Historic, archived document Do not assume content reflects current scientific knowledge, policies, or practices Ce a CIRCULAR No. 269 WASHINGTON, D. C. A PEST OF CURED TOBACCO, EPHESTIA ELUTELLA HUBNER By W. D. Reep, Associate Entomologist, and ErskiNE LIvINGSTONE and A. W. Morritt, sRz., Junior Entomologists, Division of Stored Product Insects, Bureau of Entomology CONTENTS Page Page En trod UCN cree eee rn Oe Deh Dee 1 | Life history and habits.—Con. Records of infestation in tobacco____-_--------- 3 Rate of development on tobacco___________ 7 I. Como mie shiStOnys Soe = ee SL 3 Data on mated moths. 222.2 = eee 10 Observations of stages of Ephestia elutella on DISGMSSTO nes ie he kU Bae Ss a eho 12 LOLA CCOMM Ae stars nbeyoenat Lor Gs pay BSL ca 4 SUERCTEEN GUO. Meet SIE CU erie oe a eae ss 12 DVRS NERS a Sa ae a ae 4 Natural enemies found attacking Ephestia Athen anyiAe esa saa te 2 oor SRS Se 5 CUUACL Grea eae eee ied he Ll Ry Pe 12 ARES. OVD OW) DA es a a ae ee a 5 The work of larvae i tobacco-___-_-__-_--_--- 14 Aner GU Sie Ve eae ec ey 5 the proplemomeontroly =) 2s aaa 14 pe ebife misionyama habitse ss os! Sei eae eee 6)./] SET a ayes eee i Saye Gu tate tn 8 ae 15 Apparatus and method of study ----------- 6) | Witeratiunercited sasee 2) Ur ee ee en 16 INTRODUCTION The phycitid moth Ephestia elutella Hbn. has appeared in the bright- tobacco belt of the United States as a pest of flue-cured tobacco. The infestation was discovered on August 8, 1930, as reported by Back and Reed (/).! Up to that time the cigarette beetle (Lasioderma serricorne Fab.) has been regarded by the tobacco industry as the most destruc- tive pest of cured tobacco. The appearance of the new pest and the possibility of its further spread have aroused the industry, and many inquiries concerning the insect have been received from tobacco dealers. The larvae of Hphestia elutella attack the brighter grades of flue-cured tobacco, eating much of the leaf between the veins and otherwise mar- ring the appearance of tobacco in hogsheads and cases. The mere presence of the insect may cause the tobacco to depreciate in value. The work of larvae on leaves of flue-cured tobacco is shown in Ficure 1. Jack (6, p. 32), in writing of the importance of EF. elutella as a pest of cured tobacco in Southern Rhodesia, said: Tobacco manufacturers in Britain take a very serious view of infestation with this insect, and infested bales of tobacco are depreciated in value far beyond the value of the leaf actually destroyed or damaged. Consequently this pest is to be regarded as a menace of the first importance. Observations on the moth in tobacco warehouses have been made at frequent intervals since its discovery there. On June 22, 1931, life-history studies were undertaken in the laboratory at Richmond, Va. The purpose of this circular is to make available for the tobacco industry the results of these studies as far as they have progressed. 1 Italic numbers in parenthesis refer to Literature Cited, p. 16 163725°—33 CIRCULAR 269, U. S. DEPT. OF AGRICULTURE : : = : —e FIGURE 1.—Individual tobacco leaves illustrating the work of Jarvae of Hphestia elutella in cured Excrement of the larvae may be seen attached to the webbing along the larger veins of the tobacco. leaves A PEST OF CURED TOBACCO, EPHESTIA ELUTELLA HUBNER 3 RECORDS OF INFESTATION IN TOBACCO Ephestia elutella was recorded as a pest of cured tobacco in Russia in 1915 (9, p. 7). Ina weekly circular issued by the tobacco section of the Bureau of Foreign and Domestic Commerce ? September 9, 1930, attention was called to the appearance of the larvae of L. elutella in stocks of tobacco held in bond in one of the London warehouses, where it was feared that the work of the larvae would cause the value of the tobacco to depreciate materially. This London infestation occurred in tobacco imported from Rhodesia, Africa. Mokrzecki (8) published in 1931 a bulletin i in Polish on the life his- tory