E-21-W Vegetable Insects - Urban Agroecology

MANAGING INSECTS IN THE HOME VEGETABLE GARDEN

Rick E. Foster and John Obermeyer, Extension Entomologists

Department of Entomology

Vegetable InsectsE-21-W

PURDUE EXTENSION

Insectsfeedingonhome-grownvegetablesareafactoflifeformostgardeners.Gardeners’twochoicesaretotoleratethedamageorattempt toprevent it.Frequently, toleratingthedamageisareasonableapproach.Forexample,whentomatoesbegintoripen,mostgardenershavemoretomatoesthantheycanpossiblyuse.So,caterpillarschewingonafewfruitsarenorealconcern.Cornearwormsusuallyconfinetheirdamagetothetipsofsweetcornears.Aviablestrategyistocutoffthedamagedtipsbeforecookingthecorn. Anotherapproachistoplantcropslesssusceptibletoinjuryfrominsectfeeding.Table1categorizesvegetablecropsasneverorrarely,sometimes,andusuallyoralwaysdamagedbyinsects. Thereareanumberofpracticesthatthehomegardenercanemploytoreduceinsectproblems.

• Properlydisposeofplantresiduesfromthepreviousyear’sgarden.

• Plantvarietiesthatarerecommendedforuseinyourarea,andplantthematthepropertimeforbestgrowth.Plantingtooearlywhenthesoiliscoolmaymaketheplantsmoresusceptibletosomesoilinsects.

• Inspecttransplantsbeforepurchasetomakesuretheyarehealthyandnotinfestedwithinsects.

• Useproperplantspacings,fertilizers,water,andculturalpracticestoinsurevigorousplantgrowth.Plantsthataregrowingvigorouslyoftencantoleratemoreinsectdamagethanpoorlygrowingplants.

• Keepthegardenasweed-freeaspossible.Thiswillhelpthe plants to continue to grow vigorously, and weedsmayharborinsectsthatalsowillattackthevegetables.However, thepresenceofweedsorcompanionplantsmayincreasethenaturalenemypopulation.

• Inspectplantsregularlyforinsectsorinsectdamage.Earlydetectionmeansmoreeffectivecontrolandcanreducethe amount of damage suffered. Particularly in smallgardens,early-detectedcaterpillars,loopers,hornworms,andlargebeetlescanoftenbehandpickedfromplantsanddestroyedbeforetheycauseproblems.

• Treatmost vegetableswith insecticidesonlywhenpestinsectsareobserved;however,treatcertainvegetables,such as cantaloupes, cucumbers, and squash, on apreventivebasistoavoidseriousdamage.

INSECTICIDES Several types of insecticides are available for homegardeners.Table2 lists the insectsmost commonly foundonvegetablesandtheinsecticidesrecommendedtocontrolthem.Thefollowingsectionsdescribe thevarious typesofavailableinsecticides.

Botanical Insecticides (extracted from plants) Neem:Theactive ingredient inNeem,azadirachtin, isderivedfromleavesorseedsofneemtrees.Ithasactivityagainstavarietyofinsectpests.Formanypests,neemactsasarepellent,ratherthanatoxicant.Therefore,itisimportanttoapplyneembeforeaseriousinfestationispresent. Pyrethrum is derived from the flowers of certainchrysanthemums. It causes rapid paralysis and apparent

TABLE 1. Frequency of Insect Damage to Various Vegetables Grown in the Home Garden

Never or Rarely Sometimes Usually or Always

Carrot Asparagus Broccoli

Greenonion Bean Cabbage

Lettuce Pepper Cantaloupe

Pea Spinach Cauliflower

Radish Tomato Cucumber

Eggplant

Potato

Squash

Sweetcorn

2Managing Insects in the Home Vegetable Garden — E-21-W

death, but insects may subsequently recover. Pyrethrumprovidescontrolforupto1dayandismosteffectiveagainstsoft-bodiedinsectssuchasscalesandaphids.

Microbial Insecticides Microbial insecticides available to the home gardenercontainsporesof thebacteriumBacillus thuringiensis (Bt),whichparalyzestheinsect’sgutafterbeingeaten.ABtstraineffectiveagainstmanycaterpillarsissoldasDipel,Javelin,MVP,etc.StrainssoldasM-TrakorNovodorareeffectiveagainsttheColoradopotatobeetle.Microbialinsecticidesarenottoxictobeneficialinsects,humans,orothervertebrates.Spinosadisarelativelynewfermentationproductthathasgoodactivityagainstmostcaterpillars,Coloradopotatobeetles,andthrips.

