insects in grain

8/12/2019 Insects in Grain

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~ t B Stored raint ; ~ . . ; : . Insects .oq = - .- , -ft . - C: , _


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ABSTRACT~ . P J)' p...1> ta . . . . . . . . . . . . of 11M: . .>I


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ONTENTS ge

Flour moths Indian meal moth Mediterranean flour moth Meal moth

Grain weevils r n ry weevil Rice weevil Maize weevil Broadnosed grain weevil Coffee bean weevil Grain borers

Lesser grain borer Larger grain borer

Grain and flour beetles Cadelle Sawtoothed grain beetle Merchant grain beetle Squarenecked grain beetle Foreign grain beetle Mexican grain beetle Siamese grain beetle Flat grain beetle Rusty grain beetle Confused flour beetle Red flour beetle American black flour beetle Longheaded flour beetle Slenderhorned flour beetle Smalleyed flour beetle Depressed flour beetle Broadhorned flour beetle :Larger black flour beetle

.. .... < oO t . ,

ntroduction 1112334668Grain moths 9Angoumois grain moth 9Pink scavenger caterpillar 1European grain moth 12Rice moth 12

14141516191922121222222232424262728292929293


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geEggs of flour and grain insects 31Mealworms 32

Yellow mealworm . 32Dark mealworm 34Lesser mealworm 34Black fungus beetle 34Redhorned grain beetle 35Dermestid beetles 37

Black carpet beetle 37Trogoderma beetles 37Spider beetles 40

Hairy spider beetle 40Whitemarked spider beetle 40Brown spider beetle 41Other spider beetles 41Miscellaneous beetles . . 42Twobanded fungus beetle 42Hairy fungus beetle 42

Corn sap beetle . 43Cigarette beetle . 44Drugstore beetle 45Catorama beetles 45Murmidius beetle 46Booklice or psocids 46Silverfish 47Cockroaches 48Flour or grain mites 50Parasites of grain pests 52

How grain becomes infested. . . . 55How to prevent or reduce primary infestation 56

Prepared by theAarlcultara. Relearch ServiceUalted tat Departmeat 1AarlcultareThis handbook supersedes and enlarges Farmers Bulletin 1260, Stored-Grain Pests.

Washington, D.C. IssuedFebuary 1978Revised and approved fex printing January 1986


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2 AGRICULTURF. llANDROOK NO. U.S. DF.PT, ~ lIGHICULTLlIEch.


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STORED GRAIN INSECTS 3abou t three thirty-seconds of an inchin length. It varies from reddishbrown to nearly black and is usuallymarked on the back with four lightreddish or yellowish spots fig. 1BThe rice weevil closely resembles theg ra na ry weevil in form but differs incolor and markings, and it has fullydeveloped wings beneath the wingcovers. The thorax is densely pittedwith somewhat irregularly shapedpunctures except for a smoothnarrow s tr ip extending down themiddle of the upper dorsal) side.

This weevil has been k nown sinceearly times. It is found in all parts ofthe world where grain is used and isone of the worst pests in stored grain.This insect is particularly abundant inwa rm countries, where it breeds c on t inuously and rapidly destroys allunprotected grain.

The adult rice weevils live, on anaverage 4 to 5 months and eachfemale lays 300 to 400 eggs duringthis period. The early life stages arealm ost identical in habit and appearance to those of the granary weevil.During hot weather, the egg, larval,and pupal stages may be passed in asfew as 26 days. This period ofcourse, is greatly prolonged duringcool or cold weather.

Maize WeevilThe maize weevil itop ilus

ze m ise Motschulsky, for a longtime referred to as the larger strain orrace of the rice weevil, is now recognized as a distinct species. Altho ugh

slightly larger up to one-eighth of aninch long, and darker than the riceweevil adult, the degree of variationwithin each species makes them difficult to tell apart fig. C). The thoraxof the maize weevil is densely anduniformly pitted with round punctures.

It is a common pest of a variety ofgrain crops and causes tremendouslosses to corn in the South reducingthe kernels to dry powder and hulls fig. 2). The adults fly from thegranaries to the fields, where theystart infestations that may c on tin ueafter harvest and may be especiallydestructive in storage.

The life history and early lifestages are similar to those of the riceweevil fig. 3). The rate of developm ent is slightly slower; a m inim umof 30 days is required for passingthrough the egg, larval, and pupalstages.

roadnosed rain WeevilThe broadnosed gra in weevil, ulophilus oryz e Gyllenhal), is a

small dark brown snout beetleslightly less than one-eighth of aninch long. In form and color, itresembles the grana ry weevil somewhat but differs from it and othergrain-infesting weevils by having ashorter, broader snout fig. 4C).

The weevil is occasionally found inGeorgia and South Carolina and iswidespread in Florida, where it is aserious pest of stored grains, but it isnot found in northern grains. It isunable to breed in dry, hard unin-


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AGRI CULTURE HANDBOOK NO. 500, U.S. DEPT. OF AGRICULTURE

J05QFigure 2. near of corn badly damaged bymaize \;15. The car was hit against atable to jar loose a dry powdery substance.or farinaceous material. to reveal the greatamount of damage done

jured grain, but it docs a tt ack so ft ordamaged grain o r grain th at has beenattacked by o the r grai n insects. t is as t ro ng fl ier. a nd . li ke th e mai zeweev il. flies to t he cornf ields a ndinfests the grain before it becomesfully ha rdened.

The adu lt weevils normally livea bout 5 mon th s. and . du ring thi st im e. ea c h female lays 200 to 300small white eggs. usually in brokenportions of the gra in. In a few day s.the eggs hatch. and th e small. white.legless grubs feed on the softer portions of the grain until fully gro wnfig. 4A They the n tr ansform intowhite pu pae fig . 48) an d . in a fewday s . tra nsfo rm into adult weevilswhich cu t their way ou t of the grain.In summer. the period from egg toadu lt is about I month .

Coffee Bean WeevilThe coffee bean weevil r ecerus

s u l tus De Gce rj .s is a veryac tiv e. robu s t . d a rk- b ro w n beetletwo-six teen ths to three-sixteenths ofan inch long. t is covered with amottled ligh t- and dar k brown pubescence. Th is insect may be easily reeognized from figure 5.

T his weevil is found in manycountries and is extremely abundantin the So ut hern S tate s. where itbreed s in dr ied fruit. co ffee berries.cornstalks. c and the seed ands ee d pod s o f an al m os t endlessvar iety of p lants. The co ffee beanweevil is a strong flier and is fre-quently seen in the co rn fields of th e

Coleoptera. Ar uhn hidac.


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rl'OR EO GRAIN INs TS

A B cf_ _ _ _ _ _


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6 AGRICULTURE HANDBOOK NO. 500, U.S. DEPT. OF AGRICULTURESouth on exposed and damaged ears.t lays eggs in the soft kernels of cornand continues to breed after the cornhas been harves ted a nd placed insto rage. This insect does not causemuch damage to co rn in storage.since the cornbecomes too hard to beattractive. It may. however. be veryabundant locally in corn in Floridaduring the first 3 months of storage.This weevil reportedly caus ed to taldestruction of a sack of kafir seeds inHonolulu . Over th e coun try , th ecoffee bean weevil is a minor grainpest.

W -517Figure 5.- Coffee bean weevil adult. about

three-sixteenths of an inch long.

R IN OR RSThree species of grain borers arc

esta blished in the United Sta tes. Thelesser grain borer is widespread in thegrain centers of this country and is as rious pest of stor grain . Thelarge r grain borer and the bamboopowderpost beetle a re confined to theSouthern States and are not of commercial importance.

Lesser Grain orerh e le ss e r g rain b o r e r .h yzoperth dominic Fabr icius).

is one of the smallest beetles of thoseinjurious to gr n in this country. It isknown to many grain dealers as theAustralian wheat weevil because ofthe large supplies of infested wheatthat were imported from Australia

Coleoptera. Bost richidae.

during World War t is widespreadin the ulf States, and grai n samplesinfested with this beetle arc found ina ll la rge gra in cen te rs . The lessergrain borer is readily distinguishedfrom other grai n pests by its slendercylindrica l form and small size. ispolished dark brown or black. with asomewhat roughened surface. and isabout one-eighth of art inch long andone thirty-second of an inch wide fig. A The larval and pupal stagesare illustrated in figure 7. This grainborer belongs to a family of beetlesthat has the head tu rned down underthe thora x and tha t is armed withpowerful jaws used for cutting intowo od . O r igin all y nat ive t o t heTropics. the lesser grai n bore r hasspread through commerce to all part sof the world.


