Filbert Insect and Mite Pests

Station Bulletin 643 July 1980

Agricultural Experiment StationOregon State University, Corvallis

ContentsIntroduction 1

Harmful Insects 1

Filbertworm 1

Filbert Aphid 2Filbert Leafroller 3Obliquebanded Leafroller 6Filbert Bud Mites 6Filbert Nut Weevil 7Scale Insects 7Syneta Beetle 8Eyespotted Bud Moth 8Tree Crickets 9Ambrosia Beetle 9Apple Mealybug 9

Beneficial Insects 10Lady Beetles 10Syrphid Flies 10Green Lacewing 11Mind Bugs 12Parasites 12Predator Mites 12

AbstractThe purpose of this publication is to describe the important pests of

filberts and to review their life histories, damage, and control. Illustra-tions and simple methods for pest identification, as well as how to samplefor the pests, also are included. Specific insecticide and miticide spraysare not mentioned in this bulletin. For information on these, consult thePacific Northwest Insect Control Handbook.

Author: M. T. AliNiazee is an associate professor of entomology, OregonState University, Corvallis.

Acknowledgments: Sincere thanks are expressed to Dr. Glenn Fisher andJoseph Capizzi, Extension entomologists, Oregon State University, fortheir assistance in preparation of this manuscript.

Filbert Insect and Mite Pests

In the United States, commercial filbert pro-duction is restricted to the Pacific Northwestpartly because filbert trees cannot tolerate ex-tremes in dry summer heat or winter cold. Con-sequently, the orchards are concentrated betweenthe western foothills of the Cascade Mountainsand the eastern slope of the Coast Range fromVancouver, Washington, to Eugene, Oregon.

More than 95 percent of this acreage, ap-proximately 24,000 acres, is in the WillametteValley. Washirtgton is the only other state in theUnited States that commercially produces fil-berts and its production is limited to less than1,000 acres, mostly in the Vancouver area. Fi-

FilbertwormMelissopvs latiferreanus (Walsingham)

DescriptionThe adult moths have a wingspread of about

1/2 inch and vary considerably in color. The frontwings may be brown, or almost red. The hindwings are almost black. The most distinctivefeature of this moth is the presence of two goldmetallic bands on the wings.

The worms or larvae have creamy bodies andbrown heads. When full grown, they are 1/2 to5/8 inch long. However, because of the limitedspace available within a filbert nut, the larvaecurl themselves u and often appear shorter thantheir actual length.

Distribution and HostsThe filbertworm, native to the West Coast,

is found across the United States. The larvae havebeen recorded from acorns, wild hazel nuts, Cata-

M. T. AliNiazee

Introduction

Harmful Insects

nancially speaking, the annual filbert productioncontributes between 5 and 10 million dollars tothe economy of the Pacific Northwest.

Because insects and mites cause serious losses,multiple applications of insecticides are oftennecessary. Although there are no detailed esti-mates of economic loss, it is not unusual to findfrom 15 to 20 percent of the nuts damaged byfilbertworm alone in unsprayed orchards. Another5 to 10 percent loss can be caused by the filbertleafroller and the filbert aphid. The overall yieldreduction caused by insect and mite pests inunsprayed orchards has been estimated to beabout 20 percent.

lina cherries, apricots, prunes, chestnuts, and wal-nuts, in addition to filberts.

Based on their morphology, the filbertwormsare divided into seven varieties. The varieties A,B, and C are found west of the Rockies; onlyvarieties A and C are important on filberts.

Life HistoryFilbertworms overwinter as diapausing (mac-

tive) larvae in silk cocoons. The cocoons are foundin leaves and debris on the ground or in cracksand crevices of other shelters including gunny-sacks and packing house sheds. Some larvae hiber-nate 1 to 2 inches below the soil surface.

The larvae pupate within their cocoons andthe adults emerge 2 to 5 weeks after pupationoccurs. Warm temperatures increase the speed ofdevelopment. However, in a normal year, mostof the larvae change to pupae by the end of June.Adults emerge and fly from the middle of Juneuntil the end of October. The emergence of themoth is synchronized with the formation and de-

1

velopment of the filbert nut. In years with favor-able weather, the emergence periods may be longwith two distinct emergence peaks.