and control of Ephestia elutella in the tobacco warehouses of Poland. The following information regarding the occurrence of this insect is quoted from the German résumé of this paper as translated for the present writers: The author has inspected the damage done by the larvae of Ephestia elutella in Simferopol and Yalta (Crimea) during the years 1909-1917 and described its biol- ogy in general terms. He furthermore had this pest under observation in the storage buildings in Sukbum (Caucasus, 1911) and in storage at Philippopol (Bulgaria), 1921. * The larva has been A tei into Poland with bales of tobacco leaves purchased in Bulgaria and Greece, and Ephestza elutella is found at the present in the tobacco storage houses of Poland. The author had an opportunity in 1929 and 1930 to inspect about 20 tobacco factories and storehouses in Poland, and to convince himself that the main infes- tations of tobacco came from Bulgaria and toa lesser extent from Greece and other countries, and that these importations were more or less infested with larvae of Ephestia elutella. Bovingdon (2) recorded in the August 1, 1931, issue of the British trade journal Tobacco the appearance of the moth Ephestiaelutellain stores of tobacco in England, Bulgaria, Russia, and the United States. Jack (6) published in January, 1932, an account of the appearance of E’phestia elutella in stocks of tobacco in Salisbury, Southern Rho- desia. He stated that up to that time it had not been found in Rhodesia anywhere except in Salisbury. He also stated that the moth had been found infesting tobacco in Bulgaria in 1928. ECONOMIC HISTORY E’phestia elutella has been recorded as attacking many dried vege- table products and has been carried in these products by commerce to all parts of the world. Réaumur (11, p. 275-277) in 1737 gave an account of a moth that injured chocolate, and it is conceded that he referred to E’phestia elutella. Chittenden (3, p. 9) said that the habits of the moth had been known in Europe since early in the seventeenth century but that American records showed nothing positive regarding injuries by the species. Maskew (7) published an account of the appearance of H. elutella in a shipment of walnuts imported at San Francisco, Calif., from Manchuria, and regarded it as a serious pest of walnuts. De Ong (4) reported: ‘Large shipments of peanuts infested with the currant moth, Hphestia elutella Hiibner, were repeatedly received at the San Francisco port from China during the fall of 1924.” Munro and Thomson (10, p. 22) reported this moth to be the most 2 UNITED STATES DEPARTMENT OF COMMERCE, BUREAU OF FOREIGN AND DOMESTIC COMMERCE, TOBACCO DIVISION. THE TOBACCO SITUATION IN SOUTH AFRICA AND SOUTHERN RHODESIA. U.S. Dept. Com., Bur. Foreign and Dom. Com:, Tobacco Div. ‘Tobacco Markets and Conditions Abroad no. 270, p. 5-7. 1930. [Multigraphed.] 4 CIRCULAR 269, U. S. DEPT. OF AGRICULTURE important insect affecting cacao in London. Gibson and Twinn (4, p. 29), writing of Canadian conditions, reported the presence of £. elutella in Canada. Zacher (12, p. 47) recorded the insect as occurring throughout the warmer parts of Europe and extending as far north as the southern part of Sweden. Reports of occurrence in the United States and Canada indicate that this insect has been widely distributed by commerce in these countries. Additional localities from which this insect has been re- ported are Africa, Australia, China, and many tropical countries, including Ceylon, Java, Sa- moa, West Indies, Brazil, Costa Rica, and Panama. How- ever, none of these records of occurrence refer to the insect as a pest of tobacco, ex- cept those already mentioned, from Russia, Poland, Bul- oaria,Greece, Africa, England, and the United States. It will be inter- esting to determine, if possible, whether the iniestation in to- bacco warehouses in this country is the result of a foreign importation of Hph- estia elutella that normally feeds on tobacco, or whether the species in the United States, nor- FIGURE 2.