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6 AGRICULTURE HANDBOOK NO. 500, U.S. DEPT. OF AGRICULTURESouth on exposed and damaged ears.t lays eggs in the soft kernels of cornand continues to breed after the cornhas been harves ted a nd placed insto rage. This insect does not causemuch damage to co rn in storage.since the cornbecomes too hard to beattractive. It may. however. be veryabundant locally in corn in Floridaduring the first 3 months of storage.This weevil reportedly caus ed to taldestruction of a sack of kafir seeds inHonolulu . Over th e coun try , th ecoffee bean weevil is a minor grainpest.

W -517Figure 5.- Coffee bean weevil adult. about

three-sixteenths of an inch long.

R IN OR RSThree species of grain borers arc

esta blished in the United Sta tes. Thelesser grain borer is widespread in thegrain centers of this country and is as rious pest of stor grain . Thelarge r grain borer and the bamboopowderpost beetle a re confined to theSouthern States and are not of commercial importance.

Lesser Grain orerh e le ss e r g rain b o r e r .h yzoperth dominic Fabr icius).

is one of the smallest beetles of thoseinjurious to gr n in this country. It isknown to many grain dealers as theAustralian wheat weevil because ofthe large supplies of infested wheatthat were imported from Australia

Coleoptera. Bost richidae.

during World War t is widespreadin the ulf States, and grai n samplesinfested with this beetle arc found ina ll la rge gra in cen te rs . The lessergrain borer is readily distinguishedfrom other grai n pests by its slendercylindrica l form and small size. ispolished dark brown or black. with asomewhat roughened surface. and isabout one-eighth of art inch long andone thirty-second of an inch wide fig. A The larval and pupal stagesare illustrated in figure 7. This grainborer belongs to a family of beetlesthat has the head tu rned down underthe thora x and tha t is armed withpowerful jaws used for cutting intowo od . O r igin all y nat ive t o t heTropics. the lesser grai n bore r hasspread through commerce to all part sof the world.


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sroneu GItAIN INHA- TS 7

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8 AGRICULTURE HANDBOOK NO. 500 U.S. DEPT. OF AGR ICULTUREBoth the beetles and la rvae causeserious damage in warm climates by

tt cking a grea t va riety of grains.Figure 8 shows how dest ructive theycan be to wheat kernels. which. inth is case were literall y riddlcd by thcboring of the adults and their larvae.Th e damaged kernels a re always surrounded by powder from the chewedup gr in.Each female lays 300 to 500 eggsand deposits them singly or in clusters upon the loose grain. The eggshatch in a few days and the smallwh it i sh g ru s o r la rv ae . cra wlactively about the grain and feed onthe flour produced by th e bori ng beetles or bore directly into gra ins tha thave been slightly d maged . Th eycom ple te th e ir growth wit h in thegrain transform into white pupae.and in time. change into adult beelies. which cut thei r way out of thegrain. In summer the period fromegg to adult is about I month.

Larger Grain BorerTh e larger grai n borer Pros-

tep hanus { ru o s H o r n ). is asml l. da rk -b ro wn elong tecylindri cal beetle about one-sixth ofan inch long. It is very similar inappea nce to the lesser grain borerbut may be d istinguished from tha tinsect by its larger size and compara-tively smooth polished surface fig .

This tropi cal insect has limited di stribution in this country. It is occa-siona lly foun d infesting corn in theSou th and has been reported fromTexas Ca liforn ia. and th e District ofColumbia. Simi lr to the lesser grainbo rer in habits it belongs to a familyof beetles that is main ly des tructive totimber. Like the lesser grain borer. itha s p ro babl y acqu i red the gra infeeding habi t rather recently.Another member of the fam ily the mboo powderpost beetle inod

H: Jt Jfigure S. Whenl kernels thoroughly riddled and devoured hy bo ring and feeding of lesser grain

bo rer and its larva.


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STORED GRAIN INSECTS 9

c A

I D

ON-30M

Figure 9.-Larger grain borer: A adult; B larva; C, pupa; D antenna of adult.

erus nutus (Fabricius); occasionally infests stored grain in theUnited States. It has been reportedfrom Louisiana and Florida. In general appearance it resembles thelarger grain borer (fig. 6B .

R IN MOTHSThe term grain moth includes

only those moths capable ofdestroying sound, unbroken grainkernels. They are not as abundant asthe flour moths, which are principallypests in broken, damaged kernels ormilled products.ngoumols rain MothThe Angoumois grain moth, ito-trog cere lell (Olivier), is a smallbuff or yellowish-brown moth with awing expanse of about one-half inch.

Lepidoptera. Gelechiidae.

This is the moth most commonlyfound in infested grain in thiscountry, and it is not likely to be confused with any other grain moth. Itattacks all cereal grains, is found inall parts of the world, and is particularly injurious in the South where itattacks grain both in the field and instorage. In the North it survives thewinter mainly in the larval form inkernels of grain in storage or in scattered wheat n litter, straw piles, andbaled straw. The emerging moth fliesto the wheatfields in May anddeposits eggs upon the developinggrain.


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1 AGRICULTURE HANDBOOK NO. 500, U.S. DEPT . OF AGRI CULTUREUnder normal conditions. each

female lays an averag e of 40 eggs;alt ho ugh, under favo rable conditions.individual moths have been known tolay as many as 389 eggs. T he eggs.which a re white when first laid . sooncha nge to a reddish color. They arelaid on wheat heads, on the exposedtips of co rn ea rs in the field. or onsto red grain .

Upon hat ching, eac h larva crawlsto a kernel of grain a nd often spins asma ll entrance cocoon to assist it inbo ring into the hard kernel. Afte rentering the grain. it feeds on eitherthe endosperm or the germ until fullygrown. It then eats out a channe l tothe outside of the seed and makes aweakly fastened flap at the exit bycutting the shell one-half th reefourt hs o f the ci rcumference of acircle. Th e larva then spins a silkenco coo n and cha nges to a redd ishb rown pupa La ter. a s a moth , itpushes its way thr ough the flap , Theper iod fro m egg to adult may becompleted in 5 weeks. a lthoughdevelopment is usua lly slower.

Widesp read use of the combineha rvester ha s reduced wheat damageby th is moth to a minimum. However in the southern port ion of thecomme rcial corn growing area itpe riodica lly causes heavy losses tostored co rn . Figur e 10 sho ws an earof corn with the exte al evidence ofa heavy a tt a ck by the Angoumoisgrain mo th. F igure I I shows the successive stages in the development ofthi s insect in a kernel of wheat . fromegg to adult. Figure A shows thead ult mot h.

Pink Scavenger aterpillarThe pink scavenger caterp illar.

athrobrota riley Walsingharnj . isthe la rva . o r caterpillar. of a smallmo th. is pink, wit h a pale-brownhead and tho ra cic shie ld . and isabout five-sixteenths of an inch longwhen fu lly grown fig. 12C). Themoth which develop s from tbis larva

Lcpidopteru. Cosmop tcng iduc.

Figure . ar of corn showing heavy infestation by the Angoumois grain moth. Note that cer-

tain kernels have three emergence holes. and that many kernels have served as food for two lar-vae .


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STORED GR I N INSE TS

Female moth lays egg on grain kemal .The larva emerging from egg gnaws ahole no larger than a pin prick throughwhich it enters the kernel.

ernel cut showing entrancechannel. Larva feeds andgrows. enlarging cavit y.

11

N OUMOISR IN MOTHDEVELOPMENT IN WHEAT

The tull grown larva is aslong as kernel in which ithas eaten out a large cavi ty .

The pupa is the stagebetween larva andadult moth .

The moth leaveskernel by roundholeshown .

: oi3067f- gure l L Life cycle of the Angoumoi s grai n mot h on heat.


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12 AGR ICULTURE ~ I J I l O O K NO , MO, U.S . ner-r. OF ACKlcULTUR E

~ J 11. - (;, motn. 14 . ~ m ... J . . n . d ~ , p , . co ,,,,. d lo; .... , p . . . .


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STORED R IN INSECTS 13

:\ -3071Figure D .- Cut ea r of co rn showing charac

re ri snc feed ing and destruction by pinkscavenger cater pilla r larvae. La rvae eat fromone kern el to ano ther an d often sever kernels fro m cob. Larvae sometimes eat intoco b and t ransform into pupae there. Pupaea rc about one -third as long as the kernelshown.

expanse of about half an inch and ispale grayish brown or law ny (fig . 15).The la rva somewhat resembles that ofth e Ind ian meal moth . When fullygrown. the la rva is about half an inchlong and varies in color from whit e to

Figure l t. c European grain moth adult . Adult

has a wing expa nse of about one-ha lf of aninch.

.-0I:

Rs OnFigure IS.- Rice moth adu lt: t t dorsal view with wings spread ; ri ht side view with wings

folded to body. Adull has a wing spread of about one-half of an inch.