Mating takes place soon after emergence andegg laying begins the next day. The eggs usuallyare deposited during the warmest part of the day,on pleasant sunny days. They are laid singly onleaves close to nuts and occasionally on exposedparts of the nut itself. The eggs hatch in 8 to 10days and the larvae search for nut clusters. Theydo little feeding during the searching period. Oncea nut is located, the larva tunnels through thehusk and continues along the filbert shell untilreaching the micropile or soft spot. The nut ispenetrated at this point. Occasionally, nut entryis incomplete, and the larvae moves on to othernuts. Some larvae may die during the entryprocess.

The larvae feed on the kernels by tunnelinginto the centers or excavating a little cavity inwhich to feed. Larval development during thisperiod is fairly rapid, and larvae mature in 3 to4 weeks. Mature larvae may leave the nut either byenlarging the entrance hole or by making a newopening on the side of the nut. Larvae that haveleft the nut then form a cocoon where they spendthe winter either in the soil or on ground debris.A few of the early emerging larvae pupate soonafter cocoon formation and may emerge as adultsin September.

DamageDamage is caused by larvae feeding on kernels

within the shell. Soon after hatching, the younglarvae seek nut clusters and enter the nuts. Duringthe search, they do a little feeding mostly on thenut surface. This forms superficial entrance gal-leries, which are visible even at harvest. In ad-dition to direct damage caused by the larval feed-ing on nut meats, considerable expense is incur-red in sorting to separate the wormy nuts fromthe clean ones. Most of the damage is causedduring July and August.

2

Detection and ControlBlack light traps are used to detect the first

moth emergence in the Willamette Valley. CountyExtension agents and Oregon State UniversityDepartment of Entomology scientists monitor theemergence and flight of these moths through thegrowing season and provide flight information togrowers. Insecticide is applied to filbert orchardswithin a few days after filbert moths have beencaught with consistency in the black light traps.Because of the prolonged moth emergence andlong flight periods, a second application may benecessary not later than three weeks after thefirst. Trap records in the Willamette Valley indi-cate that the first fiibertworm moths of the seasonhave been caught in traps as early as the secondweek in June and as late as the end of July.

Filbertworm infestations usually arise fromwithin an orchard or a nearby packing shed,consequently, sanitation plays an important rolein control. Many of the nuts that drop prematurelycontain worms. Destruction of these nuts elimi-nates worms which would become a source ofinfestation for the next year. Thorough cleaningof drying and packing sheds is essential to avoidfuture infestations.

More than a dozen parasites have been rearedfrom fiibertworms, but none seem to be importantenough to control filbertworm populations belowdamaging levels. Most larval parasites are ineffec-tive once the larvae are inside the nut. The eggparasites, Trichogramma minutum and T. evanes-cens, have proven effective in an experimentaltrial. However, the widespread use of these waspsmay not be practical. Chemical control is still themost effective technique against this pest. A num-ber of chemicals are registered against this insect,and are discussed in the PNW Insect ControlHandbook.

Filbert AphidMyzocallis coryli (Goeze)

DescriptionFilbert aphid are small, soft-bodied, and light

to dark green in color. Most aphids are wingless,except for wing forms. Adults are approximatelyone-tenth inch long and nymphs are about halfthe size of adults. Eggs are pale yellow whenfirst laid, and turn to shiny black before hatch-ing in the spring. They are oval in shape and roundat both ends. Newly hatched nymphs (young)vary in color from white to pale yellow.

egg p

larvapupa

adult

damage

J F M A M .1 J A S 0 N 0

Distribution and HostsThe filbert aphids was first described in

Europe in 1778. In the United States, it was notfound until 1903. Now, the aphid is distributedthroughout the filbert-growing areas of the PacificCoast. It is found on both cultivated and wildhazelnuts. Occasionally, it is recorded from alder,birch, hornbeam, and ash.

Life HistoryIn the Willamette Valley, this aphid over-

winters as an egg that hatches early in the spring.Egg hatch may begin as early as March 1 andcontinue for 3 to 4 weeks. The young aphids whichemerge from the overwintering eggs are calledstem mother nymphs. They molt four times andproduce winged adults that give birth to youngaphids without: sexual reproduction. Upon matura-tion, aphid populations build up rapidly in thespring particularly during cool, moist weather.In July and August, aphid numbers decline be-cause of high temperatures.