Manufactured Insecticides Carbaryl (Sevin)isawidelyusedinsecticidewithseveraltradenames.Itiseffectiveonbeetlesandsomecaterpillarsbutdoesnotkillaphids.Carbarylispersistentonplantsfor3-4days,butmaycauseoutbreaksofaphidsandspidermitesbykillingnaturalenemies. Malathion ismoderately effective on a wide range ofinsects,especiallysuckinginsects.Itispersistentonplantsfor2-3days. Several pyrethroid insecticides (bifenthrin, cyfluthrin, esfenvalerate, lambda cyhalothrin, and permethrin) areavailable ffor homeowners to use on vegetables. Theseproductsaresoldunderavarietyoftradenames,sobesuretochecktheactiveingredientonthelabel.Thecropsincluded

TABLE 2. General Garden Pests Commonly Found on Vegetables and Recommended Insecticides to Control Them.

Pests Vegetables Attacked Recommended Insecticides*

Aphids Manyvegetables 2,4,9,11,13,14

Asparagusbeetle Asparagus 3,9,15

Beanleafbeetle Bean 2,3,8

Blisterbeetle Manyvegetables 2,3,8,11

Cabbagelooper Cabbage,cauliflower,broccoli 1,2,5,8,12,15

Coloradopotatobeetle Potato,tomato,eggplant,pepper 1,2,5,8,12,15

Cornearworm/fruitworm Corn,tomato,bean 1,2,3,4,5,8,12,15

Cucumberbeetle Bean,cucumber,melon,squash,pumpkin 2,3,8

Cutworm Manyvegetables 2,3bait,5,8,12

Europeancornborer Corn,pepper,bean 1,2,3,4,5,8,12,15

Fleabeetle Manyvegetables 2,3,4,5,8,12

Grasshopper Manyvegetables 2,3,5,8,11

Importedcabbageworm Cabbage,cauliflower,broccoli 1,2,5,8,12,15

Japanesebeetle Manyvegetables 2,3,5,8,11,12

Leafhopper Bean,potato 2,3,5,8,11,12

Mexicanbeanbeetle Bean 2,3,4,5,8

Slugs Manyvegetables 6,10

Squashbug Cucumber,melon,squash,pumpkin 2,3,5,12

Squashvineborer Squash,pumpkin 2,3,5,12

Tarnishedplantbug Manyvegetables 2,3,4,5,8,9,12,13

Tomatohornworm Tomato,potato,eggplant,pepper 1,2,3,4,5,8,12,15

Twospottedspidermite Manyvegetables 2,7,9

Whitefly Manyvegetables 2,5,9,11,13

*1.Bacillus thuringiensis(Dipel,Javelin,M-Trak,etc.)9.Malathion2.Bifenthrin10.Metaldehyde3.Carbaryl11.Neem4.Cyfluthrin12.Permethrin5.Esfenvalerate13.Pyrethrins6.Ironphosphate14.Soap(insecticidal)7.Kelthane15.Spinosad8.Lambdacyhalothrin

3 Managing Insects in the Home Vegetable Garden — E-21-W

onthelabelvary,sobesurethatthecropyouaretreatingislistedbeforeyouspray.Allofthepyrethroidsareextremelyeffective insecticides that will provide up to 7-10 days ofcontrolofawidevarietyofpests.TheywilleffectivelycontrolColoradopotatobeetlesthatareresistanttoinsecticidessuchasSevin.Pyrethroidsareextremelytoxictofish,socautionshouldbeusedaroundbodiesofwater.Pyrethroidsarealsotoxictohoneybees.Inorganic Insecticides (oils and soaps) Horticulturaloilsworkonlyoncontactandhavenoresidualactivity.Commerciallyavailableinsecticidalsoaps,whicharemadefromnaturallyoccurringfattyacids,helpcontrolaphids,leafhoppers,mites,scales,andwhiteflies.Likeoils,soapsonlycontrolthoseorganismsonwhichthespraylands.

Some Notes About Insecticides• Althoughmostinsecticidesavailableforuseinthehomegardenarerelativelysafetouse,theyareallPOISONS andshouldbeusedwiththeutmostcare.Carefully read and follow all precautions on the insecticide label.Table3liststhenumberofdaysyoumustwaitaftertreatmentbeforeharvesting thevegetables.Vegetablesshouldbethoroughlywashedbeforetheyareeatenorcooked.

• Sometimes using an insecticide will increase insectproblems.Forexample,overuseofcarbarylonsomecropscanincreaseproblemswithaphids,mites,andwhitefliesbecauseitkillsthenaturalenemiesthateatthosepests,butdoesnotkillthepeststhemselves.