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14 AGHl CUl.T URE HANDBOOK NO. 500, U.S. DEPT. OF AGHICULTUREa dirty, slightly bluish gray with occasional tints of green fig. 16 .Damage by this pest, as with allmoth pest s, is done by the larvae,which a re rather gene ral feeders .They attack such materials as rice,cocoa, chocolate, dried fruit , biscuits,and seeds . The larva e produce adense webbing as they become fully

grown. When feeding upon grains,they spin dense silken tub es and webthe grain kern els into the walls of thetubes. Th e moth s live I to 2 weeks,and each female lays 100 to 200 eggs.n summe r the development periodfrom egg to adult is abo ut 6 weeks.Th e rice mo th has not as yet becomevery widely spread in th is country.

Figure 6 l-ull-gro n la rva of the rice moth about one- half of an inch long

FLOUR MOTHSAmong the I ur moth s a re some

of the co mmonest and most seriouspests of gra in products. They are designated as flour moths not becauset hey feed enti rely u pon fl ou r ormilled produ ct s, but because theyseldom attack sound kernels. Theseinsects prefer broken grains, grainsinjured by maj or grain pests. andmore especially milled cereal products such as 1I0ur. break fast foods.and meals . All thr ee 1I0ur moths arecommonly found in grain warehou ses, but the Indian meal mothand the meal moth are pro bably themost frequently reported. Thes e twomot hs may un der exceptionallyfavora ble co nditions become estab-

lished in whole grai n and other seedsand cause injury. especia lly by eatingout the germ.

Indian Meal MothThe Ind ian meal mot h. lodi

interpunctell Hub ner is a ratherhandsome moth with a wing expanseof nearly three -fourths of an inchfigs. 17 and ISA . t is easily distingui shed from othe r grain pests bythe peculiar markings of its forewings, which are redd ish brown witha co r luster on the outer tw -thi rds but whitish gray on the inneror body ends .

Each female moth lays 100 to 300


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14 AGHl CUl.T URE HANDBOOK NO. 500, U.S. DEPT. OF AGHICULTUREa dirty, slightly bluish gray with occasional tints of green fig. 16 .Damage by this pest, as with allmoth pest s, is done by the larvae,which a re rather gene ral feeders .They attack such materials as rice,cocoa, chocolate, dried fruit , biscuits,and seeds . The larva e produce adense webbing as they become fully

grown. When feeding upon grains,they spin dense silken tub es and webthe grain kern els into the walls of thetubes. Th e moth s live I to 2 weeks,and each female lays 100 to 200 eggs.n summe r the development periodfrom egg to adult is abo ut 6 weeks.Th e rice mo th has not as yet becomevery widely spread in th is country.

Figure 6 l-ull-gro n la rva of the rice moth about one- half of an inch long

FLOUR MOTHSAmong the I ur moth s a re some

of the co mmonest and most seriouspests of gra in products. They are designated as flour moths not becauset hey feed enti rely u pon fl ou r ormilled produ ct s, but because theyseldom attack sound kernels. Theseinsects prefer broken grains, grainsinjured by maj or grain pests. andmore especially milled cereal products such as 1I0ur. break fast foods.and meals . All thr ee 1I0ur moths arecommonly found in grain warehou ses, but the Indian meal mothand the meal moth are pro bably themost frequently reported. Thes e twomot hs may un der exceptionallyfavora ble co nditions become estab-

lished in whole grai n and other seedsand cause injury. especia lly by eatingout the germ.

Indian Meal MothThe Ind ian meal mot h. lodi

interpunctell Hub ner is a ratherhandsome moth with a wing expanseof nearly three -fourths of an inchfigs. 17 and ISA . t is easily distingui shed from othe r grain pests bythe peculiar markings of its forewings, which are redd ish brown witha co r luster on the outer tw -thi rds but whitish gray on the inneror body ends .

Each female moth lays 100 to 300


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HlUIl F.D GIIAIS INllECTS

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opt. . . in,i)' Of in , roup.. on food.....1. . . 1 With. . . . r... dIIy.. M Whold .IKI .mall .h ,I,' , . t . orC.I.fp, II , .m . f . Th. . . Ill ......te.d up on If .in . , f.in pfodu


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1 6 AGRICULTURE HANDBOOK NO. 500, U.S. DEPT . OF AGRICULTURE

Figure 19. Ear of co m with characteristicloose webbing left by larvae of ndi n mealmoth. This moth rarely attac ks sound grainbut often attacks grain already i ured byother grain pests. as shown here. Webbingdevelops o nly when grains are not mo vedfor some time

pale leaden g ray with tran sve rse,wavy. black markings fig. 20A 8

T hi s flou r moth is a nativ e ofurope . was first found in theUnited States in California in 1892.Since then. it has become widespreadover the country and for many year swas considered the most tro ublesomepest of flour mills. Th e larva spinssilken thread wherever it goes andwebs and mats together particles offoo d on whi ch it is feeding . Thema tted flour sometimes dogs the

machinery in flour mills and causesmilling operators to stop. In millsthat have an annual fumigation. thi sinsect is no longer a major problem.Although it pre fers flour and meal,the Med iterranean flour moth attacksgra in . b ran . ce rea l p roduct s. andmany other foodstuffs.

The female moth lays small whiteeggs in accumulations of flour . meal,or waste grain. With in a few days. asmall larva emerges from each eggfi g. 20C . When fu lly grown , thelarva is about half an inch long and iswhitish or pinkish, with a few smallblack spots on the body. The fullgrown larva spins a silken cocoon. inwhich the insect transforms into aredd ish-brown pupa fig. 20D Later.the adul t moth emerges from thepu pa . uring wa rm weather, theMediterranean flour moth requ ires 8to 9 weeks to pass through the egg,larval. and pupal stages.

Three other insect species occasionally infest grai n or cereal product s. T hey a re th e almond moth ,Cadra cautella Walker , the tobaccomoth , Ephesti a elu t lla Hubner,and the ra isin moth, Cadra ig ulilellaGregson . Of the three, the almondmoth is the most troublesome pestfig. 18C . is commonly found inseed stores and is a serious pest ofrough rice and grain sorghum in theSouth,

eal othThe meal moth, Pyralis f arinalis

Linna eu s, ? is brown ish somewhatlarger than the Indian meal mothth ough it varies in size , and usuallyhas a wingspread of about I inch.


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-.

STORED GRA IN INSECTS 17

BS J078Figure 20.- Mediterranean flour moth: adult dOfS view with wings spread; 8 . adu lt side

view in resting position: C larva; Dpupa enlarged ; E abdominal joint of larva enlarged .Adult moth has a wing expanse of slightly less than I inch.

Figure 21C shows the characteristicmarkings or pattern of the forewings.T hey a re lig h t br own wi th d arkbrown pa tches at the bases and tips,and each forewing has two wavy,t nsverse white lines.

Th e meal moth is widely distributed and, in the larval stage, is a genera l feeder upon cereals, cerea l products, hay, and many types of driedvegetable matter. It is usually foundin damp basements or in other placeswhere acc um ulatio ns of d ampspoiled gr i n, br n . or mea l a refoun d . Though it prefers materialthat is damp and in poo r condition,the meal moth may attack a ndseverely damage sound wheat orcerea l products, if these mate rials arestored in moist places or have a relatively high moisture content.e l moth l rv e so met imes

ttr ct much ttenti on because oftheir capacity to web-up and bindtogether seeds of various kinds. The

larvae cut through bu rlap sacks andcan damage them grea tly when heavyinfestations develop in the sack edmaterial. Figure 22 shows the characteristic w ebbin g togethe r of infestedseeds i n th is inst ance navy beans).Figure 23 shows the tendency of thelarva e to sp in th eir whiti sh silkencocoons on the outside of grain sackswhere the sacks tou ch one another.When the larvae cut sacks, the seedsfa ll out and lodge where the sackstouch . In such places, the seeds areusually heavily infested .

The meal moth la rva is whitis h,and, when fully grown, is about Iinch long fig. 21B). Th e la rva showsa cont rast between the black of thehead and the first body segment andthe white of the remainder of thebody. The body of the larva is oftentinged with orange toward each end .

The larvae spin peculiar tubes ofsilk that contain mixed particles offood material T hey rest in these


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1 8 AGR ICULTURE H ND OOK NO. 500 U.S. DEPT . OF AGRI CULTURE

A B c\ . 0 J

Figure 21. - Mt al mot h: A pup a an d (ab ove webbed grai n mass with portio n 01 pupa protruding; E two well-grown larvae and (right) smalle r larva: C two ad ult mot hs. arkings onfor ewings easily dist inguish this insect from ot he r grain pests. Magnified about 1 1/ 2 times.

tub es. which are very tough. and feedfrom the openings at the ends . Whenfu lly grown. th e larvae leave th etubes. spin silken cocoo ns (a lso oftenco vered w ith foo d particles). andtransform into pupae (fig. 21A fromwhich the adu lt moth s lat er emerge.

