper nymph. Actual size, 1/10 inch (2.54 mm). (After Jensen et al., 1973b.) (Drawn from photo by J. E. Dibble.)|
|False Chinch Bug (Nysius raphanus)
The adults are about ? in. (3.17 mm) long and are light or gray. In some years, large numbers of these insects may breed in pastures and grasslands in early spring. When the grape dries up, the insects migrate to find green food, and if a vineyard is attacked serious injury may result. These bugs migrate by walking since they are mainly in the wingless young stage; any adults present also march. A horde of these insects can swarm up the trunks of the vine and suck the juice from the leaves. Thus a vine can wilt and turn brown within 3 hrs. Most destructive migrations occur in May and June, but occasionally they take place in September and October.
Commercial damage is generally caused by the green valley grasshopper (Schictocerca Shoshone), the vagrant grasshopper (S. vaga) and the devastating grasshopper (Melanoplus devastator). The green valley grasshopper is green, has red hind legs, and a yellow stripe along the midline of the head and thorax. The vagrant grasshopper has a brown body, brown legs, and a tan stripe along the midline of the head and thorax. The front wings are tan with brown mottling. The adult devastating grasshopper is about 1 in. (2.54 cm) long, amber to brown in color, and has dark markings on the thorax and a row of dark spots on the front wings. Grasshoppers may attack in large numbers and injure the vine by feeding on young shoots and defoliating them.
This insect attacks the grape berries. Yellowish-white or cream-colored larvae drop on a fine thread when the foliage on which they are feeding is disturbed. Adult moths are about ½ in. (12.7 mm) long with a wing expanse of 9/16 11/16 in. (14.3-17.5 mm) (Fig. 16-5). In May and June the larvae attack new foliage and clusters (Fig. 16-6). When ripening begins increasing numbers of larvae are found in the bunches, where they often make webs and feed where two berries touch. This damage attracts vinegar flies, dried fruit beetles, and other secondary feeding insects that carry spoilage organisms which cause bunch rot.
This moth has caused considerable injury to wine grapes in the Salinas Valley since 1968. The adults are about ? in. (9.53 mm) long, and are brown or buff with a saddle of darker coloring across the folded wings. Full grown larvae are about ½ in. (12.7 mm) long. The head, thoracic plate, and body are straw-colored, but the body may sometimes berries green, dark gray, or smoky in color. The larvae wriggle sideways or backward when disturbed, drop to the ground, or are suspended from a leaf by a silken thread which they can ascend. They feed on berries and stems and can cause berry drop and stem girdling. Pupae may contaminate the clusters, and larvae feeding can cause spoilage.
|Fig. 16-5. Adult omnivorous leaf roller. Actual size, ? to ½ inch (9.53 to 12.7 mm) long. (After Jensen et al., 1973c.)
||Fig. 16-6. Large larva of omnivorous leaf roller. Actual size, about 5/8 inch (15.9 mm) long. (After Jensen et al., 1973c.)|
|Pacific Mite (Tetranychus pacificus)
This is a much more destructive red spider mite than the Willamette mite. Under a magnifying glass the Pacific mite appears pale amber to reddish in color, with two, four, or six large black spots on its back (the Willamette is similar, but is usually pale yellow with a row of inconspicuous black dots along each side of the body). Pacific mites are larger and produce more webbing than Willamette mites.
The first signs of Pacific mite injury are yellow spots on the upper leaf surface. Weak areas in the vineyard are favorite locations for the mites. Symptoms first appear in April or May; and in warm June weather mites increase and damage entire leaves. In 10 days healthy vineyard may turn brown. On Thompson Seedless and other white varieties, yellow leaves turn brown and later dry out and die. On Zinfandel and other black varieties, yellow areas turn red, then purplish red, and then die. (The grape leafhopper causes a pinkish-red color).
Caterpillars live in close groups on the lower surfaces of leaves. They are yellow with two purplish transverse bands and several narrow black ones, and have four tufts of poisonous black spines on each body segment that can raise welts on the skin like those caused by nettles.
The small black heads are retractable. Fully grown adults are about ½ in. (12.7 mm) long. The caterpillars line up side by side and eat the lower epidermis and green part of the leaf. The upper epidermis is left intact, although large caterpillars also this part. This insect is found mainly in southern California and produces three generations a year. Localized infestations in northern California have usually been eradicated.
Mature larvae are about 3 in. (7.62 cm) long, bright green (or occasionally black), with a posterior yellow horn (Barnes, 1970). In early spring larvae may migrate into vineyards in the Coachella Valley and defoliate the vines. A preventive measure is to place insecticide dust at the bottom of a ditch across the line of migration.