TABLE 3. Harvest Restrictions in DAYS for Common Vegetable Insecticides

Vegetable

Days After Treatment to Wait Until Harvest

Bac

illu

s

thu

rin

gie

nsi

s

Bif

enth

rin

Car

bar

yl

Cyfl

uth

rin

Esf

enva

lrat

e

Lam

bd

a C

yhal

oth

rin

Mal

ath

ion

Nee

m

Per

met

hri

n

Pyr

eth

rin

s

Sp

ino

sad

So

ap

Asparagus 0 NO 1 NO NO NO 1 0 1 0 60 0

Bean 0 3 3 7 A B 1 0 NO 0 3 0

Beet 0 NO 7 0 NO NO 7 0 NO 0 NO 0

Broccoli 0 7 3 0 3 1 3 0 1 0 1 0

Cabbage 0 7 3 0 3 1 7 0 1 0 1 0

Cantaloupe 0 NO 3 0 3 NO 1 0 0 0 3 0

Carrot 0 NO 7 0 7 NO 7 0 1 0 NO 0

Cauliflower 0 7 3 0 3 1 7 0 1 0 1 0

Cucumber 0 3 3 0 3 NO 1 0 0 0 1 0

Eggplant 0 7 3 7 7 5 3 0 3 0 1 0

Greenonion 0 NO NO NO NO 14 3 0 1 0 NO 0

Leaflettuce 0 7 14 0 NO 1 14 0 1 0 1 0

Peas 0 14 3 NO A B 3 0 NO 0 3 0

Pepper 0 7 3 7 7 5 3 0 3 0 1 0

Potato 0 21 7 0 7 NO NO 0 14 0 7 0

Radish 0 NO 7 0 7 NO 7 0 NO 0 NO 0

Spinach 0 NO 14 0 NO NO 7 0 1 0 1 0

Squash 0 3 3 0 3 NO 1 0 0 0 3 0

Sweetcorn 0 1 2 0 1 1 5 0 1 0 1 0

Tomato 0 1 3 0 1 5 1 0 0 0 1 0

NO-NotlegalforuseonthiscropA-3daysforfresh,21daysfordriedB-7daysforfresh,21daysfordried

4Managing Insects in the Home Vegetable Garden — E-21-W

• When properly applied, sprays and dusts should giveadequatecontrolofinsects.Plantsneedonlyalightcoatingofdust,butitmustbeonboththeupperandlowerleafsurfaces.Becauseofthis,shaker-candustersusuallydonotdoanadequatejob.Squeezeorplungerdustersprobablyarebetter,asareaerosoldusters if keptagitatedwhiledusting.Dustswillusuallybemoreexpensiveperounceofactiveingredientthansprayformulations.

•Whenspraying,bothupperandlowerleafsurfacesmustbetreated.Sprayerpressuremustbesufficienttorollleavesover.Aerosol cans of insecticide are not recommendedexcepttotreatindividualplantsorverysmallgardens.Unlessotherwisenotedonthemateriallabel,agallonofspraywillcoverapproximately500squarefeetor200feetofrow.

•Whenusedproperly,theinsecticidesavailableforusebyhomegardenerswillnot leavesufficientresiduesontheproducetocauseanyadversehealtheffects.Asanaddedprecaution,gardenersshouldrinseanyproducewithcleanwaterbeforeconsumingit.Thiswillalsohelpwashawaydirtandotherdebris.DO NOTwashvegetablesinsoapywater.Soapcanbedifficulttoremoveandhasnotbeentestedforsafetywhenconsumed.

ORGANIC GARDENING Although properly used insecticides do not adverselyaffecthumanhealth,somegardenersnonethelesschoosetogrowtheirvegetablesorganically.“Organic”meansthatnochemicalfertilizersorsyntheticpesticidescanbeused.Theuseofcertainpesticides,suchasBacillus thuringiensis,oilsandsoaps,pyrethrum,spinosad,andneemisallowed.Forthemostpart,vegetablescanbegrownforhomeconsumptionwithouttheuseofthechemicalinsecticides.Thismay,however,requiremoreworkthanifinsecticideswereused.

GENERAL GARDEN PESTS

White Grubs Severalspeciesofwhitegrubs feedon rootsorotherundergroundpartsofmost vegetables.Damagegenerallyconsists of root pruning, surface scars, or round gouges.Grubsaremostlyaproblem ingardens thatweresod thepreviousyear.Gardenswithgrassyweedsareattractivetobeetleswhentheylayeggs.Assoilispreparedforplantinginthespring,itshouldbecheckedforthepresenceofgrubs.

Christine

Brian

Whitegrubs

Wireworms Wirewormscan feedon seedsandseedlingsof corn,beans,andpeas,causingwiltingand/ordeathoftheyoungplant.Wirewormsfeedontheedibleportionsofpotato,sweetpotato, radish, carrot, rutabaga, and turnips. The roots ofcabbage,cucumber, tomato,onion,watermelon,andothercropsarealsoattacked,reducingvigororkillingtheplants.Despitethelonglistofhostplants,wirewormsarerarelyaproblemingardens.Wirewormsaremore likely to infestagardenifitweresodlastyearorhadlotsofgrassyweedspresent.

Obermeyer

J.

WirewormCutworms Cutwormsfeedonmostofthevegetablesgrowninthehomegarden.Themostcommondamageisyoungplantscutoffatthesoilsurface.Somecutwormsmayalsoclimbtheplantandfeedonfoliageandfruit.Damagecanbereducedbykeepinggardensfreeofweedsbeforeandaftervegetablesareplanted.Baitformulationsofsomeinsecticidescanalsoprovidecontrol.

University

Purdue

Obermeyer

J.