Th e female moth lives about I

Figure 22.- l :av) beans. webbed together bymeal mo th larvae, adhere to sack.

week and lays 200 to 400 eggs. Insummer. the period from egg to adu ltis 6 to 8 weeks.

B\; JIHIFigure 23.- Whitish cocoons spun by meal

moth lan..ac on side of sack previously filledwit h infested seed . Note da rk pupae with incocoons, vet ch seed ebbed to sa ck by la rvae. and (center) adu lt moth .


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STORED GR IN INSEGTSGR IN ND FLOUR EETLES

19

CadelleTh e ca de l le, enebroides mau-

ritanicus Linnae us ,s is an elongate.oblong. fla ttened . black or blackishbeetle about one-third of an inch longfig. 4A is sometimes ca lled thebolting-cloth beetle becau se of itshabit of cutting the silk clo ths ofbolting reels and redressing machinesin flour mills.Th e cadelle larva is one of thelargest of the grai n-infesti ng insectsand is eas ily recognized . is aboutth ree-fou rths of an inch long. fleshy.

Coleop tera. ' rogo'itidilc

with the bdomen terminating intotwo dark horny points fig. 248 . Thelarva bod y is a dirty or chalky white.and the head. thoracic shield . andtwo horny points are black .

This insect is widesp read over theworld a nd is freq uently fo und inmill s. granarie s . and sto reho uses.where i t infest s flour . meal andgrain. Both the larv a and adull feedon grai n and have the destructivehabit of go ing from kernel to kerneldevouring the germs . The cadelle isone of the longest lived of the insectsth at attack stored grai n: many of th eadulls live for more than I year andsome of them fo r nearl y 2 years.

HN30 PN5177Figur e 24.- Cadelle: fl adult, about one third of an inch long; ri ht larva, abo ut three-fourt hs

of an inch long.


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20 AGlllClJLTlJllE HANIlIlOOK NO. eoo. Ui l OF-no o r AGIl IClJLTUIll : I.......k becl . . i_her I,fe and. und.... I onob ,.n1l Y .bou, 1.000 CWn.. I , .. e1u....... .. .....cp;> ill lood ,eriaL.. bid. lul teh . .

7 oIO .... hcf.110c romplftc: .oci 0,, 11,,, 1 10 14 mon,ho ..... ,I>cn _ k .......--.sed p in .. hich 0 I.., .J_,nu, 1M 1 p 1 . . . , . . 1hq I.....ucndbaR 0 , he limb.... llc ho n or0 ,.c. pad. Ih . , ho lch ,h .i l nl ed ma'C'rial. h ,I>c . ...... aa.h l l l u n I i... r , I , pcrid .. i,hou foo d .nd h .n um a,nhidd.n in ,h. ,, .. o,k I h. hin10 a I n, ,im f ., ,h. ~ . n ha.bcC1I te mo.ed, When ......, . in i . pu,,n ,he hin. i hccomc. inl ed ,na. tpn n. ly l Io 11m .sawloothed Grill Bee n.The ..._ 1Iocd , ra,.. becl le, ()f-r -

po b .............u fL '. . . . .k .. of oAc bnl k........ .be coo. . . . . . . . .1l&II , . . . .. . pn l II .1111. lor_ .. bert. . aboul 111 of............... It p ,n. h Ilhe pccoIiar oIlUClte of IIIc h onoa... hi< o han t i. ....1001I1hkc P F, inn. 01\ h id I f 2 ~ I, . loId ..in botll the aI . tid adu l . . . . . . .. allfd of ,, ,..ahl. on,in f'CCially , . in and . , .in p,,,do< . _ h a.noo . .. m I. b Hu 1,1Od. oc k.nd poollry feed.. < p,a. nUl melcar.d n, . r.d dried rUIl .Thc adol h . , on .n a, . to10 10 mon h.. bol ..,mdolll mayliu Ion, a. ) , can. 1loc f.......l.

._< -

..... h i . n _ t_ .-- ,_-......\left. . Y aJ 10 ;,;, CU She d . . . .llIom Iocrtdy . 1110 I....,hcuff OCluck> lhem in lo .. erc>>a: irt . kcmclof lIJ. in. 1M . man. oIC1ldc1. .. II en> IuItd1 ill ) 10 , dll)Tile ...... ,;n Ia. . . . . del . . . . . . loIl...Ihin in. 1e .,ain \luI . ra. l abooaa ,\'Cly .r.d feed . Oorin ommc .Ih.,., hccomc folly n in .boo, 2..t t h . 1 h. mllu Ia lh. n oon.1..,


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21

.' .daled pIn . , h. mad ant,rain b11r. Or ph,h., ..... /1(hUHIl: .. ftC CORfu.... , ,10 'ht'... . , >l1lN r , bc eIk II I t rom I) (lUnd In fi lII I h.il ,IK. . . . .l oo lMd ,no,.. Mri lot and p ~to pl . h&n , ,

In , hanl , , . , l>coo1 lr . M C d...m ,1., hlda (lftat ly ...em >, on form. C . ndcol ... . II I t n . . 1 l . ....Ion . pol_. . h ~ n dd h-h u . M it . ' ho . . . ,,,,,,hl,k, r OjM l


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22 AGRICULTURE HANDBOOK NO. 500 U.S. DEPT. OF AGRICULTURE

BN-308SFigure 27. Squarenecked grain beetle adult,

about one-tenth of an inch long.

a great variety of plants. It is one ofthe most common beetles in storedcorn in the South and, in the cornfields, is always found on damaged orexposed ears.The immature stages closelyresemble those of the sawtoothedgrain beetles in both form and habit.The larvae have the bad habit ofdevouring the germs of the seeds inwhich they breed. These insectsdevelop from egg to adult in about 3weeks.

oreign Grain eetleThe foreign grain beetlehasverusadvenaWaltl ,9 is a smallreddish-brown beetle somewhat sim-

Bar in appearance to the closelyrelated squarenecked grain beetle, butis shorter and stouter fig. 28 .Though of worldwide distribution,it is not important as an enemy ofstored grains. It is attracted to dampand moldy grains, where it feeds onthe molds. This insect is rarely foundin clean grain.Mexican Grain eetleThe Mexican grain beetle, Pha-r xonoth kirs hi Reitter ,10 is a

highly polished, deep-brown beetleabout three sixteenths of an inchlong. It somewhat resembles the confused flour beetle in general appearance but can be readily distinguishedfrom that insect by its more polishedsurface and longer antennae fig.29AThis insect is common in Mexicoand Guatemala, where it breeds ingrain and grain products, but it is notknown to be established in the UnitedStates.Siamese Grain eetleThe Siamese grain beetle, opho- teres pusillus Klug ,8 is a flattened

reddish brown beetle slightly lessthan one-eighth of an inch long. It ischaracterized by the much flattenedmargins of the thorax and wingcovers fig. 30AThis insect first appeared in thiscountry in exhibits of rice and cerealfrom Siam, Liberia, and Ceylon atthe Columbian Exposition, and it isnow well established in the Southern

IOColeoptera Languriidae.


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BN 3 86Figure 28. Foreign grain beetle adult.

States. It is commonly found in ricemills in Texas but does not causeserious damage.

lat Grain eetleThe flat grain beetle, rypto estes

pusi us Schoenherr), is one of thesmallest beetles commonly found instored grain. It is a minute, flattened,oblong, reddish-brown beetle aboutone-sixteenth of an inch long, withelongate antennae about two-thirds aslong as the body fig. 31). It is cosmopolitan and is one the the commonest insect pests of stored grain.However, this insect is not a primary

pest of stored grain, and the adult isa p pare n t1y unab1e to su rv ive insound, uninjured grain. It follows upthe attack of the more vigorous grainpests and is frequently found in enormous numbers with the rice weevil.This insect is a scavenger and ofteninfests grain and meal that are inpoor condition.

The females deposit small whiteeggs in crevices in the grain or dropthem loosely upon farinaceous material. The larvae are particularly fondof the wheat germ, and, in infestedgrain, many kernels are found uninjured except for the removal of thegerm. The larvae also feed on deadinsects. When fully grown, the larvaeform cocoons of a gelatinous substance to which food particles adhere.They transform into the pupal stagein these cocoons and later emerge asadults. Under favorable conditions,this insect may develop from egg toadult in about 5 weeks but theaverage period of development insummer is about 9 weeks.