—Egegs of Ephestia elutella laid near the midrib of a leaf of < flue-cured tobacco. X 25 mally feeding on various stored food roducts, has begun to acquire a taste or preference for tobacco. b bap) OBSERVATIONS ON STAGES OF EPHESTIA ELUTELLA ON TOBACCO THE EGGS The eggs of Ephestia elutella are elliptical and are grayish white when laid. Viewed through a binocular microscope, the shells appear to have a granular texture. They are about one-fortieth to one-fiftieth inch long, and are visible to the unaided eye on tobacco leaves. There they are laid either singly or in small clusters. A small cluster of eggs attached to a leaf of flue-cured tobacco near the midrib is shown in Figure 2. The eggs, when deposited, have soft shells which harden soon after exposure to the air. In clusters they sometimes press upon A PEST OF CURED TOBACCO, EPHESTIA ELUTELLA HUBNER 5 one another and have distorted shapes when the shells harden. The grayish-white color of the eggs changes to hight brown during the incubation period. The newly hatched larvae emerge from eggs through circular openings in the end, and the eggshells, retaining their original shape, often remain attached to the tobacco leaves, THE LARVAE The larvae on tobacco vary considerably in color; some are tinged with yellow; others are brownish, white, or pinkish. Their bodies are sparsely covered with col- orless hairs. The young larva begins feeding soon after hatching, if suitable food is available. When tobacco leaves are hard and dry the young larvae have difficulty in feeding, and there is heavy mortal- ity when they are fed on tobacco leaves that havea low moisture content. The larvae devour the tender parts of the leaf, between the veins and the midrib, and pellets of their excrement are often attached on silken threads spun by them. Full- grown larvae usually range from three-eighths to five- eighths inch in length (/0) (fig. 3), and brown spots on the dorsal side of the body segments give them a striated appearance. They crawl rapidly when moving about among tobacco leaves or when searching for a suitable place in which to pupate. THE PUPAE FIGURE 3.—Larva of Ephestia elutella, X 42 (approximately). The natural length of the larva in tobacco is about three- eighths to five-eighths inch. (Munro and Thomson) The pupae (fig. 4) range from light brown to dark brown in color, the variation being due to differences in age, as pupae turn darker brown as they grow older. In length they range from three-eighths to five-eighths inch, approximately, and they are usually incased in silken cocoons. The locations chosen by the larvae for pupation are not definite. In tobacco warehouses they pupate in spaces between staves of hogsheads, in the tobacco near the surface of the hogsheads, or where, in crawling about in warehouses, they find sheltered spots suitable for building cocoons. FIGURE 4.—Pupa of Ephesita elu- tella, X12 (ap- proximately). Thepuparanges fromlight brown to dark brown in color and is usually incased in a silken co- coon. (Munro and Thomson) inch (10), screen doors, walls, hogsheads, and boxes. THE ADULTS The coloration of the adults (fig. 5) of Hphestia elu- tella is variable; some are gray, others light grayish brown. The head and thorax are brownish and the abdomen is pale gray. When the wings are folded the moths average about three-eighths inch from head to tip of wings, and the wing expanse is about one-half In infested warehouses moths can be found resting on Occasionally they may be seen flying during the day. Observations in tobacco warehouses revealed that moths are more active at night than during the day 6 CIRCULAR ZOO US. DEPT. OF AGRICULTURE and that the rapidity of flight is much greater at night. In the day- time the moths are attracted to dim lights and are most numerous in the shadows cast by rows of hogsheads. LIFE HISTORY AND HABITS APPARATUS AND