Variegatedcutworm Blackcutworm

Japanese Beetle InsomepartsofIndiana,theJapanesebeetleisthemostseriousinsectproblemthatmanyhomeownershavetocontendwith. Japanese beetles can be present in extremely highnumbers,arevoraciousfeedersonawidevarietyofplants,

Christine

Brian

Japanesebeetle

5 Managing Insects in the Home Vegetable Garden — E-21-W

andareverymobile,allowingthemtoconstantlyreinvadeatreatedyardorgarden.AlthoughJapanesebeetletrapscatchalargenumberofbeetles,theyarenotrecommendedforusebecausetheytendtoattractmorebeetlesthantheycatch.Unfortunately, theonlyway tosuccessfullyprotectgardenplantsthatarebeingattackedbyJapanesebeetlesiswithinsecticides.Neemcanbeaneffectiverepellent ifmultipleapplicationsarebegunwhenbeetlesfirstappear.

Tarnished Plant Bug Tarnishedplantbugsfeedwiththeirsuckingmouthpartsonbeet,chard,celery,beans,potato,cabbage,cauliflower,turnip, salsify, and cucumber. They suck plant juices andmay inject toxicsaliva into theplant.Leavesmaybecomedeformed,stemsandpetiolesmaybescarredanddiscolored,orthebudsanddevelopingfruitmaybedwarfedandpitted.Tarnishedplantbugsbecomeactiveearlyintheseasonandcanmigratetofindpreferredhostplants.

J.Obermeyer

J.Obermeyer

Tarnishedplantbugadultandnymph

Blister Beetles Adultblisterbeetlesfeedravenouslyontheleavesofmanyvegetables.Thebeetlescanbepickedoffofplantsbyhand,buttheycontainanoilthatcanblistertheskinifaccidentallycrushed.Thelarvaeofblisterbeetlesarebeneficial,burrowingthroughthesoilandfeedingongrasshoppereggs.

BrianChristine

Marginedblisterbeetle

Aphids Aphidsaresoft-bodiedinsectsthatfeedwiththeirsuckingmouthpartsontheleavesofmanygardenvegetables.Theyaremostcommonlyfoundinlargegroupsorcoloniesontheundersideofleaves.Aphidfeedingreducesthevigoroftheplantandmaycausetheleavestocurldownward.Aphidsaremostoftenkeptundercontrolbymanyofthenaturalenemies

thatfeedonthem.Theuseofinsecticidessuchascarbaryl(Sevin) tocontrolother insectswillsometimesresult inanoutbreakofaphids,becausethenaturalenemiesarekilledbytheinsecticide.

Univ.W

isconsin

C.W

elty

Greenpeachaphid Turnipaphids

Twospotted Spider Mite Althoughmitesarenotinsects,beingmorecloselyrelatedtospiders,theyarevegetablepeststhatremoveplantjuicesfromtheleavesofbeans,corn,tomato,eggplant,etc.Theleavesbecomebronzedoryellowed,andthefoliagetakesonageneralwiltedappearance.Thesymptomsofmitedamagemaybecausedbyotherfactors,sobesuretolookformiteswithahandlenstoconfirmyourdiagnosis.Mitesaremoreofaprobleminhot,dryweather.Heavyrainsmayhelptocontrolmites.Sprayingplantswithagardenhosecanremovesomeofthemitesfromtheplants.

J.Obermeyer

W.C

ranshaw

Twospottedspidermiteanddamageoneggplant

Slugs Slugsarenotinsects,buttheyarepestsofvegetablesthatmayskeletonizeorshredleavesofmanygardenvegetablesormaydefoliatetheentireplant.Slugsaremoreofaproblemincool,wetweather.Severaldaysofwarmsunnyweatherusuallywill reduce theproblem.Piepansbaitedwithbeerburiedatgroundlevelwilltrapmanyslugs.Chemicalcontrolsarealsoavailable.

BrianChristine

Slugoncorn

6Managing Insects in the Home Vegetable Garden — E-21-W

MANAGING INSECTS ON SPECIFIC CROPS

Asparagus The asparagus beetle and the spotted asparagus beetlearebothfoundonasparagus,butonlytheasparagusbeetleisaseriouspest.Adultasparagusbeetlesare1/4inchlong,blue-black,withcreamyyellowspotswithredborderson thewings.Adultspottedasparagusbeetlesareslightlylarger,arereddish-orange,andhaveblackantennae,eyes,andundersides.Eachwingcoverhassixdistinctblackspots.Thesoft-bodiedlarvaeoftheasparagusbeetlereach3/8inchlongandaregraywithblackheads.Adultasparagusbeetlesattackthetenderbudsnearasparagustipsassoonastheshootspushabovethesoilinthespring.Theadultsalsofeedonthefoliage.Larvaeoftheasparagusbeetlefeedonthestemsandleaves,butthelarvaeofthespottedasparagusbeetlefeedonlyontheberries. Destroyingcropresiduefromthepreviousyeareliminatesoverwinteringsitesfortheadults.Hand-pickingadultscanalsobeuseful.Chemicalcontrolisusuallyquiteeffectiveandmaybejustifiedifthereareseveralbeetlesorlarvaepercrown,orifplantsarelosingtheirleaves.