A related beetle C. tur usGrouvelle), resembles the flat grainbeetle so closely in appearance andhabit that it is usually confused withthat insect. This beetle, also, is cosmopolitan and the females of the twospecies are so similar that it is almostimpossib le to distinguish betweenthem. The males, however, can bedistinguished from each other by thelength of the antennae. The antennaeof the C. turcicus male beetle are aslong as, or longer, than the body, butthe antennae of the flat grain beetlemale are only two-thirds as long asthe body.


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2 4 AGRICULTURE HANDBOOK NO. 50 0 . U.S. DEPT. OF AGRICULTURE

8 :\ 3081Figure 29 Mcxican grain beetle: A adult; B larva: pupa: D leg of larva; E antennaof larva

A B and C enlarged about 8 times: D and E greatly entargec .

Rusty Grain eetleA thi rd species, the rusty grain

beetle ryp t o lestes [e rrugineus(Stephens). is similar to the Oat grainbeetle and turcicus beetle inappearance and habit , but differsfrom them in the antennae (fig. 32) ofthe male beetle. which are not moreth an half as long as the body. Thisspecies is more resistant to co ldweather than the oth er two speciesa nd is mo re commonly found instored grain in the No rthern States.

onfused Flour eetleTh e confused flour beetle, ribo-lium confusum Jacque lin du Val, is

a shiny, flatt ened. ova l. redd ishbrown beetle about one-seventh of aninch long . Th e head and upper partsof th e t horax are densely coveredwith minute punctures The wingcovers are ridged lengthwise and aresparsely punctured between th e ridges(fi g. 33) . This insect is distributed

Cole optera. Tcnebriomd ac.


31/64

A

rfOREDURAlS ISS],rtS

c

~ ~A \ I .,)II ,

,.h f110' i,. h UI I y . hut . um. h ; r . ~ I>nknm.n 10 l.. lun, . ~ l ... . . qmon,h., Thot ~ lay. an , ~ul .bou t &50 ~ , , . . htdI . . malland h n ~ ,n flour or nlhcrfood tmal ,n Inch ,hot a d u l l . l , , ~

~ . r ~ t


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21> iI. acetle, It can he

d H n ~ u I , m lhe n nlu-e< fh,u rheetle nh wllh th< . id of a ~ n o

n ~ ~ a , , The . ~ < n ,, the , lu-edfl u< I>ee


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27I he p ,n,,um .. j ~ . , h e middle1he d,II. ,.......... hcI ,..n theJ aU . h .. n ,n fl,uU ,14

I hI> .....1 e a n d ~ . . . . . . ,ed l h thc . nlu Cd n.... 0011 andha ,mda I .cd,n, and h,c.d ,n,h,; h l . Ih. mma . a,... or ,h. ,n: rc ... , n,I., ,ha, 11 ,mp .... ,hl. I d , , ,u ,..tI hot .....,hcII I hc .k d pm.n t..1 rc.idII. W h 1 ..1 . .>me-.. h,; , ,ho c , d...n , he , ...I..

.. , ....Ie \ I ,h ,I , .m p lll.n . , h, .cd rh..., hoo1 le

..nd m . , . m m n l} ,n ,h .... .. ,hc,n n, t, d c. , ,h . . . ... u . c , ,,,,, ,. d........ ,,, .,np ju. , . In ....d ..... ,,, lhe d. .....,

... u . , ~ ed,n, . ,h ,n...,.,n,I -> a .... u . . u ......,11 .nd , . , . ,,,lhe ma, .1 I nl ....., I , . ,he . .{u....-d 11 .., lie. ,h. ,ed 11 .., .....,1

i, p m . a 1 < f milled r d .....II ,. r ,n , a .h,pm. n ... he, , aU..., ,, l} . . d .. and,he . 1. ..... ,,{ h , . ... ~ . a h. .,.. ,. ...., a p m ~ ,...... ,, m .....taal.h,p , ,,

American Black FlourBeetlel he A.......... n hlac flo. , . hoo1k.

T Io< o I_ . . a ~ a d . . Iounda-.tornmon/}oun., II . .

>n.tnh l , lItl .......f...od, h {he ~ .... ,a ll -Ir...l t a ~ ,h ,h I ~ n in

P I ~ and kahil IIi, 3 ~. I ...... , h ...> . . , ,.11 k_ n a. theeonl..>ed .nd I ftl n,,,,. hoo11oo-. I ...imila, h,; h,. . and ,. ... a,. , nd nl .... , ,n and , ra,prod .,. ,n II , mill< and Kh ........

I _ - -0_ -- = ,...,__, ,- -- _ _,,,---


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28 A G I U C U L T U l ~ IlA oI I:lBOOK / ;0 . MO , u a . DEn , Of AGRICULTUln;

JS.- H , 01 .


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STORED GRAIN INSECTS 29than one-eighth of an inch long. It issomewhat similar in form to the confused flour beetle but is narrower andis pale yellowish brown fig. 35BThe beetle is further differentiatedfrom the confused flour beetle by thepeculiarly shaped antennae and theminute canthus behind each eye.

The longheaded flour beetle hasbeen reported from most parts of theworld as having infested wheat, rice,corn, barley, rye, flour, and similarproducts. It was first recognized inthis country from specimens collectedin Texas in 1908 and is now widespread in the Southern and MiddleWestern States, where it is commonin rice and flour mills. This beetleinfests grain and grain products inthe mills and causes the same type ofdamage as that done by the confusedflour beetle.

Slenderhorned FloureetleThe slenderhorned flour beetle,

Gnatocerus maxillosus Fabricius), is closely related to the broadhornedflour beetle and is of similar form andappearance fig. 35C). It is about oneeighth of an inch long. In addition toits smaller size, this insect may bedistinguished from the broadhornedflour beetle by the slender incurvedhorns with which mandibles or jawsof the male are armed. Its habits aresimilar to those of the broadhornedflour beetle, but it is less common inthe United States and is more or lessconfined to the Southern States.

Smalleyed Flour eetleThe smalleyed flour beetle, Pal-orus ratzeburgi Wissmann), is the

smallest of the flour beetles thatinfest grain and grain products in thiscountry. It is tiny, somewhat oblong,flattened, shiny, reddish-brown beetleabout one-tenth of an inch long fig.35D This insect occurs throughoutthe world and is widely distributed inthis country. It breeds in grain andmilled products and is frequentlyfound in flour-mill basements.

epressed Flour eetleThe depressed flour beetle, Pal-orus subdepressus Wollaston), is

similar in appearance and habits tothe smalleyed flour beetle. It isslightly larger than that species, andthe sides of the front of the head arestrongly reflexed and extend backward to conceal the front portions ofthe eyes fig. 35E In the smalleyedflour beetle, the sides of the front donot extend backward. The depressedflour beetle, also, is cosmopolitan butis much less common in the UnitedS ta tes than the smalleyed flourbeetle, except perhaps in the GreatPlains.

roadhorned FloureetleThe broadhorned flour beetle,

Gnatocerus cornutus Fabricius), owes its name to the peculiar structure of the mandibles, or jaws, of themale beetle, which are armed with apair of broad, stout horns. It is astout reddish-brown beetle about


36/64

3 0 AGR IULTUR HA ND BO O K NO . 5 0 0 , U.S . DEPT . OF AGRICULT UREo nes ixth o a n inch lo ng. and itclosely resembles th e o ther flour bee-tl es in a ppeara nce b u t is easily di s-t inguish ed fro m them b y the peculiarstructure of its jaws fig. 36). t is cos -mopolitan and is common in all partsof the United Sta tes, excep t in theGreat Plains. where it is compara-tively rare. This insect prefers to feedin flour and meal but is found in avariety of grain s. T he adult beet lesfreq ue ntly live for I yea r o r lo nger.Th e fe m a le la y s 10 0 to 200 sma llwh ite eggs which ha tch in 4 to 6 d a ysin warm weathe The developme ntperiod from egg to adult is 6 to 8week s.

Larger Black FlourBeetleThe la rger hlack flour hec tic, yn-

aeu i an JtuJ Le Conte j. ? describedin IX52 was little known as a pest ofsto red grain and grain products until

when it was found in a flourmill in Seattle. in stored wheat inKansas. and in sto red co rn in Iowa.

It is now fairly common in farm-sto red g rain in the Nort h CentralStates. It is a stout. reddishbrown orbla ck hectic about one fourth of aninch lo ng ig. 37 . Th is insect isknown to live fo r 6 months and may

\-J094 1:\ JfN5 H: -J096Figure J6. roadhorned flour beetle: l eft larva: C f fI{f r . pupa: ri1 I / . adult Adult is abo ut one-

sixth of an inch tong


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O R un GRA IN INSf:L- rS

. .. . . . . t? 1M, . . IIbd . _ . . . . . ~ h ..

