Japanese Beetles

Organic Solutions for Japanese Beetles
and May or June Bugs
A Factsheet from Toxic Free NC
AboutJapaneseBeetles
SeveralbeetlesintheScarabfamilycandamagecropsinthe
garden,bothaboveandbelowtheground.Themostwell
knownistheJapaneseBeetle.Relatedbeetlesincludethe
GreenJuneBeetleandtheEuropeanChafer.They’reoCen
calledMayorJuneBeetles.
Managingallthreespeciesissimilar.Thegrubsofthese
beetleseattherootsofgrassesandcropplantsandother
organicmaEer.Theycanbeabigprobleminlawns,andmay
alsoeattherootsofvegetableandstrawberrytransplants,
cornplants,andpotatoes.
Asadults,thesebeetleseatcropleaves,leavingaragged,
lacyor“skeletonized”leaf,wheretheveinsareleCintactbut
theleafymaterialbetweeniseaten.Adultsmayalsoeat
flowersandfruits.Thesebeetlescanweakenplants,damage
fruit,orevenkilltheplant.
TheKpsbelowaredesignedtohelpyoumanageJapanese
BeetleandMayorJuneBeetledamageinyourgarden
withouttoxicchemicals.Sustainablepestmanagement
strategiesusuallyworkbestwhenusedtogether.Think
aboutyourgarden,yourresources,andyourKme,andput
severaloftheseKpstogetherforaplanthatworksforyou.
Grubs.
PhotoCredit:DavidCappaert,MichiganStateUniversity.
Iden1fyingJapaneseBeetles
Allthreetypesofadultbeetlesareblockyinshapeand0.5-
1inchlong.TheJapaneseBeetleismetallicgreenwith
coppercoloredwingsandhastuCsofsmallwhitehairsalong
thesidesofitsbody.
TheGreenJuneBeetle,orJunebug,isiridescentgreen.The
EuropeanChaferisashinybrowncolor,andisbitmore
roundshapedthantheothers.
Thelarvaeofallthreespeciesarecalled“whitegrubs.”They
canbeuptoaninchlong,withbrownheadsandplump,
white,segmentedbodies.Theyhavethreepairsoflegsjust
behindtheirheads,andtheirtail-endsmaylookgray.They
curlupintoaCshape.
AdultJapanesebeetlesondamagedleaf.
PhotoCredit:DavidCappaert,MichiganStateUniversity.
LifeCycle
Thelifecyclesofthesebeetlescanbefrom1–4yearslong
dependingontheytype.Adultsusuallycomeoutofthesoil
inswarmsduringlatespringandearlysummer.Theyeat
plantleavesforseveralweeksandthenlayeggsinthesoil
duringthesummer.Theeggshatchin2–3weeks,andthe
larvaeorgrubseatforawhilebeforespendingthewinter
deepinthesoil.
Inspring,thegrubscometotheupperlayersofsoiltofeed
onrootsandorganicmaEer.Sometypesofgrubspupatein
earlysummerandthencomeoutofthesoilasadults.Other
typesstayundergroundunKlwinterwhentheywill
hibernate.
TheycanrepeatthecycleofundergroundeaKngand
hibernaKngfor1to3yearsbeforethegrubfinallypupates
andbecomesanadultbeetle.
Preven1on
AdultgreenJunebeetle.
Photocredit:ClemsonUniversity-USDACooperaKve
ExtensionSlideSeries
1)Growhealthyorganicplants.Strongplantscanhandle
somebeetledamagebeEerthanweak,strugglingplants.
JapaneseBeetlesandMay&JuneBeetlesmaylikethesmell
ofsickorinjuredplantsandaEackthemfirst.Makesurethat
yourcropsarege^ngenoughsunlightandwaterandthat
thesoiliswell-drainedandrichinnutrientsandorganic
maEer.
2)Timing.Ifyourgrowingseasonislongenoughandthe
weatherallows,youmaychoosetoplantsomequickgrowingplantsinlatesummeraCermostadultJapanese
beetlesandMay&Junebeetleshavefinishedfortheyear.
3)Userowcovers.Keeptheadultbeetlesfromfindingyour
cropbycoveringyourplantswithalightweight“floaKng”
rowcoversuchasReemay.Thismaterial(unlikeplasKcor
heavierfabrics)letswater,air,andsunlightthrough.Youcan
buythematgardensupplystoresororderfromseed
catalogs.Thecoverscanlierightontheplants(theplants
EuropeanChaferadultbeetle.
willliCthecoverastheygrow),oryoucansupportthem
Photocredit:MikeReding&BetsyAnderson,USDAAgricultural
withwirehoops.
ResearchService
ThetrickistokeeptheedgesofthecoversKghtlyburiedorweigheddownsothatthebeetlescannotgetin.Ifyour
cropsrequirepollinaKonbyflyinginsectsinordertoproducefood(squashandothercucurbits,forinstance),youwill
havetoremovetherowcoversperiodicallytopollinatebyhand.
CoveringyourcropworksbestinsoilwhereJapaneseorMay&JuneBeetleshavenotbeenapestinthepast.Ifyou
havegrubslivinginyoursoilalready,rowcoverswillkeepthemininsteadofout!
4)Avoidtraps.PheromonetrapsareoCenrecommendedforJapaneseBeetles,butinasmallgardenthosetrapscan
domoreharmthangood!Keepinmindthatadultbeetlescancomeoutinverylargenumbersallatonce,andthey
movefast.TrapsmightaEractalotmorebeetlestotheareathantheycatch.Forthesamereason,lighttrapsortrap
cropsarenotrecommended.
