Issued September 16, 1911. 
 
 U.S. DEPARTMENT OF AGRICULTURE, 
 
 BUREAD OF ENTOMOLOGY— CIRCULAR No. 142. 
 
 L. O. HOWARD. Enlomologial and Chief ol Bureau. 
 
 THE [NDIAN-MEAL MOTH 
 
 AND 
 
 "WEEVIL-OUT" PEANUTS. 
 
 C. IT. POPENOE, 
 
 Entomi * r<>i> and Stored Product Insect Tnvestig 
 
 • Mi; 11 
 
 WASHINGTON : GOVERNMENT PRINTINO OFFICE : 1911 
 
BUREAU OF ENTOMOLOGY. 
 
 L. O. Howard. Entomologist and Chief of Bureau. 
 
 C. \j. Marlatt, Entomologist and Acting Chief in Absence of chief. 
 
 R. S. Clifton. Executive Assistant. 
 
 W. F. Tastet. Chief Clerk. 
 
 F. H. Chittenden, in charge of truck crop and stored product insect investi- 
 gations. 
 A. D. Hopkins, in charge of forest insect investigations. 
 W. D. Hunter, in charge of southern field crop insect investigations. 
 F. M. Webster, in charge of cereal and forage insect investigations. 
 A. L. Quaintanci . in elm rge of deciduous fruit insect investigations. 
 E. F. Phillips, in charge of bee culture. 
 
 D. M. Rogers, in charge of preventing spread of moths, field work. 
 Rolla P. Currie. in charge of editorial work. 
 Mabel Colcobd, in charge of library. 
 
 Truck Crop and Stored Product Insect Investigations. 
 
 F. IT. Chittenden, in charge. 
 
 H. M. Russell, C. II. Popenoe, Wm. B. Parker, H. O. Mabsh, Tikis. II. .Tones, 
 
 M. M. High, Fred A. Johnston, entomological assistants. 
 I. J. Condit, collaborator in California. 
 P. T. Cole, collaborator in tidewater Virginia. 
 W. N. Ord, collaborator in Oregon. 
 Marion T. Van Horn, preparator. 
 
 
Circular No. 142. 
 
 United States Department of Agriculture, 
 
 BUREAU OF ENTOMOLOGY. 
 L. O. HOWARD, Entomologist and Chief of Bureau. 
 
 THE [NDIAN-MEAL MoTII AND "WEEVIL-CUT" PEANUTS. 
 
 Bj C. II. Popi \"- , 
 Entomological {.ssistont, Truck Crop and Stored Product Insect Investigations. 
 
 Until a few years ago the peanut had been considered as almost 
 immune from insecl injury, the plant being affected by few in 
 and the "nuts" being protected by their thick shells against most 
 of the usual bisect enemies of stored products. There are. it is 
 true, one or two species of beetles which by reason of their horny 
 jaws are able t<> cut readily through the woody tissue, but the injury 
 from any of these had b< en infinitesimal. 
 
 Since the advent of the mechanical thrasher or "peanut picker" 
 conditions have changed to a great degree. The machinery is by 
 no mean- perfect as yet, and the tendency of the operator to feed 
 the peanuts too quickly through the machine results in a large p< r- 
 centage of broken shells, and affords easy entrance to several of the 
 common stored-product pests. It is estimated that between 20 and 
 30 per cent <>l' the peanuts are injured in this manner, consequently 
 becoming "seconds,' 1 and in nearly every case becoming infested in 
 a short time a fter being stored. 
 
 Another source of injury to the shells of the peanuts, affording 
 ingress to insects, is the practice of piling the -ached nuts high in 
 
 l A1 a ii ting held June 14, 1911, at the Department of Agriculture, Washington, 
 
 D which was atl many prominent peanut dealers, chiefly from Norfolk, 
 
 Suffolk, and Portsmouth, Va., and from North and Smith Carolina, the question <>f how 
 
 .i " peanuts was discussed hy Mr. P writer, and an 
 
 menl waa reached t<> undertake the project of testing remedies tor peanuts In store. The 
 
 value of the peanut Industry for 1910 was estimated at $15,000, Assumu 
 
 Injury to . the loss to the 
 
 peanut | ve estima 0,( One 
 
 prominent dealei Injury, in t i * !• - - 
 
 ■.hen- a preliminary Investigation was made, Mr. Popenoe was assisted bj 
 Mr r. \ Johnston and bj Mr W. i: Beat tie, "t the Bureau "i Plant Industry. I 
 ii was owing to the servl ol Mr Beattle thai this investigation was begun. The i 
 panying circular is being Issued !>y request of the peanut !■'. if. Chittenden. 
 