II. . ro. I...... I ~ a r u n d ~ b , or.. b , nd ,t , ,. lb . ~ q < l ~ fmm

~ ~ to ~ d u h nn I cmpl.loo in 4.. cel . ,


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32 AGRICULTURE HAND OOK NO 500 US DEPT OF GRICULTURE

B\ JO HFigure L Eggs o f fl our a nd grain road ho rned flour beetle: H cadellc: C.

Medit erranean Oour moth l confused flour beetle. Photo greatly enla rged

MEALWORMSThe term mea lworm applies to

th e larvae of severa l beetles of thefamily Teneb rionidae that are nocturn al and frequent dark places. Theybreed in refuse grain co arse cerealand mill product s tha t accumula te indark corners under sacks in bins.and in sim ilar places. T hey inhab itmoist pl aces a nd a re o ften foundamo ng slightly damp bags.

Yellow MealwormThe yell ow mealworm, Tenebrio

mo to r L in naeu s. is o ne o f thelargest insects that infest stored cerealproducts. This insect is cosmopolitan;

in the United tates, it is abundan tonly in the Northern St at es.

T he ad u lt is a po lished d a rk brown or bl k be et le some wha tmore than half an inch long (fig.39A . Its tho rax is finel y punctured ,and its wing covers ar e long itudinallyst riated or grooved. The fema le laysbean -shaped white eggs covered witha stic ky sec retio n tha t ca uses theflour. mea l. or grain waste in whi chth ey are placed to ad here 10 them.Th e eggs ha tch in about 2 weeks ands lender white larva e emerge. Thelarva e soo n turn ye llow and assumethe fo rm shown in figu re 9C When


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STORED GR N lNSEt J S 3 3

A B

cF_ . _ _ . _ c..D


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AGRICULTURE HANDBOOK NO. 500 U.S. DEPT. OF AGRICULTUREfully grown, the larvae are about Iinch long and are yellowish, shadingto yellowish brown toward each endand at the articulation of each segment. The yellow mealworm gets itsname from the yellowish color of thelarvae.

There is but one generation eachyear. The adults begin to appear inthe latitude of Washington, D.C., inlate May and early June and may befound until late in August. Thefemale beetles are quite prolific, andeach may lay as many as 500 eggs.The larvae become fully grown inabout 3 months, but, instead of transforming into the pupal and adultstages, they continue to feed and moltuntil cold weather and then hibernate. Later on, in late spring or earlysummer they transfo rm into thepupal stage for about 2 weeks.

Because the yellow mealworm hasbut one generation each year and isentirely an external feeder upongrains it is not a serious pest.Screening and fanning will easilyremove it from grain shipments. Thewell-grown larva, however, can doserious injury to whole grains undercertain conditions, when grain is heldfor long periods without beingmoved.

ark MealwormThe dark mealworm Tenebrioobscurus Fabricius. is very similar

in form, size, and color to the closelyrelated yellow mealworm. However,the adult is a dull, pitch-black beetle,

in contrast to the shiny or polisheddark brown or black yellow mealworm adult (fig. 39B The darkmealworm larva so closely resemblesthe yellow mealworm larva that it canbest be distinguished from that species by its much darker color (fig.39D

These two species are often foundtogether since they have similarfeeding habits. The overwinteringlarvae of the dark mealworm begin topupate earlier than those of theyellow mealworms, and, in the Washington, D.C., area the adult beetlesemerge during April and May.

Lesser MealwormThe lesser mealworm, Alphitobius

diaperinus (Panzer),11 resembles theyellow and dark mealworms in formand color but is considerably smaller.I t is black or very dark reddishbrown and is three-sixteenths to foursixteenths of an inch long (fig. 40AThe larva is yellowish brown andclosely resembles the young larva ofthe yellow mealworm in form andappearance (fig. 40B This insect iscosmopolitan and is commonly foundin flour-mill basements in damp ormusty flour or grain. It prefers grainand cereal products that are slightlyout of condition and is commonlyassociated with poultry feed.

lack Fungus eetleThe black fungus beetle, Al-phitobius laevigatus (Fabricius), is


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STORED G RAIN INSE(TS

- - -almo. t id. ntic.1 in pp n.,. 10 th.I. . mu l...o .m . nd h , imilh in , II p.d . . . dlmp, moldy Sin.nd ceru l p o d ~ Ind doe. nol

c a ~ ,nOllI d. mli 10 s o ~ n d , in,Thi. ;n>t m. y b< d l l g ~ i o h e d f.om1 M: Ie


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AGRICULTURE HANDBOOK NO 500 US DEPT OF AGR ICULTURE

ED

B

Figu re tt c Black fungus beetle larva; B pupa; adult; Dcaudal segmen t of larva: Elateral pla te of pupa l ana i abou t I inch long

li:\ 5179F igu re 42 Redh o rned gra in beetle adult

abo ut one fourth of an inch long


43/64

STORED GRAIN INSECTSDERMESTID BEETLES

37

In general, the dermestids are agroup of beetles that scavenge andfeed on animal matter.. Certain species, however, belonging to thegenera Trogoderma Anthrenus andAttagenus vary their diet by feedingon farinaceous materials. They arefreq uently present in flour mills, farmgranaries, warehouses, and similarplaces where grain) and grain products are stored.

Black Callpet BeetleThe black carpet beetle, Attagenusmegatoma FabniWius),12 is a small,

oval beetle two-siateenths tal threesixteenths of amiDdllong fig, 43AThe head and tJlDrax are black, butthe wing coven; are black or darkreddish browm _ are covered withshort hairs. Its; t p and antennae aredark yellow; The larva is very characteristic and can be easily necognized.It is reddish or golden brawn, is covered with short, scalelike, appressedhairs, and: bas a tuft of bog hairs atthe end of the body fig, 44).

The Larvae are often found inabundance in cracks mthe floors ofwarehouses where foodstuffs haveaccumulated. In the spring, theselarvae transform into adults, whichswarm over bagged material steredthere. Because the larvae of the blackcarpet beetle develop slowly, there isonly one generation each year. If conditions are unfavorable, the life cyclemay be prolonged to 2 or 3 years.The adults, which emerge in thespring and early summer, live 2 to 4

weeks, and each female lays; about100eggs. This beetle is cosmopolitan.

Trogoderma Beelll a 12The best known m m r of this

group is Trogoderma inclusumLeConte,12 which is a common pestof grain, seed, and other stored products in the Great Plains SUates. Theadult beetle is one-fourteemth to onesixth of an inch long. 1 hlc female isabout 1-1/3 times the size of themale. The beetle is redtilLsii brown toblack with indistinct pater markingson the wing covers.

The larva is stout, 31Dd at rest, theback is yellowish brown fig. 45).However, the areas between the segmmt5, which are visible during movemmeJIt and the underside are very paleydlow. The last three segments of thebody are almost covered by tufts ofdense, specialized hairs. The fullygrown larva mag attain a length ofone-fourth of an inch. This insectlarva is difficult to distinguish fromthe larvae of r te species.The adul t female beetle lays up to96 eggs. The life cycle varies from 7weeks to several years, dependingupon the temperature and the foodsupply.

Trogoderma glabrum Herbst isvery similar to T inclusum and isfound in similar situations. The adultlacks the longitudinal pale markingson the midportion of the wing covers,and d if fe rences in the eyes andantennae of the two species can nor-


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38 AGRICULTURE HANDBOOK SO 500. DEPTor A RICULTURE

A __B

f_ I . - _ _ A. i _ H.l_ _ . _ < _ 1

1 D , 1F Ai


45/64

STOR F.O CRAIN INSf:CT S

1,. ,_ I. . or r< IIt r h ,. , . 1>< ,h ' 01 .n ,,>0ma lly ... determ,ned nl y in r la bo,aw ry fLg, 4JB), The lar.ae arc also ery ,im lat. but T. glahrum la aearcelie.h KoJnma Iahile Ih l lo ( TpaTahlle eal). i, ide,pead bUl d iffi olt , g n i 7 C beeau of irs an able appearance.

Wo rld , ide, lhe khap a hottlle,T iI If Tma K,aa rium hen< . ilh em,,,t d lro li\ < of this gfOUp (fig.

. , 4< I.,,, . > d o ; ..1,, ,I


46/64

4 AGRICULTURE HANDBOOK NO. 500 U.S. DEPT. OF AGRICULTUREan eradication program was started.By 1961, active infestations wereeliminated and strict quarantinemeasures have kept the beetle frombecoming reestablished in the UnitedStates.This beetle prefers dried vegetablematter to animal matter as food butwill attack almost any kind of eithermaterial Grain damaged by thekhapra beetle has somewhat the samea pp ea ra nc e as g ra in a tta cke d by thelesser grain borer.