METHOD OF STUDY Female moths of the spring brood were collected in tobacco ware- houses during the period -June 22 to July 14, 1931, and records of their egg laying on flue-cured tobacco were made. ‘The females were probably fertilized when collected; however, males were placed with them during the oviposition period. The progeny of these moths were used to secure the life-history data tabulated in this circular. In order to obtain egg-laying records, the females were placed in individual glass vials, each containing portions of leaves of flue-cured tobacco. The vials used were 4% inches long and 1 inch in diameter, FIGURE 5.—Adult of Ephestia elutella, X 9 (approximately). When the wings are folded the adult measures about three-eighths inch from head to tip of wing. (Munro and Thomson) and had close-fitting metal caps. Fresh pieces of tobacco were placed in the vials every 24 hours, and the eggs were counted with the aid of a binocular microscope. During the incubation period the daily lots of eggs, usually attached to the leaves, were left in the vials. The larvae were reared in circular pasteboard pill boxes 1% inches in diameter and three-fourths inch deep. As food for the larvae, por- tions of flue-cured tobacco leaves and tobacco which had been ground through a 48-mesh screen were used. It was found that young larvae had difficuity in feeding on the tobacco leaves after some of the mois- ture had evaporated. This difficulty was overcome by using the ground tobacco in the rearing containers. The temperatures recorded in Table 1 were obtained from the rec- ords of the United States Weather Bureau for Richmond, Va. The other temperatures recorded were obtained with a hygrothermograph located in the laboratory. A PEST OF CURED TOBACCO, EPHESTIA ELUTELLA HUBNER 7 RATE OF DEVELOPMENT ON TOBACCO 3 Table 1 contains data showing the developmental periods of 30 individuals of H’phestia elutella that hatched during June and July, 1931, and Table 2 contains similar data for 30 individuals that hatched during August. TaBLe 1.—Data on development of Ephestia elutella from eggs laid on flue-cured tobacco in the laboratory at Richmond, Va., during June and July, 1981 | Period from egg to adult Incuba- Date Temperature 2 Rearing No. Dacre tion rave Fupat adult Sex has period Pp Pp emerged Dura- tion | Mean | Mean maxi- | mini- | Mean mum | mum Days | Days | Days Days Os OM, oat Ler) Saati June 2 6 Aug. 13 | Female-_-_- 51 89.0 69. 9 79. 4 OMI ie hy eel do 5 35 9} Aug. 11 | Male____-_- 49 89.8 70. 1 79.9 Beto NS tans | Ls a do 6 36 OF ATIE. “Ton Eead Ouesnne 51 89. 0 69. 9 79.4 Ae ak ih a ES i dows 5 41 11 | Aug. 19 | Female__-_- 57 89.0 69.8 79. 4 Sere ee Ete ao eas dower 5 47 13 | Aug. 27 | Male______ 65 87. 4 69. 0 78. 2 Gini ate Fos Se do 6 42 10 | Aug. 20 | Femaie_-__- 58 79. 8 69.8 74.8 FOS sie Pe SU) doze! a 61 OO Sept. mom and oEses see 77 80. 3 68. 2 74.2 Rie Beate Aiea! June 24 5. 31 OB AMT Seimei | eae Gl O wate 45 89.8 70.3 80.0 Caras Os ae | does 5 37 UT ATS Gg | eee Ob eee 53 88. 6 69.9 79.2 fh eee eee eva douzes4 5 45 LU PAT ADAG eee Ose 61 So 69. 4 78.4 TT baie ete Es 8 done" 5 44 NAS PAtis= 2268s d Osa = 63 87.4 69. 1 Thek, Deh ie Shee dole-== 5 31 OR AUS. Om plVlalebaa== 45 89.8 70. 3 80.0 1 IS eh see a oe June 25 5 33 7} Aug. 9 | Female___- 45 60. 1 70. 4 80. 2 i saris eS ie | ea do 5 39 I) Aug. 19))\) Male = - 55 87.4 63. 6 75.5 is tee ees er ogee dows 5 49 11 | Aug. 29 | Female____ 65 86. 2 67.8 77.0 1 eas es aa eee doe 5 55 HORE SCOUT ON 2G Olean 70 86. 2 67.6 76.9 jee ae ae dome 5 47 145 Ass 30 Rl aan d Ouse == 66 86. 1 67.8 76.9 18tse Se June 26 4 4] } |] Ares is) | ol = 5 87.5 68. 0 Teel OE oU ae Riles June 27 5 43 14 | Aug. 28 | Male___-_-- 62 86.3 68. 1 77. 2 9) eae eases June 28 5 53 9 | Sept. 3] Female__-- 67 86. 2 67.8 77.0 Die ee PRES July 7 3 42 1 | Says 2 | Clos 57 85. 7 67.4 76.5 GT ae ks eee [ee do= = 4 33 13 | Aug. 26.) Male___-_- 50 85.8 67.9 76.8 OB YS hie EPR epee) Be dos 4 38 WE AS Olbs TL one 56 85. 