INDIAN-MEAL MOTH AND WEEVIL-CUT PEANUTS. 
 
 the .storage warehouses. This makes it necessary for the workmen 
 to climb upon the stacks of sacked peanut-, thus breaking many 
 more, and increasing the percentage of infestation. 
 
 The insect chiefty concerned in the injury to stored peanuts is the 
 larva of a small dusky moth, commonly called the Indian-meal moth 
 (Plodia interpunctella Hbn.), a common and well-known pest, habit- 
 ually frequenting all places where foodstuffs and cereals may be 
 stored, and feeding, as its name would indicate, upon meal, flour. 
 and grain. It also attacks dried fruits, nuts, chocolate, and seeds. 
 Like other related species, it prefers darkness or semidarkness, 
 although at times seen abundantly in well-lighted storerooms. 1 
 
 DESCRIPTION OF STAGES. 
 
 The adult or moth, shown in the accompanying illustration 
 (fig. 1, a), is about one-half to three-fourths <d' an inch in expanse 
 
 of wings. The outer two- 
 thirds of the forewing is of a 
 reddish brown color with a 
 coppeiy luster, while the in- 
 ner third is whitish gray, giv- 
 ing the insect, while resting, 
 the appearance of being 
 cloaked. The hind wines are 
 dusky gray. The larva, 
 shown at c, d, and e. in the 
 figure, is dirty whitish, vary- 
 ing at times from greenish to 
 a decided pink cast. It is 
 about one-half of an inch in 
 length when mature. The pupa, shown at h, is about three-eighths of 
 an inch in length and light brown in color. It is inclosed in a 
 cylindrical silken cocoon or web, which may be mixed with frass. 
 The eggs are small and white, and arc deposited upon the food sub- 
 stance selected, either singly or in groups of three to a dozen. 
 
 LIFE HISTORY AM) HABITS. 
 
 The moths usually make their appearance in numbers, in Virginia, 
 
 by about the middle of June, and may be seen flying in the darker 
 portions of the storage houses or resting upon the sack- of peanut-. 
 
 'In addition to the Indian-meal moth, several other inserts are frequently found to 
 Injure peanuts in storage, These, in the order of their Importance, are as f..!iows : The 
 rust-red Hour beetle [THbolium naialc Fab.), the saw-toothed grain beetle (Silvanus 
 8urinamensi8 L.), the cadelle (Tenebroides mauritanicus L.), the ti^ moth (Ephestid 
 
 runt, II, i Walk.), and the Mediterranean Hour moth (Ephestia kuehniella Zell.). The 
 
 three former species are capable of cutting through the shells of peanuts, but rarely 
 occur in such numbers as t" !»■ injurious to them. They are amenable to the rem. 'dies 
 mentioned In this publication. 
 
 Pig. 1. — The Indian-meal moth (Plodia inter- 
 punciella) : a, Moth; b, chrysalis; c, cater 
 pillar: d, head: (, first abdominal segment 
 of caterpillar, more enlarged. (From Chit- 
 tenden i 
 
[NDIAN-MEAL MOTH \M> " w N T UTS. 6 
 
 Id unheated houses the first eggs are laid in March and April by 
 the moths just issuing from the pupal stage. At this time they are 
 comparatively scarce and are littli inter, when the 
 
 sive generations have been allowed to multiply, they become 
 very abundant, reaching their maximum in the Latter pari of Au- 
 gust. In heated rooms reproduction may be continued throughout 
 the winter. 
 
 Tin eggs hatch in about I da r deposition, and the larvae 
 
 at once begin the work of destruction. The larvi con- 
 
 sidered to Last about L8 days, varying according to weather condi- 
 tions. During this time the larva 1 crawl from one kernel to another, 
 feeding as the} goj and spinning a quantity of silken thread, which, 
 mixed with food particles and excrement, disfigures and injures the 
 material over which they craw 1. When the nuts have been attacked for 
 some time the entire mass re > a mat of webbing mixed with 
 
 powdered food material and I'm--. When fully mature the larvae 
 crawl about, seeking a place for puliation and spinning large quan- 
 tities of web as the] go, finally making, in cracks in tin flooring, 
 between bags, or in other dart places, cylindrical silken cocoons, in 
 which the larvae transform to the pupal stage. In hibernation the 
 larva remains throughout the winter in the cocoon, in a state of 
 quiescence, pupating early the following spring. 
 