MichiganStateUniv.

MichiganStateUniv.

Asparagusbeetleadultandlarva

MichiganStateUniv.

Spottedasparagusbeetle

Beans Green,wax,broad,andlimabeansgrowninthevegetablegardenareallattackedbyseveralinsects,butthedamageoftencanbetolerated.Thefirstinsectthatwillattackbeansistheseedcorn maggot.Theadultformisaflythatisslightlysmaller thanahouse fly.Thedamaging form is the larva,whichisawhite,leglessmaggotthatburrowsintoseedsandseedlings,causingpoorseedgerminationandemergence,and/or stemswithout leaves.Damage can be reduced byplantingseedsshallowandwhensoiltemperaturesarewarm

(760°F),sothattheplantswillnotstayintheseedstagelong.Usinginsecticidetreatedseedsoroverseedingwillalsohelp.Earlyplantinganduseofmanureforfertilizerwill increaseproblems.

J.Obermeyer

Seedcornmaggotingreenbeanstem

Potato leafhopper isfrequentlyapestonbeans.Adultsareabout1/8 inch long,brightgreen,andwedge-shaped.Bothadultsandnymphsfeedbysuckingplantjuices.Toxinsintheleafhopper’ssalivacauseplantstostuntandleavestoyellowandturnbrown,aconditioncalled“hopperburn.”Leafhoppersoftenwillmoveoutofalfalfa intoothercropswhenalfalfaiscut.Leafhoppersshouldbecontrolledbeforehopperburnsymptomsappear.

J.Obermeyer

J.Obermeyer

J.Obermeyer

Potatoleafhopperadult,nymphs,anddamage

Flea beetlesmaychewsmallholesinbeanleaves.Thisdamagewillusuallybeworseinweedygardens.Thedamageis usually only important on seedling plants. Carbaryl willprovideadequatecontrolifneeded.

PurdueUniversity

Red-headedfleabeetleandcornfleabeetle

7 Managing Insects in the Home Vegetable Garden — E-21-W

Mexican bean beetlescanbeapestofbeansinsouthernandcentral Indiana.Theadultbeetle is roundandcoppercoloredwith16blackspotsonitsback.Itisabout5/16inchlongand1/4inchwide.Itiscloselyrelatedtothebeneficialladybeetles.Mexicanbeanbeetleslayclustersofoval,yelloweggsontheundersideofbeanleaves.Thelarvaeareoval,yellow,andcoveredwithbranchedspines.Bothadultsandlarvaefeedonleaves,pods,andstems.LaterplantingwillreducetheamountofMexicanbeanbeetledamage.Becausetheinsectsareslowmovingandhighlyvisible,handpickingcanbeasuitablecontrolmethod.Severalinsecticidesalsowillprovidegoodcontrol.

PurdueUniversity

Mexicanbeanbeetleadult,larva,pupa,anddamage

Bean leaf beetlesmayfeedonleavesandpodsinallareasofthestate.Adultbeetlesmayormaynothavespotsandmaycomeinseveralcolors,buttheywillalwayshaveablacktrianglebehindthehead.Beanscanusuallytolerateaconsiderableamountofleaffeedingwithnoeffectonyield.Beetlespresentwhenpodsareformingshouldprobablybecontrolled.

J.Obermeyer

PurdueUniversity

Beanleafbeetlesandpoddamage

Cruciferous Crops (Cabbage, broccoli, cauliflower, Brussels sprouts, radish, turnip) Mostcrucifersareattackedbythesamecomplexofinsectpests.Radishesaresucharapidlygrowingcrop(maturingin

about28days)thattheyarenotusuallyaffectedbyinsects,otherthanpossiblyafewcabbagemaggotsfeedingontheroots.Turnipsgrownfortherootsarealsounlikelytohaveanyseriousinsectproblems,otherthanrootmaggots. The first insect problem that will occur on crucifers isthecabbage maggot.Theadultfly,whichisslightlysmallerthanahousefly,emergesinlateAprilorearlyMay.Theylaywhiteeggsatthebasesofnewlysetplants.Theeggshatchintoleglessmaggotsthatmigrateandtunnelintotheroots.Theycausetheplantstoappearsickly,offcolor,orstunted,andmaycausethemtodie.Injuryisusuallymoresevereincool,wetconditions.Forthehomegardener,chemicalcontrolisusuallynoteffective.Anothergoodideaistoplantafewmoreplantsthanneeded,incaseafewarelosttocabbagemaggots.Fliesareattractedtodecayingorganicmatter,soexcessiveuseofmanureshouldbeavoided.

C.E

astman

Cabbagemaggotdamage

Flea beetles are almost always a pest of crucifers.Carbarylwill usuallyprovidesuitablecontrol.Aphidsmayattackallthecrucifers,aswell.Thenumberofaphidsmaybereducedbydestroyingcropresiduewhenthegrowingseasonhasendedandbyencouragingnaturalenemiessuchasladybeetles.Naturalenemiescanbeconservedifuseofchemicalinsecticidesiskepttoaminimum.