In the fall, the aphids develop a generation ofwinged forms. The winged aphids produce theegg-laying forms that occur in October and de-posit the overwintering eggs on the tree trunk andbranches.

DamageDamage is caused by large numbers of aphids

feeding on the foliage and removing plant sapwith their sucking mouthparts. In early spring,the filbert aphids can be found on unfoldingbuds; later they occur on the undersides of leaves.All stages of leaf growth may be infested, althougha slight preference is seen for younger leaves.Aphids occasionally may be found on young nutsand husks. Feeding damage reduces tree vigor,and quality of the nuts produced. Aphids alsosecrete large quantities of honeydew which maycause severe leaf burn, scorch, or staining of thenuts.

egg

nymph

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J F M A M J J A S 0 N 0

Detection and ControlOverwintering eggs can be detected by a care-

ful examination of tree trunks and major branches.

This provides a good indication of potential in-festation levels. Inspection of the terminal growthof trees for the presence of aphids in the springand early summer is the most effective way ofknowing the extent of the problem. Most aphidswill be on the tender stems and the undersidesof leaves. Although no economic injury levelshave been determined for this pest, it seems thattrees can easily tolerate 5 to 10 percent infesta-tion of terminals in early season. In July andAugust, as much as 20 percent infestation willhave little or no impact on the quality or quantityof the nuts produced. Moreover, because ofwarmer temperatures, a sharp decline of popula-tion is expected during these months.

Aphids may be controlled biologically by otherinsects such as syrphid fly larvae, lady beetles,mind bugs, lacewings, and a number of parasites.(See beneficial insect section for a detailed de-scription of these predators and parasites.) Whenchecking for aphids, look for these predators. Be-fore making a final decision on spraying, checkthe orchard to see if the aphids are decliningand to see whether the predator numbers are largeenough to give economic control. Dormant spraysto control eggs normally are more helpful thansummer sprays because they have no harmfuleffects on predators. No sprays are required afterJuly for aphid control.

Filbert LeafrollerArc hips rosanus (L.)

DescriptionAdults are buff colored with dark, irregular

markings on wings. The eggs are laid in masseson the tree bark and overlap each other like fishscales. They are light green when laid, but turnto creamy white by spring. The young larvae arelight green with a distinct dark brown head.Mature larvae are approximate1y three-fourths ofan inch long and vary from light to dark greenwith dark brown heads. Parasitized or diseasedlarvae normally turn brown and are not as activeas healthy ones.

Distribution and HostsThe filbert leafroller is a native of Europe and

was accidentally introduced to the Northwest3

4

4

about 1915. It is well distributed throughout Ore-gon. Initially a pest of many ornamentals, thefilbert leafroller has now become a serious pest ofmany tree fruits including filberts in Oregon andWashington. It feeds on a large variety of shrubsand trees. In Oregon, it has been found on apple,pear, cherry, plum, filbert, and many other fruittrees.

Life HistoryThe filbert leafroller overwinters as an egg.

Eggs hatch in late March or early April depend-ing on spring temperatures. The young larvaemove to opening buds and feed on both sides ofnew leaves. Sometimes they web, developing budsand young foliage to form feeding nests. Thelarval period is about 6 to 8 weeks. Pupation oc-curs within the rolled and webbed leaves. In theWillamette Valley, pupation occurs at the end ofMay and early June, and lasts about two weeks.Adult emergence occurs in the second week of

Leaf rolled by the filbert leafroller

An egg mass of the filbert leafroller

4

June, and usually continues until mid-August.Adults live for 2 to 4 weeks. Most egg laying oc-curs in June and July with an average of 50 eggsper female; the egg masses usually are found ontree trunks and major branches.

DamageLarvae feed on developing buds and immature

nuts and can deform them causing direct losses.They also feed on leaves, tender terminal growth,newly formed nuts, and catkins. After hatchingthe young, larvae fold one or more leaves togetherand feed on the leaf tissue inside this shelter.Foliar damage is not serious unless the larvalpopulation is very large.

