2 5 2 8 2 5 :~ Illp·8 11111 . 11111 11111 1.0 1.0 i~ . 3 2 Bkl: 1111/,32 2.2 .,lA 11111 . .2 I" 36 I" .z 11111 .: ~F6 I:' ­ I'· "' I~ :: ~m~ I­.: ,~ ~ l..;L,:,1.O. '- " 1.1 1.1 La.. ,­ -- -- 11111 1.8 111111.25 /////1.4 111111.6 111111.25 1111/1.4 ~ 11111~·6 MICROCOPY RESOLUTION TEST CHART MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF STANOAROS-1963·A NATIONAL BUREAU Dr STAN£1AHOS·1963 A :1<f:~ . TEcliNICALBuLLETIN~~==~~.="=' No. 351 _ '='~.\III~.J.~=~.~=======_ APIUL, 1933 UNITED STATES DEPARTMENT OF AGRICULTURE WASHINGTON. D. C. 'LIFE HISTORY. OF THE ANGOUMOI8. .. ~ GRAIN MOTH IN MARYLAND . • ~J:J By PEREZ SIMM;ONS, Entomologist; and G. W. ~LLINGTON,t Assi8tant Entomologist, . DiVision of StoTed Product In.~ecw, Bureau of Entomology 2 CONTENTS Page Page , :.. Introduction________________________________ 1 Lif",his.tor~OVIp05.lt""l <;letails-Contint:ed.______ ._______________________ ·16 " ~ The AngoumoL. grain moth in wheat and ."'~ ~ corn~ ___ ..... ___ ... ___ .. ________________________ 2 Incubatioll period______________________ 19 Larval period___________________ _________ 20 ::<l ."': Annual cycle of the moth on :Maryland 2 "" _ farms ____________ ,____________________ Pupal period____________________________ 24 f_.~ Ef,Tects of some farm practices on moth Development from hotching to emer· :Ji :',f Increasc._______________________________ 3 gencc_________________________________ 25 Overwintering of the insP.Ct..____________ 3 Effectstemperatl on development Ires ________________________ oC high and low "'_ 28 Spring dispcr.;al to growing wh~aL______ 5 ;.; Thewheat Angoumois________________________________ grain moth in seed _ Comparative rate oC development oC thfi Ii sexes _________________________________.:. 30 <': Dispersal to cornfields ________ ._________ _ 12 Parasit.es____________________________________ 31 ~ - Life-history details ________________________ _ Outbreaks, past and Cuture__________________ 31 Behavior of the adults ________ . __________ 14 Summary__________________________________ 32 Longevity of adults_____________________ _ 14 15 Literature cited____________________ _________ 34 IN'l'RODUCTION More than 500 articles on the Ango ..mois grain moth 3 have been published, but only a few of them report original information about ~ the life history of the species. Rearu-uur (7, p_-'·4.97)4 and Duham"l en du Monceau and Tillet (4.) in France, Oandura (3) in Italy, and ~King (6) in Pennsylvania have been the chief sources upon which C'\! entomologists have depended for biological information_ The work C\l of the writers, begun in May, 1923, at the Sligo (Montgomery ~ Oounty), Md., laboratory of the Bureau of Entomology, was con­ iC( tinued until the close of the summer of 1927. Four reports on certain :E phases of the work have been published (5,8,9,10). In this bulletin the writers present their .final reports on the work, with brief refer­ ences to conclusions arrived at in their J: revious papers. The laboratory work was conducted in a dwelling house used as a field laboratory and in an outdoor insectary. The sides and ends of the insectary were of wire netting over which, on the sides exposed to I Died Aug. 23, 1932. 'The cooperation oC O. W. Acorn! oC Colesville, W. F. Garber, oC Glcnmont, and F. A. BIUndon, of Silver Spring, Md•• was most helpCu and Is grateCully acknowledged. 3 Silo/Toga. etTealell!/. OUv.: order Lepidoptera, family Geleehlidoe. 4 Italic numbers in p&Tcnthesis reCer to Llteraturo Cited, p,34. lfi6816°--33----1 € 2 _,TECHNICAL BULLETIN .351, U, S. DEPT. OF AGRICULTURE ..; '. , mtect f sunlight, there was a screen of cotton cloth. Land at ethe station and wheat fields and cornfields of several farmers were used for ceI:te.ID. experiments. Except in the cas6 of expHriments withhigh and low temperatures and overwintering, the detailed life-history operations were co~dtlCted under room temperatures wIllch. rose end fell markedly, especially during the winter. THE A.NGOUMOIS GRAIN MOTa IN WHEAT AND CORN The agriculture of the winter-wheat region east of the Appalachian Mountains, consisting typically of rotatiot;ls of corn, wheat, and clover, pro'Vides an environment for the A..ngoumois grainmoth that is prob­ ably more favorable than that of any other wheat-growing region in the Unit~d States. E,en during years when climatic conditions do , not favor outbreaks of the in.;ect (9)-and such years are fortunately in the majority-the year-round food supplj- of corn and ,vheat,' both in storage and lipening in the field, assures the diffuse perpetuation of the species. When weather conditions favorable to the insect occur, its reproductive powers are emphatically demonstmted, much to the concern of growers and millers of wheat. In the region which includes Pem•..i.vIYania, New Jersey, Delaware, Maryland, Virginia, and