Palestripedfleabeetle

PurdueUniversity

R.K.C

hapm

an

Cabbageaphidsonleaf

C.E

astman

Cabbageaphiddamage

8Managing Insects in the Home Vegetable Garden — E-21-W

Asmostgardenersknow,themostseriousinsectproblemoncrucifersisthecaterpillars.Thereareactuallythreedifferentspecies of caterpillars that are serious pests of crucifers.Diamondback moth larvaearesmall(1/2inch),cigar-shapedgreencaterpillars thatwriggle rapidlywhen touched.Theypupateinlittlesilkencasesgluedtotheundersidesofleaves.Eachlarvadoesnotdoagreatdealofdamage,buttheycanoccurinextremelyhighnumbers.

caterpillars and treated when necessary, or Bt should beappliedonaweeklybasis.Thepyrethroid insecticidesarealsoquiteeffective.

Solanaceous Crops (Tomatoes, potatoes, peppers, eggplant) Solanaceous crops are attacked by a wide variety ofinsects.Severalofthesepestscanbequitesevereanddifficulttocontrol,asisindicatedinTable1.Thesecropsareoftendifficulttogrowsuccessfullywithoutusinginsecticides. ThemostnotoriousofallthepestsofsolanaceouscropsistheColorado potato beetle.Thisinsectfeedsonallfourtypesofsolanaceouscropsinboththelarvalandadultstages.Theadult isayellowbeetleabout1/2 inchlongwitheachwingcoverbearingfiveblackstripes.The larva is reddishwithablackheadandlegsand2rowsofblackspotsalongeachside.Overwinteringadultsfrequentlybeginfeedingonpotatofoliageassoonasitisaboveground.Bothadultsandlarvaefeedonalltheleaftissueexceptforthemainleafveinandstems.Therearetwogenerationsperyear.Theinstarguideonpage9willhelp thehomegardenerknowwhichinstarsarepresent.The larger instarswill consumemuchmorefoliageeachdayandarealsomuchmoredifficulttokillwithinsecticides.Therefore,itisimportanttomakeinsecticideapplicationswhenthelarvaearesmall(1stor2ndinstars).Inmanyareas,Coloradopotatobeetlesareresistanttomostinsecticidesavailabletohomeowners. Bacillus thuringiensisinsecticidesspecificallyforpotatobeetlescanbeeffectiveifappliedwhenlarvaearesmall(1stor2ndinstar).Otheravailablealternativetoinsecticidesinclude

J.W

yman

DiamondbackmothlarvaanddamageR.Foster

Theimported cabbagewormisthelarvalstageoftheverycommonwhitecabbagebutterflywithblackspotsonthewingtips.Thecaterpillarsarevelvety-greenandreachover1inchinlength.

Importedcabbagewormadultandlarva

W.C

ranshaw

W.C

ranshaw

Thecabbage looperdoesnotoverwinterinIndiana,butflieshereeachJune.Thelarvaearelightgreen,and,whentheycrawl,theymakeacharacteristicloopinthemiddleoftheirbody.Thesecondgeneration,whichoccursinAugustandSeptember,isthemostserious. Allthesecaterpillarsfeedontheleavesandcanreducetheplantgrowth.Themostseriousdamageistotheportionsofplantsthataretobeconsumed.Fortunately,goodcontrolcanbeachievedwithvariousformulationsofBacillus thuringiensis.Thismaterialisverysafeandwillnotharmbeneficialinsects.It ismuchmore effective on the young larvae.Therefore,plantsshouldbeinspectedonceortwiceperweekforyoung

Cabbagelooperanddamage

J.Obermeyer

S.M

ahr

W.C

ranshaw

W.C

ranshaw

Coloradopotatobeetleeggsandlarva

W.C

ranshaw Coloradopotatobeetleadult

Coloradopotatobeetledamage

W.C

ranshaw

9 Managing Insects in the Home Vegetable Garden — E-21-W

2 3 41

InstarGuideColoradoPotatoBeetle

Determineintowhichcirclethelarvafitsmostcompletelywithoutoverlappingtheborders.Thenumbercorrespondingtothatcircleistheinstarforthatlarva.

handpickingadultsofftheplantsanddestroyingthembeforetheybegintolaytheirorange-redeggsontheundersidesoftheleaves.Damagecanalsobereducedbyapplyinga4-6inchlayerofstrawmulchonbothsidesofthepotatorowrightafterhilling. Flea beetleswillattackallofthesolanaceouscrops,butcanbeparticularlydamagingtoeggplant.Fleabeetlesaresmall,hard-shelledinsects,sonamedbecausetheirenlargedhind legs allow them to jump like fleas from plants whendisturbed.Theirdamageisunusualinappearance.Theyfeedbychewingasmallholeinaleaf,movingashortdistance,thenchewinganotherhole,andsoon.Mosthealthyplantscantolerateaconsiderableamountoffleabeetledamage,andcontrolisobtainedeasilywithanumberofcommongardeninsecticides.RefertoExtensionpublicationE-74,Flea Beetles,foradditionalinformation.