Detection and ControlOverwiritering egg masses are laid on main

branches and trunks, consequently, a survey ofthe tree trunks during the winter and early sum-mer will indicate a potential infestation. Earlyspring counts of infested buds also provide a goodindication of the population. Fifty open buds pertree should be examined to arrive at a reasonablyaccurate estimate of infestation levels. At least10 trees selected at random should be examinedper acre. A population level of 10 percent war-rants treatment. Filbert leafrollers may be con-trolled with insecticides applied immediately afterthe hatch of overwintering eggs in early spring.A microbial insecticide, Bacillus thuringinsis, iseffective in controlling this pest, but timing ofthe application is critical. This material is onlyeffective when applied immediately after egghatch begins.

A number of natural enemies have been notedin filbert orchards. The most common ones arewasp parasites which build up near the end ofJune and in most years greatly reduce the leafrollerpopulation. As much as 70 percent parasitism hasoccurred in some orchards.

egg -4

larvapupa

adult I )damage

M A M J J A S a N 0

Adult filbertworm moth Fiilbertworm damage to nuts

N

Filbert aphids Damage caused by filbert bud mites

5

Filbert leafroller larvae Obliquebanded leafroller damage

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Obliquebanded LeafrollerChoristoneura rosaceana (Harris)

Description

Moths are reddish brown in color with twooblique bands on the forewings. The wingspread isabout one inch. When at rest, with wings foldedover the back, the moth's length varies fromseven-sixteenth to five-eighth of an inch. Eggs arelight green and shingled so they overlap eachother like fish scales. Young larvae are lemonyellow with black heads. Older larvae vary incoloration from gray to dark green. Full grownlarvae measure about one inch long. The pupaeare dark, reddish brown and usually are found infolded leaves.

Distribution and HostsThe obliquebanded leafroller is a relatively

new pest on filberts. It first caused noticeabledamage to filberts in 1973 near Salem, Oregon.Since then it has become a secondary pest offilberts throughout much of the filbert-producingregion. Larvae feed on the foliage of a numberof crops including many trees and small fruitssuch as apples, pears, peaches, prunes, straw-berries, and raspberries.

Life HistoryThe insect overwinters as an inactive and

partially grown larva in cracks and crevices oftree bark and debris on the ground. In the springas the temperatures warm, the larvae becomeactive and feed on buds and foliage. Pupationrequires 4 to 6 weeks and usually occurs on theleaves. Adults emerge from early June throughthe middle of July. A sharp emergence peak oc-curs near the middle of July. Egg laying begins afew days after adults emerge and eggs hatchwithin two weeks. Young larvae usually can befound in orchards by the first week of July anddamage is evident by mid-July. Larvae feed anddevelop for 6 to 8 weeks depending on tempera-ture. Pupation occurs inside silk webs and adultsof the second generation emerge in 1 to 2 weeks.Second generation adults usually emerge from thefirst week of September through early October.Eggs laid by these adults hatch in 7 to 10 days.Larvae feed for a brief period and then over-winter until spring.

DamageLarvae feed on leaves, but their primary dam-

age is from feeding on the nut shell underneaththe husk. This feeding causes scarring and stainingof immature nuts and premature drop. Some in-fested nuts do not mature and are unmarketable.In some heavily infested orchards, damage causedby this insect can be as serious as that caused byfilbertworms. Up to 30 percent nut drop has re-sulted from damage by this pest.

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Detection and ControlObliquebanded leafroller infestations can be

detected by periodic examination of filbert clustersstarting in early June. Examining about 500 to1,000 nut clusters per acre gives a good indicationof the infestation level. Brown rot infected clustersshould be examined closely to determine whetherany webbing or larval feeding damage is visible.Recent studies indicate that many nuts presumedto be infected by brown rot organisms are infestedby obliquebanded leafroller larvae. Adults can bedetected by pheromone traps. These traps shouldbe used at a rate of two per acre for determiningemergence dates and population levels. Trapsshould be placed in the orchard in the latter partof May and checked twice a week for about eightweeks. No correlations have been established be-tween the number of moths trapped vs. damageat harvest, but it is evident that trap catches ofmore than 10 moths per week per trap indicatetrouble in the orchard. Pheromone traps also canbe used to determine proper timing for insecticideapplications.

Filbert Bud MitesPhytoptus avellanae Nalepa

and Cecidophijopsis vermiformis (Nal.)