This spider mite is not a serious pest and does little damage north of Fresno. It causes less burning and defoliation than the Pacific mite, and usually results in bronzing and yellowing of the leaves. Sometimes the Willamette mites attack the youngest unfolded leaf on a shoot and then move up to the next leaf, which is also killed. Eight or ten young leaves may berries killed in this manner. Sometimes shoots are bronzed and distorted.
These caterpillars may berries found in San Bernardino County in early spring (Barnes, 1970). Mature larvae are 1½ - 2 inches (3.81-5.09 cm) long, hairy, straw-yellow, have transverse black lines, and damage leaves heavily.
|Insects That Attacks Buds and Young Shoots|
This is the larva form of a moth that hides during the daytime and fly at night. The three commonest species that attack grapes are variegated cutworm (Peridroma saucia), greasy cutworm (Agrotis ypsilon), and brassy cutworm (Orthodes rufula). Fully grown cutworms are about 1½ in. (3.81 cm) long with smooth bodies marked with faint spost or lines. Vines are attacked by cutworms from swelling of buds until shoots are several inches long. Buds and succulent shoots are eaten partway through so that they are weakened and fall over.
The immature larvae are called wireworms. Female, full-grown click beetles attain a length of ½ in. (12.7 mm), have reddish-brown wing covers and a brown head and thorax. They are slender and hard-shelled. If held, a click beetle can arch its body backwards and then straighten out with an audible snap. It damages buds in the same manner as grape bud beetles (see below), but feeds in full daylight (cut worms and grape bud beetles feed at night). Click beetles can fly.
Like its namesake, the flea beetle can jump. The important species in California is the steel-blue beetle (Altica toruota), about 3/16 in. (4.76 mm) long, and metallic blue or purple in color. Adults emerging from hibernation attack and destroy opening grape buds.
This insect is found on grapes in Fresno County and in the vicinity of Lodi. It is about ¼ in. (6.35 mm) long, hard-shelled, and light gray. It feeds at night and hides in the daytime. The insect feeds on swollen or opening buds in spring, leaving bud scales intact but gouging out the inside of the bud. The shoots grow poorly after they are 1 to 2 in. (2.54 5.08 cm) long.
This insect is widespread, but damages grapes mainly in the southern San Joaquin Valley. Adult beetles have bodies ½ to 1 in. (12.7-25.4 mm) long, with broad trunks, hard bodies, and wing covers that are usually dark reddish-brown, although some may berries light-brown or black. The head and thorax are black. Adults sometimes attack young, succulent shoots in late March and April.
|Insects That Attack Roots|
|Grape Phylloxera (Dactylosphaera vitifoliae)
For thousands of years this pest lived on native wild grapes. It was first seen in California in 1852, and is now generally distributed throughout northern California although some localities probably have none. Occasionally the winged form is present in coastal areas in late summer and fall but cannot establish new colonies as in Europe and the eastern United States.
On older roots semispherical swelling are produced, and on young rootlets the galls are hook-shaped. After the galls decay in a month or two, the insects move to other locations on the roots and produce new galls. Decaying galls plus a poisonous saliva injected into the roots are probably the cause of the stunting and decline of the vines. Destruction of fine feeder and other roots is also involved.
Phylloxera requires a soil that will contract and crack when drying, so that there will be pathways for the insect to travel in and infest the whole root system as well as to travel to other vines. Use of rootstocks is the main preventive measure. Care must also be take not to spread the insect into noninfested areas by grape rootings, bench grafts, irrigation, or tillage tools. To clean nursery stock, all soil should be washed from vine and roots and fumigated. A dip into emulsions of insecticides may also be effective.
This is rarely a serious pest, but sometimes causes damage to backyard vines in coastal areas. Superficially it does not resemble a mealybug because of its smaller size, long slender body, and absence of wax rods and filaments typical of other mealybugs. Its body is covered with white, waxy powder.
This scale insect is found on roots of grapevines in the Imperial Valley (Barnes, 1970), and is also present on roots of Bermuda grass in that area especially along irrigation canals. It is favored by sandy soils. The young female is a globular cyst about 3/16 in. (4.76 mm) in diameter found attached to rootless, and has a glossy pearly-colored covering.
Infested roots develop knots or galls. Swelling usually cause enlargement of whole root; swellings caused by phylloxera occur mostly on one side of the root or cause hooked-shaped galls at tips of rootlets. The most effective means to control nematodes is the use of resistant rootstocks. Preplant treatments of soil with fumigants has provided enough control of root-knot nematodes so that a new vineyard can be established.