7 67.5 76. 6 Aatwial files Se) dos = 4 53 O) isos Il ClO 66 85. 6 66.9 76. 2 A SN irae aA EO July 8 4 29 AS PAULO: 24m ween Osea 47 85.8 68. 2 WHeO Oy pias tae aha ehoe (ates done 4 38 LS SO, Sa COE = 57 85. 7 67.4 76. 5 OF ae ate dows 4 48 1G) Vso SB Leet 62 85. 4 66. 4 75.9 Qe see mee cals C July 10 4 38 1B] TSO Bb Close eS 55 85. 5 67. 2 76.3 {8 aes ee 2 ale July 17 5 66 T25OCt eS wemalesa== 83 85. 9 65. 1 75. 5 Seer cate ees July 18 4 72 LOB Och ZininVialeaan: 95 83. 8 62.8 73.3 Average____-____ 4.8 43.4 CUSVES 3 Sena = cp Meal yaaa Aa gk OOF Onions ene Cem LE Shs ee | i | a The temperatures recorded in this table were obtained from the records of the United States Weather Bureau, Richmond, Va. 3 A. W. Green, field assistant at the tobacco insect laboratory, June to September, 1931, assisted with some of the life-history studies recorded in this circular. 8 CIRCULAR 269, U. S. DEPT. OF AGRICULTURE TaBLE 2.—Datia on development of Ephestia elutella from eggs laid on flue-cured tobacco in the laboratory at Richmond, Va., during August, 1931 | | | | | Period from egg to adult A lercubat Date Temperature! Rearing No. ee | tion Leave Zepe adult | Sex | period | Pp Pp | emerged | Dura- i | ; tion | Mean | Mean | | maxi- | mini- | Mean | | | mum | mum | | | I | Days ; Days | Days Days sie Cone ey Be Pe Seas eo | Aug. 9 | 4 47 13 | Oct. 12 | Male_-___ SL.1| 719) 76.5 ieee ees ee feat 6s ee 4 53 18 | Oct. 23 | Female__-_- 75 80.8 69. 1 74.9 5 a ee oe ns SO ie dolss 4 53 18 |_do Beer ee doe eee 79 80. 8 69.1 74.9 Be tal Se 8 | Aug. 11 | 6 35 15 | Oct. 6| Male_____ 56| 80.8| 723 76.5 ips Ee eae = do 6 4] 15 | Oct. 12) Female-——- 62 80.8 V7 76. 2 Geka Se Ue ee LEG bres 6 40 20 | Oct. 16 | Male______ 66 80. 6 70. 8 75.7 7s ae Wa iadge ee 6| 44 16 |aido! 15°} dass 66| 80.6| 70.8 75.7 TUE he She gdowees| 6 | 43 17 |Sedol fe) ado 66| 80.6| 70.8 75.7 G2 ae eee do--:| 6 | 46 15 | Oct. 17 | Female___- 67 | $0.6 70. 6 75. 6 OLAS eee oe doe2 6 | 46 | 15: | ae ole dO ae 67 80. 6 70.6 75. 6 if Ea caper a | PRE do 6 | 44 17 |..-do eo Male______ 67 80. 6 70. 6 75. 6 yg ie Sc a degres 6 | 47 17 | Oct. 20 | Female__-_- 7 80.5 69. 6 75. 0 pile ee | SC Pee See 17 |eeeie = | FS dy mes 7 80.5 | 69.6 75.0 if eee eee ee hes W@s eee 6. 47 18} Get. 21 | Male---.- 71 80. 6 69.4 75. 0 pee Re dete 6) aR 170 eee Be) Gere 71| 80.6] 69.4 75.0 (is SEES Aug. 13 5| 38] 13] Oct. 8 | Female__ 56| 81.2| 72.9 77.0 [i pea el ae dose. 5 | 38 | 13) dose | Male: —--- 56} 81.2 72.9 77.0 Tf ee Se Be demic: 5 | 41 | 16 | Oct. 14 ; Female-___-_ 62} 80.7 71.1 75.9 ieee ee Tel hee By. 4a Sig | Gelaet? | Malesets 5 65| 80.7| 706] 75.6 Zak oe pel Sree Meee dos 2 5 | 46 | 14 |) Sde-- = Female____ 6511) 1 S0l% 70. 6 75.6 A; id (a a see A des 5 | 45 | 1G (et 18s dos 66 | 80.6 70. 3 75. 4 oath AS does 3 46 | 13 | iQer 28 | dos s*. 69 80. 7 69. 4 | 75.0 pr 8 ie a bl oles 5) 48 18 | Oct. 23 | Male __ 7. | SF | eR ee 7 eas Boe ee dos 5 | 54 12 |exdowe Female___- 71 80.7 68.9 | 74.8 Dye eek eye ee do: 5 48 19 |Seedon te doicees 71 80. 7 68. 9 74.8 OG ee te Moet Aug. 14 | 6 43 | 19: |\Qets 920' |, Males 67 £0. 7 69. 6 75.1 7 en ES fe Aug. 16 | 5 | 44 18: | M@ek. 2 225)_--do=-= = 67 80.8 68.9 74. 8 7 eee ee do-=*. 4 &3 | 24 | Mov. 5 |---da-_ =": - &1 80. 3 66. 3 73.3 Sgt aie XC Aug. 17 6! Sel 17 | Oct. 22| Female__| 66] 80.7] 688 74.7 Si ee es ea te Ea do 5 | 51 24 | INMGVi9.0 5°15) doz2= 80 80. 0 66. 2 73.1 AVeRAGG (2 see = 3.3 45.4 16:7 | See eee | Bea eae FS it Prim (Geese jes | Ae eee i 1 The temperatures recorded in this table were obtained from hygrothermograph records in the labora- tory, Richmond, Va. A PEST OF CURED TOBACCO, EPHESTIA ELUTELLA HUBNER 9 TABLE 3.