Description and DamageFilbert bud mites are nearly translucent, cigar-

shaped microscopic organisms. Because of theirsize, they cannot be seen with the naked eye butcan be detected by the damage they cause. Dam-age is most severe on loose budded varieties such as

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F M A M J J A S 0 N 0

Daviana, Royal, Fitzgerald, and Nonparel. Barce-lona, the most common variety in the Northwest,is highly tolerant to mite infestations. The mitesdamage female flowers as well as leaf buds.Catkins of Barcelona are often infested, but themites have not been observed on catkins of thepollinizers, such as Daviana and Royal. The dam-aged buds (both vegetative and fruiting) swellinto typical big buds as a result of mite feedinginside. These big buds dry up and eventuallyfall. Infested flowers do not produce fruit. Catkins,when attacked by mites, are distorted, becomingrigid and brittle, and produce little or no pollen.

Distribution and Life HistoryObservations indicate that these mites are dis-

tributed throughout the nut-growing areas of Ore-gon, and commonly are found on wild hazel. Bothbud mite species cause "big bud" symptoms, butat different times. The "big buds" caused byP. avellanae occur from February through June.During the same period when big buds open andstart to dry, the nymphs (young) of P. avellanaeand the adults of C. vermifo'rmis leave the budsand migrate to new axillary buds. Migration isweather dependent, but a majority of the migra-tion occurs during April and May. The two mitespecies feed and multiply rapidly in new axillarybuds, and this results in the C. vermiformis "bigbuds" during July to November. As infested budsfall, C. verimformi larvae move to P. avellanaeinfested buds. At this time P. avellainae opula-tions start to increase and by late winter and earlyspring the "big buds" caused by P. avellanae showup and the cycle continues for another year.

a aupllaOobig bud

Normalbtd * buds a

May

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buds, migrate to naroaoillari,, (March-May)

Blasted buds all(August-

December)

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eamifaaesisbig bud (July-

Nooacrrbec)

ControlControl can be obtained using effective chemi-

cals in the spring when the mite species migrate.Consult the Pacific Northwest Insect ControlHandbook for materials and rates. Phytoseiid mitespecies are common predators of these pests, butthey do not give economic control. Growing re-sistant varieties such as Barcelona is an effectiveway to reduce these mites.

Filbert Nut WeevilCurculio uniformis

Description and DamageAdults are about one-fourth of an inch long

and brownish-yellow. The head bears a slenderbeak about one half as long as the body whichcurves downward. The legless larvae are whitewith brown heads. The nut weevil is a minor pestof filberts. Serious damage has not been observedfor years.

This weevil normally infects acorns. The adultweevil drills holes through the shell of the acornand deposits one or more eggs. As many as fivelarvae have been observed in a single acorn. Adultsare present in July and August. The larvae matureabout the time the acorns begin to drop. Theyusually remain in the acorns during winter. Theyleave the nuts and enter the soil in early spring.Pupation occurs in July. There is one generationa year.

ControlControl measures have not been developed for

this insect and during recent years no control hasbeen needed.

Scale Insects

Description and DamageTwo species of scale insects have been found

attacking filberts in Oregon. The European fruitlecanium, Lecanium corni Bouchi is often the mostdestructive species. L. excrescens Ferris is thelargest scale occurring in Oregon. It is globularand a third of an inch in diameter. It is brownand covered with a white powdery substance, Itis not a native insect and may have originated inone of the Asiatic countries. Lecanium excrescensdoes not appear to be as widespread as L. corni.

7

tJorrnal buds loonshoots (March-May) uruoum buds

a Ilauao bud,espand raptdly

/ remain ,rrollV (March-July)

a gygllsgmg big bud,upandirg with or Cnruhrrrrts louse bbiared budabihour Cusmifgyosrj, migrate rodtn'eIlrnaa bds(A-

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a usell maaddtspopoIotusr, ironer,,,

(July-March)

Life cycle of the filbert bud mites (courtesy of Dr. C. W. Krantz)

8

Lecanium scales

Life HistoryLecanium corni is almost hemispherical, shiny

brown, and a little more than one-eight of aninch in diameter. The winter is passed in a half-grown condition. Adults develop early in May.Eggs are found beneath the parent scales in largenumbers in May and June. Eggs hatch during Julyand early August and young scale crawlers moveto leaves where they feed by sucking plant juices.In late summer they move back to the twigs wherethey spend the winter. There is one generation ayear.