Under favorable conditions, thekhapra beetle -breeds so rapidly thatthe larvae often appear in large num-bers in the surface layers of binned

grain. The larvae crowd into thecrev-ices of building, bins, and so forthand are difficult to reach withinsecticides. Since this beetle has limited mobility, it spreads principallyth ro ugh the agency of man.

Other species of Trogoderma inthis country that may be confusedwith those mentioned here are T.grassmani Beal, : om tum Say), Tsimplex Jayne, and 1 stemale Jayne..All these species are .sometimes con-fused with the nthrenus species,which are not grain pests. The variedcarpet beetle, A verbtUCi Linnaeus),.however, has been found in mills andstorage facilities fig. 43Q

SPI ER BEETLES 3Several species of beetlesbelonging to the fanHly P ti ni da e are

occasionally found i nf es ti ng gra inand cerea l products They attractattention by their peculiar, spiderlikeform. These insectsare rather widespread in distribution but are rarelyabundant enough in the UnitedStates to cause serious damage.

Hairy Spider eetleThe hairy spider beetle Ptinus vi -liger Reitter), ? is a reddish-brown

beetle marked wi th four irregularwhite patches. It is about one-seventhof an inch long fig. 46). Th is insect isa rather common pest in the PrairieProvinces of Canada and is occasionally destructive in the adjoiningNorthern United States. It attacks

I3Co)eoptera, Ptinidae.

stored grain and all types of :p-oundcereal products The adult beetleappears in warehouses in the .springand lays eggs in flour, feed. or othercereal products The female laysabout 40 eggs. U nd er favorable conditions, the development period fromegg to adult is about 3-1/2 monthsThe full-grown larvae construct char-acteristic silken pupal cases, whichare covered with food particles fromthe food material in which theyoccur.

An allied species, raptorSturm,is about as common in Canada as thehairy spider beetle.Whltemarked Spidereetle

The whitemarked spider beetle, tinusfur Linnaeus), is also foundin the Northern States and is some-


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srORED GR N INSE S 41.

\\

.

Figure 4b Hail spider beetle adult. ahout

o ne-sevent h of an inch long.

what more abundant than the hairyspider beetle. whi ch it closely resembles in a ppearance a nd habit s fig.47). It feed s o n both a n ima l and plantmat ter and atta cks flour, feed . gra in.a nd m isc e lia neou s fo odstuffs. It isra re ly a b u nda n t e no ug h t o ca useserious damage.

rown Spider eetleT he b rown spider beetle. Ptinus

clavipes Pan zer), clo sely resem blesthe wh itemarked spider beetl e in size.co lo r. gener l ppe r ance. andhabits. It mal be di stinguished fro mthat beetle by th e absence of whitemarkings on the wing co ve rs.

Other Spider eetlesThe Australia n spid er beetle. Ptnu s

ocellus Brown. has been reported from

th e United S ta t es but is rar ely fo undhere. t is very similar in generalappearance and habits to the br ownspide r beetl e.h e m er ican s pi der bee t le.ezium am ricanum Laporte) . is asma ll spider beet le of striki ng appear-ance . It ha s a s h i ny. s u bg lo bula rbody th at dis tinguis hes it from th ep receding spid er beetles fig. 48). It issomewhat of a scavenger and feedson dried a ni ma l p rod ucts a nd plantmatter. t is no t an important pest ofsto red grain or grain prod ucts. but itis occasionally found in mills, wa rehouses. and dwell ings,

A losely related spec ies. ibbiumpsvttoides Czenpinski), resembl es theAmerican spider beetle in appearanceand habits and is found in similar sit-ua tions. It may be d istingui shed fro mtha t insec t by th e head an d thorax .which are d ensely co vered with small

/

8 ) 103Figure spider adul t

female. The elo ngate-o val male is not socon spicuously marked as t he female .


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42 AGRICULTURE HANDBOOK NO. 500. U.S. DEPT. OF AGRICULTURE

B 30Higur e 48. merican spider beetle adult.

Photo enla rged.

scales and scalelikc hairs. This speciesreportedly occurs only in the extremeso u t h e r n p t ion of t he ni te d

S ta tes. whereas M ffine (Boieldieu)is the common form in the NorthernStates and ana da.

MISCELLANEOUS BEETLESTwobanded Fungus Beetle

The twoba nded fungus beetle. I-phitoph gus i sci tus (Say). is asmall. handsome. elongate-ova l beetles light ly less tba n one-eighth of aoinch long. It is reddish brown withtw o broad bl a ck hands across thewing CWeT fig 49 . This insect isdistributed over the world and. as ascavenger. generally feeds on suchmaterials as fungi and molds in refusegr a in a nd gr in produ ct s . a nddecaying vegeta ble matter. t is frequently found a round mills an dstorehous es where waste material isallowed to a umul te and in wet ordamaged grain in the holds of grainsh ips . T he larvae h ve been reared inmo is t cor nme l a nd in s poi ledcereals.

Hairy Fungus BeetleThe hairy fungus beetle, yph e

erorea (Linnaeus), : is frequentlyfound in cornfields. where it is apparently attracted to the decaying kernels of exposed cars. After corn isharve st ed a nd shelIed . it is o ftenheavily infested by this insect. butthere is little feeding on undamagedgrn in, Thi s beetle is cosmopolitanand is fou nd in all parts of the UnitedSt ates in dwellings. warehouses.stores. fl our mills. granaries. and similar places,It is a small brownish beetle aboutone-tenth of an inch long and is ov-ered with ha i rs (fig . 50). t rat he rclosely resembles the drugstore beetle


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43

. t ...... _ ._ _ . . . . ,. . . _ :00 . . . .

- ,

,.I

1m.

\ ,or j ' , un and ,her 1I . . I ,m, and ,n Ih. . . . .1' . dm ,

fro m ,nju re d p l.nt> II ,m . . f , I < d ,-, cdun n d I .oe< milh I ....h III ~ m u L o i o n . f h . l ,..,.., It . . f ... -eon ,n u.m ra.. l . . . . . .... of , i a,\ d o.d ) b t .. J f>tnl t . ( ' , . >pIu I I ...,.100 ..... 1 I n . m ~ , I I _..hich .. a. ' ' ' If,ld,,.'fd tr m ah road . . .

h Q . ~ and ahundut,.. thn c,ou tr). It m,b. , I fo.....0 CO I> wp t tf. hut ;. h t f ~, ~ n d .. a n,f ..... -h,n) . d ~

,n n c ~ . .'. . but >mallcr(fiB- ~ I n I l in_ , ,'an al,, ' I>e e. I}d l ~ u h . d f, ,,m ,h . d u ~ , l O .hec,l. b) tbe ' No pe ur it. an,.. .' '' Hob arC . I. , a l. ,n, lcad ur r . ~ u

,,,a l . _Corn Sap Beetle

I he ,' ,n ' 01' . . tl. C I I,hdU>J l m ( }-. hr i. ;u. ), rna) h.lud i l) r.< In i , cd h) II , ptlul iar ' nl .,n.. hb . .. '''0 andh uncnk . h , hln roh..nl . ,n, ....' . . . andI t onc-I ,n>l II ) ld . in 01-

1__ . . . . . , _ ....... _ _


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\. j A(JRICUL-nme IIANOI,U K so . WO, U,S. m:PT. ()f AOIi ICULTU EI ...n all o,cr. II> haM . arc or)mIL., 0 , 110 01 tllc o ulnc-Icnlh 01 aR inch n ~ I II. . ,,, . . .l und in all ,cmp. . . ... ' uhl , p 'al. . ~ ; n . ,of , . 'oh , ,, .tld O \ a n ~,h 1 p.,>dU


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Drugstore BeetleI d ~ h > h.... lull) n . he} r ura e ,n. mall -. ..... . I h. onl . hi . Ie h< , ,-cd ,n I... , than n h,

Calorama Beetles\ 1


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16 AtJlUCULTURE HANDBo o K : -0 , bOO U. S OEPT. O f AOll lCULTURE~ < u n ..o k I


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16 AtJlUCULTURE HANDBo o K : -0 , bOO U. S OEPT. O f AOll lCULTURE~ < u n ..o k I


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STORED GRAIN INSECTS 47bodied, louselike insects with fairlylarge heads, poorly developed eyes,and long slender antennae (fig. 56).These insects are about one twentyfifth of an inch long. They feed on agreat variety of organic matter , bothof plant and animal origin, but aretroublesome through their presencealone, not because of the actualdamage they cause.

Some females are believed toreproduce without mating, but malesare sometimes found with them. Eachfemale may lay as many as eggs,and, in summer, the developmentalperiod from egg to adult is about 3weeks. The newly hatched youngresemble the adults in form and general appearance but are smaller andlighter in color. These insects arewidely distributed in North Americaand Europe.