—Data on the life history of 30 mated pairs of Ephestia elutella on flue- cured tobacco in the laboratory at Richmond, Va., 1931 Date of emergence K Longevity Dae recon anes, euee average Pre- Wil= || OStqs | aaa. 2 oan hateie, Bal Maar Reo BY by aes ovipo-| posi- | ovipo- Roe rae temper- NG anor ee sae 5 laid Fi Bi aN ce thy pe ; period | period | period | y e- axi-| Mini-| Aver-) during Male Female Male eile hatch mum|mum| age | | life of female ? Num-| Per Days | Days | Days | Days| Days| ber cent | Days| Days| Days| ° F. Pe ees July 28 | July 28 0 10 1 9 11 183 75. 4 5 4 4.1 84.5 DEE July 31 | July 31 0 4 1 4 5 126 | 81.7 6 AW Zo 84. 2 Sha | eae Coes ss |e dose 0 4 1 3 5 108 94.4 7 4 4.3 84, 2 Asap: Aug. 2N Aug. 2 0 5 2 a i 104 | 86.5 7 By) fs 83.5 yee Pua CL a PES) domes 0 6 3 6 10 Li Gel 7 DelEOnO 82.4 Gees Aug. 4] Aug. 4 1 4 1 7 6 76 | 92.1 6 Sys bul 83.3 ERS Bs Aug. 5j| Aug. 5 1 10 2 13 13 211 78.1 7 4 4.5 79.6 Sie es Aug. 6] Aug. 6 1 4 2 9 if 148 | 93.2 7 4|] 4.3 80. 2 ES Aug. 7 | Aug. 7 1 7 2 12 10 138 | 65.9 7 by WW a TI 79.1 10 Pee pAUS. 8 | Aue s8 il 3 6 10 10 95 | 35.8 8 5} 6:0 78.8 ieleeeay ee PATO apt gail el Owes 1 4 1 8 6 144 | 79.9 9 lh Gy8 78.3 12ers TAI te (On Aa TS 1 3 2, 10 6 134 63. 4 7 5 5. 4 CE” 13__._| Aug. 10 | Aug. 10 0 8 1 8 9 120 | 64.2 8 AG nose Wl & 14____| Aug. 11 | Aug. il 1 4 1 10 6 101 41.6 6 4 ONS 76. 1 15e S22) Ate. 125) Ane. 12 3 3 0 5 6 37 78. 4 9 4 4.7 Wa ® 1Ge = |pe= does See doses 2 8 2 Gj 12 113 | 79.6 8 4) 4.5 (tss,.4 ieee | CAO Lon AIO m ls 2 7 0 11 9 103 | 68.9 9 4) 4.7 eel 18____| Aug. 14 | Aug. 14 2 5 0 10 7 144 56. 2 9 5 6. 2 78. 7 RG raG Ee SO sae te EEG (eee 0 i 3 8 10 IDB ZAZA 7 4} 4.6 hay 2023417 Auge. 16); Aus. 16 1 7 2 8 10 84 te? 6 6 6.0 75. 0 Qe eee AUS AGE Anos 19 0 6 2 10 8 83 | 63.8 8 On Ge 6al 358) Baas 5 eae date: NEO (Oe 1 8 3 8 12 93 | 24.7 7 Sl Ee 74.6 Dee PATIO =e 20" eA oes 20 0 7 2 10 9 WAR Bish, 7/ 8 Ne (a) 73.4 DA \eAtIoe ah Kh AIS 2k 1 i 0 12 8 99 | 71.7 7 4} 5.6 Tey 33 25___.| Aug. 24 | Aug. 24 1 12 0 14 13 279 67. 2 7 4 5.1 Utiae: 26s e od ones 54 MC Os ae 0 7 3 10 10 109 | 44.9 a lr Ry? UR 27___.| Aug. 29 |} Aug. 29 0 4 3 6 7 98 | 43.9 ! U Oe os CLBH 28_.__| Aug. 30} Aug. 30 1 9 1 12 11 227 43.6 7 5 5.0 77.0 29____| Sept. 4} Sept. 4 0 7 1 8 8 YN PRO 6 5y |) 483 77.5 30___.| Sept. 5 | Sept. 5 0 9 2 jul 11 210 16. 2 5 5 5. 0 79. 1 PVC EAL Cup penne aT ae (0) 7/ 6.3 Wag 8.9 SET 2a 57.8 Teal cial (Pe afl ie eqn DL 1 The average of the incubation records of all eggs laid by one female. 2 The temperatures recorded in this table were obtained from hygrothermograph records in the laboratory at Richmond, Va. INCUBATION PERIOD The records of development of 30 eggs laid in June and July, 1931 (Table 1), gave the following incubation periods: Maximum, 7 days; minimum, 3 days; average, 4.8 days. For the eggs laid in August, 1931 (Table 2), the incubation periods were as follows: Maximum, 6 days; minimum, 4 days; average, 5.3 days. The length of the hatch- ing period is greatly influenced by temperature. For example, the maximum period of 7 days (Table 1) occurred during the period June 23 to 30, when the mean average temperature was 75.1° F.; whereas the minimum period of 3 days (Table 1) occurred during the period July 7 to 10, when the mean average temperature was 81°. The longest incubation period observed in the laboratory was 17 days, in November, 1931, when the mean average temperature was about 5.95. As shown in Table 3, the incubation periods of all hatched eggs ranged from 3 to 9 days, the average being 4.5 to 7.1 days. Obser- vations were made on all of the 3,820 eggs laid by 30 females. 