ControlParasites are important in controlling scale in-

sects and a number of parasites have been re-corded on this pest. Occasionally, insecticidesprays are necessary in some orchards to checkthe scale populations. A dormant spray of sprayoils, plus an organo-phosphate insecticide will con-trol scale with less hazard to natural enemies.

Syneta Beetle

Syneta albida Lee.

Description and DamageSyneta beetles are small, soft-bodied, light gray

to dirty white, and one-fourth of an inch long.They are native to the northwest, and occur onoak, alder, willow, and many other trees. Thedamage is caused by adult beetles feeding onyoung foliage, buds, and immature nuts. They area secondary pest of filberts and rarely require anychemical control.

Syneta beetle adult

Life History and ControlThe adult beetles emerge from the soil in late

April and early May, and are active for 4 to 6weeks. The females deposit eggs on the groundwhich hatch in 2 to 3 weeks. Young larvae burrowin the soil and feed on fine fibrous roots of trees.Feeding continues through the summer and fall.The larvae remain in the soil until the next spring,turn into pupae, and later emerge as adults.

This insect is very susceptible to most insecti-cides. The timing of spray application, is de-termined by using ground emergence cages.Treatments should be applied in early May toget effective control.

Eyespotted Bud MothSpilonata ocellana

Description and DamageThe eyespotted bud moth is an important pest

of many fruit trees in the United States. Oc-casionally, it has been observed causing damageto young filbert trees. The larvae appear in earlyspring and feed by webbing young leaves andopening buds. The adults are smaller than thefilbert moth, grayish-white with a cream whiteband across both wings. Larvae are chocolatebrown with shiny black heads and are about one-half inch long when mature.

Life Cycle and ControlOlder larvae hibernate in small silken cocoons

on twigs near the buds. They emerge early thefollowing spring, feed, and then pupate withincurled leaves. Adults appear in June. The eggsare laid on leaves within a few days after emer-

gence. The eggs hatch, and larvae feed on foliageuntil fall, then hibernate. There is one generationper year.

Delayed dormant sprays of oil or oil plus in-secticide gives good control. A June application ofregistered compounds is also useful. Consult thePacific Northwest Insect Control Handbook fordetails.

Eye spotted bud moth adult

Tree CricketsOecaiithus niveus (DeGeer) and

0. nigricornis (F, Walker)

Description and DamageTwo species of tree crickets, Oecanthus niveus

and 0. nigricornis F. Walker, have been found onfilberts. Adult crickets are usually pale yellow orbrown. Occasionally, 0. nigricornis adults are al-most black. The young are nearly white. Bothyoung and adults are predaceous, feeding onscales, aphids, and other insects. At times, theyfeed on leaves and flowers of various plants. Oftenyoung fruits, especially peaches, are badly scarredby tree crickets.

Life HistoryAdult tree crickets imbed their eggs in tender

young twigs. On young filbert orchards this maybe damaging. A scarred condition of filbert nutssomewhat resembling tree cricket injury topeaches has been noticed. The condition has beenobserved in varying degrees since 1930. Scarringof the nuts, although it has not caused substantiallosses, has been increasing somewhat. The scarredcondition of the nuts reduces their grade.

Ambrosia BeetleAnisandrus pyri (Peck)

Description and DamageThis small, black beetle, often referred to as

shot-hole borer, sometimes attacks filberts. The in-jury is recognized by the small shot-hole entrancesof the beetles. This insect belongs to the groupknown as Ambrosia beetles. Their larvae feed ona fungus planted by the beetles in the tunnels.The fungus grows only in trees that have a soursap condition. There are several causes of soursap such as winter injury, drought, arid lack ofdrainage.

Adult beetles are active during March, April,and May. They burrow into limbs or trunks oftrees. Eggs are laid on the sides of the burrowsand on cross tunnels.

ControlSince beetles attack only trees that are in a

sour sap condition, every possible means shouldbe used to keep trees growing vigorously and toavoid tree stress. Heavily infested limbs and treesshould be pruned or burned. Registered chemicalsmay be used in the spring to obtain control, butweakened trees often fail to respond to care andare attacked by beetles despite all effort.

Apple MealybugPhenacoccus aceris (Signoret)

Description and DamageThis insect, apparently native to Europe, was

first observed on Oregon filberts in 1951. The applemealybug has been confined to restricted areas innorthern Marion County and western Polk County.