Univ.W

isconsin

Fleabeetlesanddamage

Univ.W

isconsin

Thepotato leafhopperdescribed in thebeansectionisalsoapestofpotato,doingdamagesimilartothatdonetobeans.Leafhoppers cancausesubstantial yield lossatrelativelylowdensities.Treatmentisjustifiedifthereismorethanonenymphpertenleaves.Severalspeciesofaphidswillattacksolanaceouscrops.Fortunately,potatoesandtomatoescantolerateaconsiderableamountof feedingwithoutanyeffect on yield. However, aphids feeding on peppers cantransmitseveralviraldiseasesthatarequitedetrimentaltopepperplants.Peppers,therefore,shouldbekeptrelativelyfreeofaphids.

MichiganStateUniv.

Univ.W

isconsin

Potatoleafhoppernymphs,adult,anddamage

Severalcaterpillarsmaybefoundfeedingontomatoes.Thetobacco hornwormisaverylargegreenishcaterpillar(upto4inches)withaspineontherearendandwhitestripesonthesides.Larvaefeedonboththeleavesandthefruit,and,becauseoftheirlargesize,onelarvacandoaconsiderableamountofdamage.Hornwormsusuallydonotoccurinlargenumbers,sohandpickingisagoodmethodofcontrol.Theyareharmlesstohumans.

W.C

ranshaw

Tobaccohornworm

The tomato fruitworm (also thecorn earworm) is alate-seasonpest(August-September)thatboresintothefruit.Thelarvaevaryconsiderablyincolorfromlightgreentotan,brown,pink,maroon,ornearlyblack,withlightanddarkstripesrunninglengthwiseonthebody.Theyreachalengthofabout11/2inches.Theymaybecontrolledwithinsecticides,butusuallythedamagecanbetoleratedandthedamagedfruitsimplydiscarded.

G.B

rust

G.B

rust

Tomatofruitwormanddamage

10Managing Insects in the Home Vegetable Garden — E-21-W

Vine Crops (Cucumbers, melons, pumpkins, squash) Seedcorn maggots are closely related to cabbagemaggotsandwillattackallthevinecrops.Damageismoreserious if thecropsareplanted intoheavilymanuredsoil.Damageisalsomoresevereincoolweather.Plantswillgrowmorevigorouslyiftheyareplantedaslateaspossible.Also,plantingafewextraseedsperhillwillreducetheeffectofanyseedcornmaggotinjury.

G.B

rust

G.B

rust

Seedcornmaggotanddamage

Probably themost serious insect pests of vine crops,especiallycucumbersandcantaloupes,arethespottedandstriped cucumber beetles.Thespottedcucumberbeetleisgreenishyellowandhas12blackspotsonthewingcover.Thestripedcucumberisyellowwiththreeblacklinesrunningthelengthofthebody.Thelegsandundersidesarealsoblack.Thebeetlesfeedonstemsandleaves,butthemostimportantdamage they do is to transmit a bacterium that causes adiseasecalledbacterialwiltofcucurbits.Thediseaseplugsup the liquid-conducting tubeswithin theplantand resultsinthesudden,severe,andpermanentwiltofasingleplantrunnerortheentireplant. The onlyway to prevent the disease is to control thebeetles.Whentheplantsaresmall, theycanbeprotectedfrombeetlefeedingbycoveringtheplantswithasmallmeshmaterialsuchasabridalveilsupportedonastickwithdirtsealingtheedgesontheground.Ofcourse,whentheplantsstarttobloom,theclothmustberemovedtoallowbeestopollinatetheplants.Theothercontroloptionistoprotecttheplantswithaninsecticidewhenthebeetlesarepresent.

J.Obermeyer

R.Latin

A.York

Stripedcucumberbeetle Spottedcucumberbeetle

Earlysymptomsofbacterialwiltofcucurbits

Melon aphidsoccasionallybuildupontheundersidesoftheleaves,causingtheplantstobestuntedortowilt.Aphidsaremoreofaprobleminhot,dryweather.Naturalenemiesusuallywillkeepaphidsundercontrol,butmalathionorsoapwillprovideadequatecontrol.Spider mitesareanon-insectarthropodthatsuckplantjuicesfrommanytypesofplants.Theyarealsomoreofaprobleminhot,dryweather.Sprayingcarbaryl tocontrolotherpestswilloftenincreasemiteandaphidproblemsbykillingtheirnaturalenemies.

G.B

rust

G.B

rust

Melonaphidanddamagetowatermelon

Pumpkinsandsquasharemostseriouslyattackedbysquash bugs.Squashbugadultsarebrownish-blackbugsthatreachabout5/8inchinlength.Thenymphsarevarioussizesandarewhitishwithblacklegs.Bothnymphsandadultssucksapfromleavesandunripefruit,causingplantstowiltanddie,andfruittocollapse.Thenymphsoftenwillclustertogetherinlargegroups.Destroyingcropresiduewillreducetheproblemsyouwillhavenextyear.