 The pupal stage usually lasts from 5 to LO days before the issuance 
 oi' the mature insect, making the life cycle, under good conditions of 
 temperature, from 1 to 5 weeks and affording opportunity for from 
 A to 7 broods or generations oi larvae in one year. A -male 
 
 is capable of depositing from 300 lo 400 eggs, it may be seen that 
 the capacity for injury is c< nsiderab 
 
 \ \ ll l; u. I \l ■ M II -. 
 
 This in-eet has a number of natural enemies, the mosl prominent 
 being two hymenopterous parasites. Omorgus frumentarhiii Rond. 
 ami Uadrobracon hebetor A dim. These two form- do much to • 
 the multiplication of this and other similar pests. 
 
 II V] EDIA] Ml \-l R] S. 
 
 Although at first sight this insect seems to presenl a problem to the 
 r. its control i- by no mean- so difficult as might be sup] i 
 At leasl two effective method- of control arc applicable, namely, 
 heal and fumigation. 
 
 7 In h< <ii method of control. The treatment by heat, while new in 
 it- application to cut ire buildings, has during the past two years been 
 
 description of stages and notes on I ■ e are complied largely from thi 
 
 of Dr. V. II. Chittenden, published In Bull «, of the Burea oology, 
 
 i I Stati i leparl men! • ■' Igrlcul 
 
4 INDIAN-MEAL MOTH AND " WEEVIL-CUT" PEANUTS. 
 
 used very successfully, both in the control of the Indian-meal moth 
 and in that of the related Mediterranean flour moth. Both Prof. 
 G. A. Dean, of the Kansas Agricultural Experiment Station, and the 
 author have used this method in the control of the flour moth, and it 
 was used quite successfully by the latter in a peanut mill in Virginia. 
 It is. of course, only applicable to mills heated by steam. In the 
 proper application of this method the mill should lie thoroughly 
 piped and furnished with suitable radiators. Sufficient radiator sur- 
 face should be supplied to obtain a temperature of 120° to 125° F. 
 A few courses of 1^-ineh pipe placed along the side walls should 
 easily bring about the desired results. If a warm day in the summer 
 is selected and the steam is employed at a pressure of 75 to 100 
 pounds, only a small amount of radiator surface is needed. To 
 permit the most effective penetration of the heat, the bags of nuts 
 should be piled only a few feet deep, as experience has shown that 
 some time is required for the peanuts within the piles to be raised to 
 a uniform high temperature. The building should be closed tightly 
 and the temperature raised to 120° F., remaining at this point for at 
 least G hours. A longer time is advisable, as the penetration is 
 thereby increased. Bags of shelled stock are with difficulty heated to 
 the center without a long exposure, and although the larvae work 
 near the outside of the bags they may crawl to the center to escape 
 the great heat, which tends to make them much more active. 
 
 The temperature should not be raised a hove 125° F. in the case of 
 peanuts, as experiments have shown that a slight degree of blanching, 
 or slipping of the " skin," takes place in shelled Spanish nuts exposed 
 to such a heat. Virginia peanuts, being much le>s oily, are not 
 affected, while no injury whatever takes place in the case of unshelled 
 nuts. Germination is likewise unaffected, peanuts exposed ('. hours 
 to a temperature of 140° germinating better and more quickly than 
 those indicated. A temperature of 116° is fatal to insect lii'e in a 
 short time, larvae, pupae, and adults of the Indian-meal moth dying 
 in less than one-half hour, when exposed. 
 
 Fumigation. — In mid.- and storehouses where the beat method is 
 inapplicable, it may be necessary to fumigate with hydrocyanic-acid 
 gas. On dt< en nl of the extremely poisonous naturt of this gas > are 
 IS in < i ssary in its use, and. where careless Or ignorant help is em- 
 ployed, some danger might accrue through improper or careless 
 handling. Before the gas is applied the building should be tightly 
 closed; afterwards jars containing the requisite amount of diluted 
 sulphuric acid should be placed therein, and the paper bags contain- 
 ing the cyanid of potassium dropped into these jars, thus liberating 
 the gas iu the room. This gas is used extensively as a remedy for 
 flour-mill and household insect-, and where intelligently handled 
 
[NDIAN-MEAJ MOTH \.\ l> " W I i.\ 1 1 . ( i I PEANUTS. .1 
 
 gives excellent results. Full directions for its use are given in Cir- 
 cular 1 1- of this bureau. 3 
 
 Carbon bisulphid is also applicable as a fumigant, and is highly 
 effective, although its great inflammability and the possibility of its 
 explosion when ignited are ii isure against its use. 
 