In Oregon, this insect has been found only onfilberts, although other states have reported iton apple, cherry, currants, and hazelnuts. Theinsect feeds by sucking plant juices. It secretes ahoneydew-like material which supports the growthof a black sooty fungus. The young feed on theleaves and tender twigs causing premature drop-ping of leaves and the killing of small twigs.

Although not yet widespread, this insect maybecome one of greater economic importance sinceit has been proven to be the vector for little cherrydisease of cherries.

Life HistoryIn May, overwintering females lay eggs in

masses of about 500 or more. In June, the emerg-

9

ing young (nymphs) crawl to young twigs andleaves where they feed. In the fall, the nymphsmigrate to larger limbs where females overwinteruntil next spring.

ControlControl has been necessary in only a few in-

BeneficialA number of beneficial insects are found in

filbert orchards. They play a major role in re-ducing populations of harmful insects. In the caseof the filbert aphid, they are the primary modeof natural control and are very effective underundisturbed conditions. Some of the more commonones are described here. Growers should avoidunnecessary kill of these insects.

Lady BeetlesHip podamia convergens,

Coccinella transversoguttata, and others

Description and Life HistoryA number of lady beetles are found in filbert

orchards; the most common is the convergent ladybeetle, H. convergens. Adults of convergens andtrarisversoguttata, are about one-sixth inch long,oval, and reddish-orange with black spots. Thelarvae are gray or bluish-gray with a number ofyellow and orange spots, and are alligator-shaped.Eggs are spindle-shaped, yellowish-orange, and arelaid in clusters on the undersides of leaves.

Adult lady beetles overwinter in colonies inwoodland and mountain areas. They migrate toorchards in early spring where they feed onaphids, and begin egg laying within a month. Eggs

Lady bug

10

stances. Indications are that recommended treat-ments for the control of aphids also are effectiveagainst the nymphs of the apple mealybug. Thesesprays should be applied in June when youngnymphs are migrating to the leaves and twigs.Delayed dormant sprays of supreme type oil havegiven good control.

Insects

Lady bug larva

hatch in 8 to 15 days, depending on the tempera-ture. Larvae also feed on aphids and pupate withina 4- to 8-week period. Adults emerge within aweek, and the cycle continues. A complete cycletakes from 5 to 10 weeks depending on the tem-perature.

BenefitsBoth adults and larvae are voracious feeders,

feeding on a number of soft-bodied insects. Theyseem to prefer filbert aphids. Female beetles eata large number of aphids (about two aphids perday) after depositing eggs. Under favorable con-ditions, lady beetles can reduce the populationof aphids to low numbers.

Syrphid FliesSyrphus opinatar, and other species

Description and Life HistoryThis group includes some important predators

of aphids. The adult flies are about one-fourth toone-half inch long, and banded with yellow, blackor white bands. They are swift fliers, and hoverover flowers. Adults feed on pollen and nectar. Thegreen larvae feed on soft bodied insects. They

Li

Syrphid fly

Syrphid maggot

resemble small slugs with tapered front ends andare about one-half inch long. The eggs are whitishwith faint longitudinal ridges.

Syrphid flies overwinter as pupae in the soil orin the trash underneath the trees. Adults are firstseen in May and June. The eggs are laid on theleaves and larvae appear within a week to 10 days.The larvae feed on aphids for about two weeks,then drop to the ground for pupation. A completelife cycle during summer months can be com-pleted within a 4- to 5-week period. There areabout 3 to 7 overlapping generation per year.

BenefitsThe larvae are voracious feeders on almost all

soft-bodied insects, particularly the filbert aphids.A large number of aphids may be consumed by thelarvae before completing the developmentalperiod. The larvae seize the aphids with theirmouth parts and suck out the body sap. In filbertorchards, syrphids are quite common and are use-ful in reducing aphids.

Green LacewingChrysopa spp.

Three different species of green lacewingscommonly are found in filbert orchards. Adultlacewings are delicate insects measuring aboutone-half to three-fourths of an inch. The greenlacewing adults are green to greenish-yellow andbrown lacewing adults usually are brown tobrownish-yellow. The eggs of green lacewing arealmost white and are laid singly on a long slenderstalk. The eggs of brown lacewing are glisteningwhite and are laid on a short stalk. The larvae arealligator-shaped, gray to yellowish-gray and areabout three-fourths of an inch long when mature.