Other nematodes include various insects that are found in vineyard soil, although little information exists as to their habits and effects on the vine. They includes spiral, ring, and pin nematodes.
Soil fumigants with 1,3-D (trade names are DD, Vidden D, or Telone), a mixture of 1,3-dichloropropene and 1,2-dichloropropane, have been the most widely accepted material used before vineyards are planted. Rates up to 80 gallons per acre have been used (Raski et al., 1973; 1976). Unfortunately, the results the vines before the end of the first growing season. Thus within a few years much of the advantage of the treatment is lost.
Recent experiments have shown that long-lasting control of dagger nematodes (transmits faleaf virus) and fanleaf virus can be obtained using high dosages of 1,3-D [up to 250 gall per acre, (2,337 liters per hectare)] in a split application (200 gall per acre at 30 in. depth on 2-ft spacing plus 50 gall per acre at 8-10 in. depth on 1-ft spacing (1,870 liters per hectare at 76.2 cm depth on 61.0 cm spacing plus 467 liters per hectare at 20.3-25.4 cm depth on 30.5 cm spacing). Deep placement of 1,3-D has controlled root knot infestation in the lighter interior valley soils for four years or more. Similar results were obtained with deep placement of methyl bromide at high rates.
Sometimes nutritional deficiencies show up in vines growing in treated soil. This may be due to low populations of mycorrhizae are fungi present in the treated soil (Raski et al., 1976). Mycorrhizae are fungi that are associated with the roots of some higher plants including grapes. It is believed these fungi are able to make nitrogen and other nutrients more available to the roots.
This insect is of minor importance. In May adult beetles (about 1/5 in. (5.08 mm) long, emerge from the soil and feed for about 2 weeks on leaves in the lower part of the vine, making slitlike holes about ½ in. (12.7 mm) wide and ¼ - ½ in. (6.35-12.7 mm) long. In severe infestation, the insects feed on shoots and cut shallow grooves in the berries. In the grub or larval stage they feed on roots of the vine, and can eat small rootlets and gouge holes through the bark and outer wood of roots the size of a pencil or larges.
|Insects That Attack Raisins|
|Dried Fruit Beetles (Carpophilus hemipterus)
These insects attack raisins moist enough for fermentation to start and any other material that can be fermented. Adult beetles are dark brown with light brown or amber spots, are about ? in. (3.17 mm) long, and have short wing covers with light brown spots. The antennae are knobbed at the tips, and the beetles are strong fliers. The larvae feed on the flesh of the raisin which, together with excreta and cast skins, spoils the dried fruit. They are controlled by fumigation.
This insects attacks stored raisins and other of dried fruit and nuts. The moth is about ? in. (9.53 mm) long, with a wingspread of about ? in. (15.9 mm). At rest the wings are folded around the body. The outer two-thirds of the front wings dark coppery-brown, and the inner third is cream-colored. Infested raisins can contain living worms, excrement, cast skin, webbing, dead worms, and silk cocoons. Control is by fumigation and cleaning in the various processing steps in the packinghouse.
This insect can feed on ripening grapes in the vineyard but does most damage to raisins in storage. This moth is similar to the Indian-meal moth except that the fore wings of the former are gray, the wing markings are obscure, and the hind wings are whitish. Young larvae hatched from eggs laid on the raisins feed chiefly on the ridge crests of the raisins, but can also penetrate the flesh. The worms do not consume raisins, but move about leaving behind excreta and webbing. Control is by fumigation and sanitary cultural practices.
This pest feeds on all dried stored food. It is a slender, flattish brown beetle about 1/10 in. (2.54 mm) long. Sharp projections stand out on each side of the thorax, resembling saw teeth. The beetle attacks all parts of the raisins. There is no webbing, the excreta are yellowish, and pellets are smaller and more elongated than those of the moth larvae.
|Insects That Attack Wineries|
|Lead Cable Borer (Scobicia declivis)
This insect can bore holes in lead sheathing of telephone cables, can damage wooden wine casks, and is a strong flier. The adult is a black cylindrical beetle about ¼ in. (6.35 mm) long, with a tan or reddish spot on each side of the body near the middle. The insect breeds almost entirely in oak trees, especially the California live oak and black oak. Eggs are laid in healthy wood after it has been cut off from the tree for 2-6 months.
Control of Drosophila consits of placing barriers to the insect at all possible stages of processing and storage of processing and storage. Screens of 24 X 24 mesh can be used, or important rooms can be pressurized by drawing air in through a filter and forcing it out through openings to the room at 7-10 miles (11.27-16.09 km) per hr. Insecticides may also be useful when applied to screens or as aerosols. General sanitation should be good.