10 CIRCULAR 269, U. 8. DEPT. OF AGRICULTURE LARVAL PERIOD The developmental periods of larvae reared on flue-cured tobacco are given in Tables 1 and 2. The periods shown in Table 1 ranged from 29 to 72 days. These larvae showed an uneven rate of growth despite the fact that they were all provided with the same quality of tobacco and handled in a similar manner. Temperature is un- doubtedly a very vital factor in the growth of the larvae, although some individuals developed very slowly during hot summer weather. Larva No. 25 (Table 1) required 29 days to complete its growth, at a mean temperature of 81.2° F.; whereas larva No. 30 required 72 days, at a mean temperature of 75.3°. Owing to this uneven rate of growth, it is difficult to draw conclusions as to the effects of temperature. The larval periods of the individuals shown in Table 2 ranged from 35 to 54 days. Here again the rate of growth was uneven. For example, larva No. 4 (Table 2) required 35 days for the larval period, and larva No. 15 required 48 days. These larvae hatched on August 17 and were exposed to similar conditions in the laboratory. PUPAL PERIOD The pupal periods shown in Table 1 occurred during August and September, when summer temperatures prevailed, the average period being 11.3 days. The shortest period was 7 days, at a mean tempera- ture of 81.6° F. and the longest 19 days, at a mean temperature of 63.3°. The periods shown in Table 2 ranged from 12 days, at a mean temperature of 58.2°, to 24 days, at a mean temperature of 57°. The pupal periods shown in Table 2 occurred during October and Novem- ber, the average for the 30 pupae being 16.7 days. Most of the larvae pupated in loosely woven cocoons near the surface of the tobacco in which they were reared. EGG-TO-ADULT PERIOD There is a wide variation between the shortest and the longest egg- to-adult period, as shown in Tables 1 and 2. In Table 1 rearings Nos. 8, 12, and 13 completed the cycle in 45 days, at mean temperatures of 80°, 80°, and 80.2° F., respectively. Rearing No. 30 required 95 days to complete the cycle, at a mean temperature of 73.3°. In Table 2 rearings Nos. 4, 16, and 17 completed growth in 56 days, when the mean temperatures were 76.5°, 77°, and 77° F., respectively. The longest period in Table 2 (that required in rearing No. 28) was 81 days, at a mean temperature of 73.3°. The length of the egg-to- adult period is influenced by temperature. During hot weather most individuals have a more rapid growth. It was observed, however, that there are larvae upon which temperature appears to have little effect. As an illustration, rearing No. 30 (shown in Table 1) hatched July 22 but did not complete its cycle until October 21. DATA ON MATED MOTHS During July, August, and September, 1931, females of Ephestia elutella were mated on the day they emerged. Data concerning these moths are given in Table 3. All the females listed in Table 3 were mated on the date of their emergence. Each pair of moths was seg- regated in a glass vial and given a small piece of flue-cured tobacco leaf. The tobacco was replaced by a fresh piece every 24 hours, and the eggs laid during this interval were counted. It was observed that A PEST OF CURED TOBACCO, EPHESTIA ELUTELLA HUBNER 11 females preferred to oviposit on tobacco rather than on the glass vial, practically all the eggs laid being attached to the tobacco leaf. The daily lots of eggs were left on the tobacco leaf and examined every 24 hours for hatching. The hatched larvae were separated each day from the unhatched eggs and the number recorded. This pro- cedure was followed in handling all daily lots of eggs to obtain incuba- tion records. The unhatched eggs of each lot were examined for 10 days after the last hatch was recorded. By this time all unhatched eggs had become dried, shrunken, and distorted in shape, and it was apparent that further observations were unnecessary. The percentages of hatch for all eggs recorded in Table 3 ranged from 94.4 per cent to as low as 1.2 per cent, the average for the 3,820 eges being 57.8 per cent. The average of all the incubation periods (Table 3) was: Average maximum, 7.1 days; average minimum, 4.5 days. The mean average daily temperature during the period of longevity was calculated for each female and ranged from 73.3° to 84.5° F. The preoviposition periods ranged from less than a day to 3 days, the average being 0.7 day. The oviposition period ranged from 3 to 12 days, averaging 6.3 days; and the postoviposition period ranged from less than a day to 6 days, averaging 