GeIngRidofJapaneseBeetlesWithoutToxicChemicals
1)Scoutandhandpick.You’lloCenseewhitegrubswhenyouarediggingorKllingthegarden.Whenyoudo,crush
them,sniptheminhalfwithscissors,ordropthemintoapailofsoapywater.Adultbeetlescanbehandpickedfrom
plantsandcrushedordroppedintosoapywater.Youcanalsoputadropclothbeneathyourplantsandthenshakethe
beetlesoutandcollectthemonthedropcloth.EarlymorningisagoodKmetolookfortheadultbeetles,because
whenthey’recoldtheymovemoreslowly.
2)AOractnaturalenemies.SometypesofwaspsandfliesarepredatoryorparasiKctobeetleeggsandwhitegrubs.
Groundbeetlesandsomeantseattheeggs,andbirdsaregoodpredatorsofadultbeetles.Youcanwelcomebeneficial
insectstoyourgardenbyplanKngwildflowersandherbswithsmallflowersforpollenandnectar.Perennialherband
flowerbedsandshrubsnearbythevegetablegardenwillprovideahomeformanyotherhelpfulcreatures.
3)Parasi1cnematodes.ThereareatleasttwospeciesofparasiKcnematodesyoucanbuythatwillaEackthegrubsof
JapanesebeetlesandMay&Junebeetles.Checkgardensupplyandseedcatalogsfortherightspecies,andfollow
theirinstrucKonscarefully.
4)Milkydiseasebacteria.MilkydiseaseistypeofbacteriathatkillsthewhitegruboftheJapanesebeetle.Itmayalso
workforMay&Junebeetlewhitegrubs.Milkydiseaseisnotharmfultoothercreatures.Sporesofmilkydiseasecan
beboughtinproductssuchasMilkySpore™,andappliedtogardensoil.Itmaybeevenmorehelpfultoapplyitto
lawns,perennialbeds,andotherareasnearthegardenthatyoudon’tKll.Youcanfinditingardenstoresorseed
catalogs.BesuretofollowinstrucKonscarefully.Thewhitegrubeatsmilkydiseasebacteria,thendiesandthebacteria
spreadintothesoil,wheretheywillhelpyoucontrolgrubsforseveralyears.Usingmilkydiseasecantakeayearor
twotowork,butonceitdoes,itcanlastforseveralyears.However,milkydiseasewon’tcontroladultbeetlesunless
thewholeneighborhoodusesit!Theadultscanflyandmovefast,sotheyfindingtheirwayfromonegardentothe
nexteasily.
5)UseNeemoil.NeemoilisanaturalproductpressedfromtheseedoftheNeemtree,whichrepelsandkillsmany
typesofinsects.AsalastresortwhenbeetlesareeaKngtheleavesofyourplants,youmightchoosetospraythe
leaveswiththisleast-toxicinsecKcide.DoublecheckanyNeemoilproductontheOrganicMaterialsReviewInsKtute’s
listofproductsapprovedforcerKfiedorganicfarms.Neemoilcankillpollinatorsandother“goodbugs”youwantto
keepinyourgarden,soyoushoulduseasliEleaspossible.Trytosprayintheearlymorningorlateeveningbeneficial
insectsarelessacKve.Obviously,even“organic”sprayscomewithrisksandproblems,sotrytheotherKpsherefirst,
andyoumaybeabletoskipthespraysaltogether.
Sources
Ellis,BarbaraandBradley,FernMarshall,editors.TheOrganicGardener'sHandbookofNaturalInsectandDisease
Control:ACompleteProblem-SolvingGuidetoKeepingYourGardenandYardHealthyWithoutChemicals.Rodale
Press,1996.
Frank,StevenandBambara,S.“ManagementofadultJapanesebeetlesforcommercialnurseryandlandscape
operaKons.”DepartmentofEntomologyInsectNote,NCStateUniversity,NCCooperaKveExtensionService.Revised
June,2009.ViewedMarch,2012:[link]
Bambara,S.“GreenJunebeetlegrubs.”DepartmentofEntomologyInsectNote,NCStateUniversity,NCCooperaKve
ExtensionService.ViewedMarch,2012:[link]
Heller,Paul.“GreenJuneBeetle.”ThePennsylvaniaStateUniversityCollegeofAgriculturalSciences,Entomology
Department.April2007.ViewedMarch,2012:[link]
Murray,Todd.“PestAlert:MoveoverCraneFly;theEuropeanChaferiscoming!”GardenFriends&Foes.Washington
StateUniversity,WhatcomCountyExtension.[link]
“MayorJuneBeetles(Phyllophagaspp.)”UniversityofFlorida,InsKtuteofFoodandAgriculturalSciencesExtension.
August2006.ViewedMarch,2012:[link]
“MayBeetles.”CenterforIntegratedPestManagement,NorthCarolinaStateUniversity,NCCooperaKveExtension
Service.ViewedMarch,2012:[link]
"JuneBeetle.”TexasA&MUniversity,DepartmentofEntomology,AgrilifeExtension.ViewedMarch,2012:[link]
Steinkraus,KH,andTashiro,H.“MilkyDiseaseBacteria.”AmericanSocietyforMicrobiology:AppliedMicrobiology.Vol.
15,No.2,March1967.ViewedMarch,2012:[link]
McGrath,Mike.“MilkySporedisease–doesitpreventlawngrubs?”YouBetYourGardenradioshow:QuesKonofthe
Week.2006.ReprintedbyGardensAlive!ViewedMarch,2012:[link]
Thisfactsheetwaswri-enwiththeneedsofnon-commercialhome,schoolandcommunitygardenersin
mind.Cer:fiedOrganicgrowers,orthoseseekingacer:fica:on,shouldcheckwiththeircer:fyingagency
beforeusingANYinsec:cide.Someorganicallyacceptableinsec:cidesareapprovedforuseinCer:fied
Organicsystemsonlyagainstcertainpestsorincertainsitua:ons.