 MEANS OF IMU . ENTK 'N '■■'■ I 111 P ICKEB. 
 
 In order to decrease the liability of peanuts to insect injury, the 
 factory should be kepi as free as po from an accumulation of 
 
 moths during the summer season. To this end, all cai fested 
 
 peanuts coming into the facto tild be fumig d before ent ranee. 
 
 The factories should be 30 constructed as to furnish as few hiding 
 places for the larvae and pupae as | . A modern reenforced 
 
 concreti structure >> ith concrete floors may lie. with proper attention. 
 kepi almost entirely free from the p< 
 
 The writer has seen large uumbers of the larvae hibernating 
 tween the two layers of a double floor that was apparently tight, 
 and with ease resisting ordinary efforts to diminish their numbers. 
 All cracks and ci innies large enough to hold a small quantity of 
 dust may also prove breeding places for the larvae. 
 
 Care in attending to the freedom of outgoing freight cars from 
 larvae will also he of value in controlling the injury due to insects. 
 An ordinary freighl car can be easily and safely fumigated at a 
 
 not to exceed $1, with cither hydrocyanic-acid gas or carl bisulphid. 
 
 Even a thorough cleaning of the car before reloading will he of 
 value in dot roving many insects brought in with the previous ship- 
 ment. 2 
 
 The storage rooms should he light and airy, and the peanuts 
 should not he piled so high that it i> necessary to climb about on the 
 bags in older to reach the top of the pile-. 'While some degree of 
 immunity may be reached by the storage of peanuts in large hulk. 
 still the incre imount of breakage from this method more than 
 
 balances tl fleets of the hulk storage. 
 
 The storage of peanuts in elevator bins holding several thousand 
 bushels each does not meet with this objection, as in such case the 
 inn- ire trampled hut little, ami the injury by insects i- limited al- 
 most entirely to the t<.p layer, rarely extending more than a foe! or 
 two helow ii,,- surfai e. 
 
 Ml ISURES "l PREVENTION BY THE GROWER. 
 
 [nfestation of peanuts by the Indian-meal moth frequently t 
 place in the storage sheds or ham- of the farmer or grower, where 
 
 'Circular 112, Bureau ol Enl - I States Department of Agriculture. 
 
 'Care should be taken that railroad agents deliver for peanut shipment only clean cars. 
 
UNIVERSITY OF FLORIDA 
 
 6 DIAN-MEAL MOTH AND " WEEVIj 
 
 3 1262 09216 5686 
 
 the nuts are held in reserve -and only sold as needed. Where the nuts 
 are held over the summer, the moths are allowed to breed freely, with 
 the result that many nuts that would otherwise escape infestation 
 are ruined. Storage in dark, dusty lofts or sheds also allows greater 
 increase of the insects by providing a suitable breeding place. Nuts 
 which have been held for several years by growers frequently show 
 large numbers of infested kernels. It is urged in this connection that 
 unless in exceptionally good condition with regard to broken shells. 
 no nuts should be held in the granary of the farmer later than the 
 it of June, at which time the injury by the first generation or 
 "brood" i- just beginning. When held later, without proper fumi- 
 gation and attention, the multiplication of the pest is unchecked, with 
 the result that the grade of the nuts is materially reduced. 
 
 Of primary importance is the proper selection and operation of 
 the peanut picker or thrasher. There are several types of this ma- 
 chine on the market, which with careful use may he depended upon 
 to break a minimum amount of the shells. The almost universal 
 cause of such injury is the practice of crowding the machines in 
 order to thrash a larger quantity of nuts in a short space of time. 
 This practice is reprehensible, as it is responsible for the large amount 
 of broken peanut shells found in machine-picked nuts. While more 
 profitable to the thrasher, its expediency seems doubtful, as the grade 
 of the tints is thereby reduced and the opportunity for infestation 
 increased, thus reducing the price obtained for the product. The pea- 
 nut packer will readily pay a higher price for an article in which he 
 can be assured of a maximum number of fancy nuts. It is therefore 
 suggested that proper attention be paid to the operation of the picker, 
 and that care be taken that the machine is not crowded. This will 
 result in much less breakage and so diminish the infestation that 
 there will be little need of further precaution in the matter of storage. 
 
 o