1.7 days. The longevity of female moths ranged from 5 to 13 days, the average being 8.7 days. In most instances high temperature reduces the length of life of females. However, there are exceptions, as shown in Table 3. For example, females Nos. 2 and 3 each lived for 5 days at a mean temperature of 84.2° F., while female No. 1 lived 11 days at a mean temperature of 84.5°. Laboratory records show that six females that emerged and mated in November had an average longevity of 14.6 days when the mean temperature was 59.2°. The total number of eggs laid ranged from 279 (laid by female No. 25) to 37 (laid by female No. 15), the average being 127.3. Owing to the variation in the number of eggs laid, no conclusions regarding the effects of temperature on egg laying can be drawn from these data. EGG LAYING The small grayish-white eggs of Ephestia elutella were ordinarily laid on the tobacco leaves. The eggs, when laid, are covered with a gluey coating, which usually attaches them to the leaves. The number of eggs laid during 24 hours was variable. The daily egg- laying records of the females listed in Table 3 are presented in Table 4. As shown in this table, the number of eggs laid during 24-hour periods by one female ranged from 0 to 90. Female No. 11 laid 90 eggs on August 10, when the temperature ranged from 91° to 78° F. More eggs were laid the second day after emergence than on any other day and most of the egg laying took place during the first five days of the life of each female. 1s CIRCULAR 269, U. S. DEPT. OF AGRICULTURE TaBLeE 4.—Record of deposition of eggs on flue-cured tobacco in the laboratory by 30 females of Ephestia elutella at Richmond, Va., 1931 Eggs laid days after emergence ! Total Date num- Female No. sepia | | | ber of emerge < = eggs FA Meee | ool) Sheet Real ee eid | ae a ib Meare Rebs od! ok roe July 28| 6 6E 27-1 10} 5 | 23 | 36) 12 |S) 8) 6 | ApoE ee 183 SP Bodie Fats 2 NW Wale poe oh” Reta July 31 | 81 28 bess: PA iy Olas espe ee awe abe ae a IE 126 dS pk BR ge a Soar We fee douse 2 G2 TESZ PSEA LE LO. Peso a a Pe tee fee eee 108 LR pS ehh Menke eae ile. Mien aie ee Aug. 62 2b EOS ES | OOK OF ae eh ee eee yee AE RENE pe Uae hbk ere BEA (7 tee | 8 43 tesee Gs av Ls Se |i Gee Oa ON: BOE ie Be ee eg fl et Bsa CE OE eae Aug. 4]}| 0 22, Fe2say 21 82 One eee] ee SE Fel ee [ad BEEN 76 7 Bas Se ie ESE ee Aus. & | 10 81 | 43 | 20 ae 2 | 20} 14} 14 7 6 0 0 211 SUE Weer s fee 2s ef See EI Aug. 61 0 77 (A2P AS” | EE Oc) On sae pe 3 ae ee fee 148 SL Ba ane eae et Eee Age) 2k G ST ee Wl yl Ee a) a fee ia oo) ie) LE ey er ee BEE 138 11) Se BEN pet OES Se eee ee Aug. 8! 0 AQ W351 SUL LQ ree Oat! Qe he bi he Gh Pee Fae ee 95 GBPS ne hue SB oa RS EE ee [See se 0 90 | 46 | Tf OO PO Seek Sc Peas a ee oe 144 | Ae ee ee ee eee Aug. 9}; 0 FL eS Sh hi pa era sa a 134 1130's 2 see pee wis SAN a ee. Cee Aug. 10} 1 Na ed ed V2 2) ol an ed ek GS a py BS ee) See Ee 120 Pura? RE Se Wee ae Aug. 11} 0 52 | 2A) “Sor Ooo ete eee 101 Ti, oan SF SaaS hae Aug. 12) Ot 0 1g] 25 | abe] 1 pes Sa es a 37 i (Feces Loe SS ae ache: Aen Cree Sa Oi. ae 0 O 2845) 63) P19 s4 bas (OL Gata ee Os pe eee 113 iy 220A a cae ce RR EES | Aug. 13} 0 © [a ae OP Behe Gy Sather eee et eae ay Tbs eho ee eee ae a oni Aug. 14} 0 CU Red Es trl fei We EPA a | a SA) (A ey 144 [Sete Eee We ie ea A ae Gee) (eet 14 HA bbee Label! Bo] Sy eal ACA Oba aes ee beens as 123 Fie | Sel snip et RN RR SPR BPS Re | Aug. 16 0 LAS rt tS 0 0 1 0 (1G) CRE Pa FRE San ESS 84 DNA PRO re) SOEs es i ee Aug. 19 | 4 SEASES Op Rb EPS OR et @ seit Rae eeepc ree 83 Dre Sieh pee Bre 5s, Meo LS ED pike PQ sass 0 38 1 § | 2b } 13 5 4iihy £@, | 22 Se eee 93 pee SER uae. rot Ue ae Aug. 20} 51 O07 am hed 2) 7-5 a a 2 He 4 eH a Ye |) a fe 126 T., EMDR LEE EN ge SE Aug. 21 | 0 43) Fone Dabs fod SORTA ee ee fe ee brie 99 POPC So SS re, oa ee ELS Aug. 24 0 80 | 51 | 42 |} 41 | 20} 14 POV AR 9| 2 4 1 279 Vine Uh eS ee Ae ee ee Pe) G ae | 11 AT |} FEN TOb DD a VON OF