A closely related species, the largerpale booklouse, rogium pulsatoriumLinnaeus), known as the deathwatch, is similar in appearance andhabits and is found under the samecircumstances. It may be distinguished from the common booklouse by its slightly larger size, diminutive wing covers, and well-developedeyes. This insect, also, is widely dis-

BN 31 9Figure 56.-Booklouse or psocid adult.

Enlarged.

tributed over North America andEurope but is not quite so commonor abundant as the preceding species.

SILV R ISHThe silverfish or slicker, epismasaccharina Linneaus. ? is commonly

found in mills, warehouses, anddwellings. It is a shiny, silver orpearl-gray insect with three long, taillike appendages, which make it easy

IlJThysanura, Lepismatidae.

to recognize. It is cosmopolitan andfeeds on starchy foods of all kinds. Itis particularly found in dark, moist,warm situations.A closely related species, the firebrat , hermobi domesticPackard), is found in similar situations and closely resembles the sil-


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48 AGRICULTURE HANDBOOK NO. 500, U.S. DEPT. OF AGRICULTUREverfish in appearance and habits fig.57 . This insect may be differentiatedfrom the silverfish by its broaderbody. It is pearly white and is heavilymottled along the back, with duskyscales that give it a banded appearance when some of the scales haverubbed off. It is cosmopolitan and, insome areas of the world, is moreabundant than the silverfish. Thedevelopmental period from egg toadult is II to 12 weeks.

BN-311OFigure 57.-Firebrat adult, about 2 1 4 times

natural size.

COCKROACHESThe familiar cockroaches are fre

quently found in establishments thatcon ta in cereal products. They areparticularly abundant in the basements of buildings in dark, moist situations, and, when lights are suddenly turned on, it is not uncommonto see the floors almost black withthem. The oriental cockroach, l ttorientlis Linnaeus, is probably thecommonest species found in flourmills and food establishments in

2Orthoptera. Blattidac.

North America. It is a large, darkbrown or black roach, about I inchlong at maturity fig. 58 . The femalesare unique because they have shortwing pads but no functional wingsfig. 58A The males have fullydeveloped wings fig. 58B

A closely related species, theAmerican cockroach, eripl netmeric n Linnaeus . is also quite

abundant and is the predominantform in many flour mills in theSouthwestern and Midwestern States.I t is larger than the oriental cock-


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STORED GRAIN INSECTS

BN-3055Figure 58. 0riental cockroach: adult female; B adult male; C, adult female side view ; D

half-grown cockroach. Enlarged.

roach and frequently is 1 1/2 inches characteristic irregularly shapedlong. This insect is bright sienna reddish brown double spot in thebrown except for the brownish center fig. 59 .yellow pronotum which encloses the


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50 AGRICULTURE HANDBOOK NO. 500. U.S. DEPT . OF AGRICULTURE

/

-3111figu re 59.- American cockroach: 4 adult (do rsa view); r i ht adult (ventral view). Enlarged .

FLOUR OR R IN MIT ST he flou r or grain mites arc pal e.

grayish white. smoo th. wingless. softbodied c reatures. The) a re microscopic in s iz e and have nume rouslong hair on the legs and hack (fig .60). M i t e s arc not tru e i ns ec t sbecause the adults have eight legs andth e body is indistinctly divided int otwo par ts. T he 110ur or grain mites.usually less tha n onc-fiftieth of aninch lon g. arc much smaller than th ebooklice.

:IAcarina. Aca ndac.

They are of ten fnund in storedgrai n and occasionally increase innumber s so ra pidly that the grainseems to be quite alive with them .Du ring heavy infesta tio ns. their castskins and dead bodies accumulatei n to fluffy . lig h t -bro wn ma ssesbeneath the sac ks o f grain. II theseaccumu lations are on a warehousefloor, they ro ll up into piles. wh ichmove about with each gust of wind .No other group of gra in pests pro-duces these masses. Wh en p resent inlarge num bers. th e flour o r gra inmites promote swea ting. impart a dis-


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BN 5180Figure 60. Grain mites. Greatly enlarged.

agreeable odor to the grain and maycause damage by feeding.Fortunately the mites that attack

grain are preyed upon by predaceousmites which usually become abun-dant enough to kill the grain mites ina comparatively short time. If notscreening and fanning the grain willusually reduce grain mite infestationsto a point where no injury occurs. carus siro Linneaus known asthe flour mite common forage mite

or grain mite is the most injuriousspecies of mite found in flour grainand cereal products in NorthAmerica. t multiplies very rapidlyunder favorable conditions and maycomplete its life cycle from egg toadult in slightly over 2 weeks.

Species of the genus Tyrophagusand other related genera also knownas flour mites or cheese mites arecommon in grain. They are similar inappearance and habits to siro


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AGRICULTURE HANDBOOK NO. 500 U.S. DEPT. OF AGRICULTUREPARASITES OF GRAIN PESTS

Swarms of small wasplike insects,of the size and appearance shown infigure 61, are sometimes found inbulk grain. Similar insects may alsobe seen on the windows of flour millsand other establishments where cerealproducts are handled. These insectsare not harmful to grain but arebeneficial because they attack anddestroy the insects that infest grainand grain products.

The small parasite shown resting ona kernel of wheat in figure 61 is theadult of nisopteromalus calandraeHowardj.P the most importantparasite of the rice and granary weevils. The female wasp can detect thepresence of the grain-weevil grubhidden from sight within the grain andparalyzes it with a few thrusts of theovipositor. She then deposits one egg

Hyrncnoptera, Pterornalidac.

BN-3056Figure 61 Anisopteromalus calandrae H.

adult, a hymenopterous parasite of grainpests, resting on a wheat kernel.

on the exterior of the grub or in closeproximity to it. The egg hatches, andthe parasite grub feeds on the paralyz-ed weevil grub and destroys it. Thedevelopmental period from egg toadult is about weeks. One femaleparasite wasp is known to lay as manyas 283 eggs, but the help usually comestoo late to prevent damage to the crop.A related species, Choetospila elegansWestwood.P is somewhat less com-monly found as a parasite of the sameinsects.Figure 6 shows another fairlycommon parasite of the grain beetles.This insect, Cephalonomia tarsalisAshmeadj.P has habits quite similarto those of the preceding species.

Figure 63 shows the adult of raconhebetor Say,24 attacking flour mothlarvae. This little wasp is one of themost important parasites of these

Hymenoptera. Rcthylidac.24Hymenoptera Braconidae.

BN-3113Figure 62 Cephalonomia tarsalis A. adult .

Enlarged.


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ST R D GRAIN INSECTS 5

B

\ 14Figure 6 Uran in hehetor S adult female in th ree poses: feed ing on body fluids of

Mediterranean flour moth lnrvu with straight ovipositor protruding behind: J in position forpunctu ring body of larva preparatory to laying an egg: C with ovipositor well inserted in larvaj ust before laying an egg


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54 AGRICULTURE HANDBOOK NO. 500, U.S. DEPT. OF AGRICULTUREmoths. It first paralyzes the flourmoth caterpillar by stinging it severaltimes. It then deposits several eggs onthe paralyzed caterpillar. These eggshatch into small, white, footless,grublike larvae that suck the bodyjuices of the caterpillar. Under favorable circumstances , this parasitedevelops from egg to adult wasp inless than 2 weeks.

The species enturia canescensGravenhost), is even more important as a beneficial parasite of the flourand meal moths. This slender wasp hasa reddish-brown abdomen, black headand thorax, and reddish-brown toyellow legs fig. 64 .

The habits of this parasite aresomewhat different from all the abovementioned parasites of grain pests.The adult wasp deposits eggs inside thebody of the flour moth caterpillar, andthe entire development of theparasitic larvae, until just beforepupation, takes place within the host.The host caterpillar is not paralyzedand continues feeding until theparasitic larva has become nearly fullgrown. The developmental periodfrom egg to adult is 3 to 4 weeks.

25Hymenoptera, Ichneumonidae.

BN-3115Figure 64 Venturia canescens adult

Enlarged.

Grain dealers and millers not infrequently find a small, threadlike,white worm, about three-fourths of aninch long, in accumulations of flour orgrain dust fig. 65 . This worm is thelarvae of a small black fly, cenopinusfenestralis L. 26 known as the windowpane fly because it frequents thewindows of mills and similar establishments fig. 66 . This worm doesnot injure grain or cereal products butis a predator on other insects found inmills and warehouses. A closelyrelated species, Scenopinusglabrifrons Meigen. is also known asa windowpane fly.

2flDiptera, Scenopinidae.


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H\ -J Figure 65.- Lan of windowpane fly. enopinusfenestrtis ( 1.. ). abou t three-fourth s of an inch

long. Lan a preys upon gra in beetles and mites.

; -

insects in grain

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