North Carolina, wheat was harvested by approximately 345,000 farmers in 1919 (2). In Maryland alone about 26,300 wheat grow­ ers, comprisin@: 54.8 per cent of all the farmers in the State (2), have been subjected to losses during years of unusual abundance of the . species. In the latitude of Maryland wheat is the only crop seriously aJ­ fee ted by the Angoumois grain moth. Barley, rye, pop com, and other seeds are sometimes infested, but losses in these grains are comparatively small. Damage to the large crop of field com is unim­ portant; but the corn, bein~ larO'ely used on the farms where it is grown, is in storage on a consldera~le proportion of the farms through­ out the year and serves as an important reservoir of infestation until the new whent crop comes on. ANN!.'AL CYCLE OF THE MOTH ON MARYLAND FARMS The moth popUlation reaches its height in the new wheat crop during the summer and early fall. Being an important cash crop, the wheat is to a large ext,ent r~moved from the farms before the advent of cold weather, and only small, scattered supplies are left in the hands of growers. In the meantime, however, the ripening corn has become slightly but quite generally infested; and the insect passes Ii the winter in the corn stored in bins, in scattering lots of held-over wheat, in waste wheat in straw, litter, and screenings, and to a small extent in barley, rye, and other seeds. The moths can enter or leave at will the various types of buildings used for corn and wheat storage in Maryland. During the late fall, winter, .and early spring moths are not in e'Vidence, but they begin to emerge in May and fly to near-by fields of ripening wheat. At this season very little of the last year's wheat is left on the fanns, and the corn supplies are diminished and frequently small. After the new crop of wheat is threshed and placed in storage followin~ har­ vest in late J·une or 'early July, the moths attain their maxunUlll abundance, ANGOUMOIS GRAIN .MOTH IN MARYLAND 3 Breeding is most rapid during the three months from June 15 to September 15, and is practically at a standstill from November 1 to May 15. Spring emergence begms about the middle of May in central Maryland. The adults of the first generation usually begin to emerge from new-crop wheat about themiddJe of July, but in favorable years some emergence may occur {{.vo or three weeks earlier, in \vhich'~ase it coinci8es with wheat harvest. The generations overlap and become mixe<i; Probably not more than three generations develop to their maximum numbers during a year in Maryland, but in exceptionally warm years the rate of d6velopment probably is increased to a point where there may be four generations. EFFECTS OF SOME FARM PRACTICES ON MOTH INC:REASE In Maryland the usual method of harvesting wheat, following the operation of cutting and binding, consists of piling the btmdles or sheaves into round shocks for curing. The shocked wheat is some­ times threshed in the field, but in most localities the sheaves, after drying for a time in the shock, are either stacked or piled in mows in barns or sheds for further curing. Although stacks are frequently made in the fields, the sheaves are more commonly taken to the farm­ yard (near stored grain and other moth sources) and ate stacked there or placed in mows. Holding the grain in the straw to allow it to undergo 11 I.sweat " or further ripening and drying process pro­ "ides conditions fa.vorable for moth increase. After the wheat is threshed it is either sold promptly or stored in bins which are ordi­ narily nut stuted for fumigation. 'Wheat straw, always containing more or less waste wheat, is some­ times allowed to remain in the field where the threshing was done, with the result that wheat growing near by the following year becomes infested. Straw piles are often made in the feed yards, in order that the straw may be eaten by livestock and trampled into compost, or it is often baled for ease in handling or for sale. All such straw is a potential source of moths which may infest near-by ripening corn in the fall and. growing wheat the follo"'ing spring. However, as shown bv the condition of samples taken from shocked wheat near old straw piles, straw that has been exposed during more than one winter is negligible as a source of mothB. OVERWINTERING OF THE INSECT Of special interest and importance in a study of the activities of the Angoumois ~rain moth are the facts about the stages in which the insect passes the winter and the time of appearance of the first adults in the. spring. Detailed information about the life of the adults (p. 15) suggests that moths not given drinking water do not survive more than five weeks; that only a few, living under more favorable conditions, exceed that length of tlffie i and that none live more than 52 days.