J.O

bermeyer

J.Obermeyer

Squashbugeggs,nymphs,andadult

J.Obermeyer

11 Managing Insects in the Home Vegetable Garden — E-21-W

Thesquash vine borerisasporadicpestofsquashandpumpkins,butcanbeseriousattimes.Thedamageisoftenfirstapparentasthesuddenwiltingofanotherwisehealthyvineorplant.Massesofgreenish-brownfrasswillbepushedoutoftheentranceholeatthebaseoftheplant.Awhitegrub-likecaterpillarcausesthedamagebyboringintothevine.Theadultisaclearwingmoththatlookslikeawaspandisactiveinthedaytime.Theonlyin-seasoncontrolmethodistousetwoinsecticidesprays,7daysapart,beginningwhenthevinesstarttorun.Destroyingcropresiduewillalsoreducesquashvineborerproblemsnextyear.

PurdueUniversity

C.W

elty

R.Foster

Squashvineborerlarva,adult,anddamage

Sweet Corn TheEuropean corn borerattacksboththefoliageandtheearsofsweetcorn.Thelarvahasapalewhitebodywithseveralbrownorblackspotsandablackhead.Afewholesintheleavesofyoungcornplantsisnotacauseforconcern.Asubstantialamountofdamagetowhorlstagesweetcorncanbetoleratedwithoutanyeffectonyield.Europeancornborerscanbecontrolledbytreatingwithaninsecticidewhenthetasselsbegintoemerge.Oneortwoapplicationsspacedfivedaysapartwillusuallyprovideadequatecontrol.Thecorn earwormisthesameinsectthatwecallthetomatofruitwormwhenitoccursontomatoes.Itsdamageismostlylimitedtotheears,usuallytheeartips.Controlofcornearwormscanbeachievedbysprayingthegreensilksanddevelopingearswithpyrethroidinsecticides.Bacillus thuringiensis insecticidesshouldnot beused for cornearworms; theydonotwork.Mostofthedamageisusuallyconfinedtothetipsoftheearsandcanbesimplycutoff,eliminatingmuchoftheneedforinsecticides.

Europeancornboreranddamage

J.Obermeyer

Cornearworm

J.Obermeyer

BENEFICIAL ARTHROPODS Onlyaverysmallpercentageoftheinsectsthatoccurin Indianaarepests,andonlya fewof thesearepestsofvegetables. Most insects are so innocuous that they areseldomnoticed.Manyprovidefoodforlargeranimals,helpbreakdowndecayingplantsandanimals,etc. Otherinsectsprovidedirectbenefitforgardeners.Anumberofinsectsandotherarthropodsarepredators;thatis,theyeatotherinsectandmitepests.Predatorsincludespiders,adultandimmatureladybeetles,adultandimmaturelacewings,preyingmantids,somestinkbugs,andgroundbeetles.Otherinsectsactasparasitesonpestinsects.Theseincludeanumberofspeciesofwaspsandflies,whichlayeggsinoronthehostinsect.Thus,itisimportanttoconserveasmanypredatorsandparasitesaspossible.Often theywill control thepestspecieswellenoughthatadditionalcontrolisnotnecessary.Agoodmethodforconservingbeneficialinsectsistosprayinsecticidesonlywhennecessaryandtochooseinsecticidesthatareleasttoxictothebeneficialinsectswheneverpossible. Oneofthemostnotablebeneficialinsectsisthehoneybee.

12Managing Insects in the Home Vegetable Garden — E-21-W

Besidesprovidinghoney,beesserveaspollinatorsformanyofourvegetableandfruitcrops.Withoutthesepollinators,manycropswouldneverproducefruit.Insecticidesthataretoxictobeesshouldneverbeappliedwhenplantsareinbloom.

Ladybeetleadultandlarva

J.Obermeyer

Brianchristine

J.Obermeyer

W.C

ranshaw

Predaceousstinkbug Groundbeetle

BrianChristine

BrianChristine

Lacewinglarva Greenlacewingadult

J.Obermeyer

Parasitizedaphidmummy

J.Obermeyer

Jumpingspider

J.Obermeyer

Parasitizedhornworm

J.Obermeyer

Honeybee

READANDFOLLOWALLLABELINSTRUCTIONS.THISINCLUDESDIRECTIONSFORUSE,PRECAUTIONARYSTATEMENTS(HAZARDSTOHUMANS,DOMESTICANIMALS,ANDENDANGEREDSPECIES),ENVIRONMENTALHAZARDS,RATESOFAPPLICATION,NUMBEROFAPPLICATIONS,REENTRYINTERVALS,HARVESTRESTRICTIONS,STORAGEANDDISPOSAL,ANDANYSPECIFICWARNINGSAND/ORPRECAUTIONSFORSAFEHANDLINGOFTHEPESTICIDE.

Revised 5/2010

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