Lacewings overwinter as pupae usually in pro-tected places such as cracks and crevices. Adultsemerge in early summer and lay their eggs onthe foliage. The eggs hatch in 1 to 2 weeks andlarvae feed on soft-bodied insects, aphids, mites,and scales being preferred. The number of gen-erations per year depend on the prevailing tem-perature. Under favorable weather conditions, asmany as six generations may be completed in ayear.

Lacewing

Lacewing larva

BenefitsAdults are honeydew feeders but larvae are

insect predators. They are effective predators ofa number of pest species including aphids, mites,scales, immature bugs, and leafhoppers. In filbertorchards, they are effective in reducing filbertaphids.

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Mind BugsDescription and Life History

Two species of mind buds are common preda-tors of filbert aphids. These are Deraeocorisfasciolus Knight and Heterotoma sp. Both feedon filbert aphids. Little is known about the biologyof these insects. D. fasciolus overwinters as eggsand the nymphs appear in early summer. Adultsare abundant in June arid July. They are small,about one-eight to one-fourth inch long, lightbrown to dark brown. The Heterotoma adults arebrown to light black and also are seen in largenumbers in July and August.

BenefitsBoth species are predatory on aphids. Although

they seem to be abundant in many WillametteValley orchards, no comparative data are availableon their effectiveness.

ParasitesIto plectis quadricingulata (Prov.)

Ischnus inquisitorius atriceps (Cresson)Brachymeria ovata (Say)

Micro gaster epagoges (Gahan)Ascogaster quadridentata (Wesm.)Habrocytus phycidis (Ashmead)

Hemisturmia tortricis (Conquered)Aplomya caesar (Aid)

Trichograma minutum (Riley)

Description and Life HistoryA number of naturally occurring parasites play

an important role in reducing the population offilbert aphids, filbert leafrollers, and the filbert-worm. They parasitize eggs, larvae, and pupae ofall major filbert insects.

The parasites belong to two groups, the waspsand flies. They range in size from .01 to .5 inch.

Adult hymenopterous parasite

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The size of a parasite is related to the stage orsize of the host insect attacked. For instance, theegg parasites are minute, while the larval pupalparasites can be as big as one-half inch. Theparasites usually lay the eggs either inside or out-side the host body and upon hatching the larvae,feed in or on the host. Many parasite larvae canfeed on one single individual. The most visiblestages in the field are parasite larvae and adults.The pupae of Tachinid flies also are visible. Thelife cycle of all parasites is well synchronized withthe life cycle of the hosts, but varies significantlyfrom species to species.

BenefitsThe parasites are very effective against the

filbert leafroller. Although a number of parasitesexist against the filbert aphid and filbertworm,apparently they are not very effective. Most 'para-site larvae feed on host reproductive organs,muscles, and fat bodies, leaving the shell of thehost insect. The parasitized insects frequently areobserved under field conditions covered with tinyparasite cocoons or, in the case of aphids, themummified aphids.

Parasitized filbert leafroller pupae (arrow indicates a parasitecocoon)

Predator MitesTyphiodomus arboreus, K. abbarrans

Description and Life HistoryThese two predatory mites are quite common

on Oregon filberts. Both feed on a number oferophyid mite species including filbert rust mitesand bud mites. They are small (.01-.03 inch),pear-shaped mites with slightly flattened bodies.They overwinter as adults and appear early inthe spring waiting around the opening buds tocatch migrating bud mites. Large numbers of

predatory mites are seen in March and Aprilaround the exterior of a filbert bud mite infestedbud. There are 5 to 6 generations of predatorymites per year.

BenefitsIn spite of their feeding, these mites are unable

to control filbert bud mites on susceptible varieties.The rust mites normally are not a problem onfilberts, and it is not known whether the predatorymites contribute to their control. No spider mitesare pests of filbert trees.

Almost all registered insecticides are toxic tomany predators and parasites. Care should betaken in selecting insecticides. Less toxic com-pounds should be selected and applied at a timewhen natural enemies are not present or leastsusceptible to these compounds. Insecticidesshould be used as a last resort to control pests.

Funds for color photographs in this publication were pro-oWed by the Oregon Filbert Association.

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