~ I~~ ~ 128 Iii ~ 1I111~ ~ lSi ~II~ Ij,iW 11,1.0 Ij,iliij w II:,j ... ~ ... ~ iii iii ~ ~ ~ ~ I.i ...... 1.1 ...... 111111.8 -
'"" 1.2: 111111.4 11111 1.6 "'" 1.25 111111.4 111111.6
MICROCOPY RESOLUTION TEST CHART MICROCOPY RESOLUTION TEST CHART N~TIONAL BURE.~U Of STANDAR~5-1963-A NATIONAL BUREAU or STANC·ARDS-1963-A D \.lCO~-\ Technical Bulletin No. 723 June 1940
UNITED,S'l'ATES DEPARTMENT OF AGRI(~liLT(JRE W4.~:p:INGTON, D. £.
Jliology' of the Seed -Corn Maggot in the ~ '~Coasta\ Plain of the South Atlantic States 1
By W.•J. R~!D, JR. _-:'Assistant entomologist, Division of Truck Crop and Garden Insect Investigatiom, Bureau of Entomology and Plant Quarantine 2
CONTENTS
Page Introducti"n...... 1 Biolot;iclli studies-Continued History apd di~t~iblltion ••••.•... _ _. ...• .. .. . 2 The egg...... 10 Systematlr pO
~
IXTRODUGnON
The seed-corn maggot 3 (Hylemya Ci{{Cl'Ul'l£ (Rone!..)) is the larva of a .fly that is widely distributed throughout the Temperate Zones. It is known to have an extensive range of food plants, among which are several important vegrfuble crops, such as potatoes, beans, spinach, cabbage, melons, and peas, and is thus highly injurious, The investigations reported in this bulletin were conducted from 1925 to 1935, inclusive, in Pamlico County and at Ch:1dboum, N. C., an~l in Charleston and Beaufort Counties, S. C. The immediate objective was to Jearn the habits of th'e insect so that a means of pre venting its injury to potato seed piece£ and to spinach seedlings might be developed. The investigations w,~re of great value in devising control measures for these crops, the ( etails of which have been pub lished separately (20, 21).4 It is pOSSIble tha.t the biological data re ported herein may be useful in formulating means of protecting other crops from attack by the seed-corn maggot.
I Submitted ror publication June 15, 1939. , Acknowledgements are due to W. A. Thomas ror hissllpervision or the stndies and his mluable ad"ice, to D. G. Hall for his descriptions and drawings or the variolls stages or the insects, to Clay G. HulT for his mi· uable sLlggestions, and to C. O. Rare ror his assistance in the preparation 01 rertain parts of the manuscript. 3 Order Diptera, ramily 1\[u~cidae• • Italic numbers in parentheses reler to Literature Cited. p. 41, 180895-40 1 2 TECHNICAL BL'LLETINi23, 1:. S. DEPT. OF AGRICL'LTURE
HISTORY AND DISTRIBUTION The insect now known in the United States and in most other English-speaking countries as the seed-corn maggot (1) has been given several other common names in economic literature. Among these have been the following: "deceiving wheat fly," in 1856 (5, p. 301) j "serd-corn flower-fly," in 1870 (30) j "anthomyia egg parasite," in 1877 (23, Rept. 9); "seed-corn fly," in 1882 (16, p.199); "bean fly," in 1896 (17, p.l11)j "bean maggot," in 1905 (31,p.123); and "spin ach bud worm," in 1932 (11). Hylemya cilic7'Ura has also been discussed in American economic literature under the names Phorbia, jusc1.ceps Zett., Anthomyia zeae Riley, Pegomyiajusciceps Zett., Ohol'tophilajusciceps Zett., Hylemyia deceptiva Fitch, Anthomyia augustifrons Meigen, Ohortophila cilic7'Ura Rond., Phorbia cilicrul'a Rond., and A.nthomyia radicum var catalopteni Riley. The seed-corn maggot occurs throughout the greater portion of the United States. Chittenden5 records that "it ranges through several life zones from Calluda to the Me~-icfln border and from the Atlantic to the Pacific, iIlllabiting all arable portions of North America." According to Parks, in his discussion of Schoene's article (27, p. 133), it occurs at altitudes as high flS 4,500 feet above sen level. The first record of its occurrence in North America apparently is that of Fitch (5), who in 1856 wrote that adults of Hylemyia deceptira, the deceiving wheat fly, were found in abundance upon the flowering heads of wheat during June of theprevious year. Riley (23, Rept.1), in 1869, recorded the insect under the name "seed-corn magaot, Anthomyia Zeae (Riley)," as attacking corn in New Jersey. Chittenden (4) stated that "the seed-corn maggot is f 'lery likely responsible for the damage attributed to the cabbage mqggot and to the onion maggot in the States south of New Jersey. The seed-corn maggot occUrs also in Alaska, Canada, Bermuda, South America, Europe, Asia, ~outh Africa, Ilnd the Hawaiian Xslands.
SYSTEMATIC POSITION 6 The seed-corn maggot (Hylemya cilicrura.), first described by Ron dani (26, p . .98) in the genus Ohortophila, has since been described a number of times. The synonymy has been given by Huckett(13,p. 24). Several authors have stated recently that some doubt e~-ists as to the validity of the name cilicrura. They advance the opinion that Hylemya, juscicf-ps (Zett.) (32. p. 15.52) represents an older name. In 1933 Ringdahl (24, p. 24) pI:Lced H. cilicrura (Ronel.) as a synonym of H. juscicep.s (Zett.). In c..)rrespondence ,\-ith the author, H. C. Huckett wrote on Jammry 2";", 1935, that the juscicep8 recorded by Malloch (18) is the samespecir-s described by Ringdahl (24) as HyLemya pilifemur. Huckctt (13, p. 25) previously had stated, "entil recently Hylemllia cilicura Rond. has heen confused ,,,-ith II. ju.sciceps Zett. According to Stein (1916) [(28, p. 167)j, however, cilicrura Rond. and fusciceps Zett. are two distinct species." , Unpublished notes . • Written by D. G. Hall from data compiled by author. BIOLOGY Q},' SEED-CORN MAGGOT IN SOUTH ATLANTIC STATES 3 The late J. M. Aldrich collected specimens of Hylemya jusciceps several years ago in Alaska. In con-espondencehe stated that it was obvious that two distinct species eJ..isted in North America, and, in his opinion, the Alaska specimens represented the Europeanjusciceps, and tile economic damages caused by the seed-corn maggot in the United States were due to H. cilicrura. Doubt will exist in the minds of many students of North American dipterology in regard to the use of several names of muscoid flies pro-. posed by older authors until type specimens of such species have been examined by competent specialists; but although it is possible that there are older names for the species herein called Hylemya cilicrura (Rondani), they are not accept.able until sufficient proof is given of their authenticity. Specimens of the species studied in the present investigations were determined by H. C. Huckett in 1925 and by J. M. Aldrich in 1929 as being the seed-corn maggot H. cilicrura (Rond.).
DESCRIPTIONS OF THE STAGES 7
THE ADULT
(Figs. 1-3) The genus described by Robineau-Desvoidy as Hylemya (25, p. 550) includes flies with the following characters: Head (fig. l).-Eyes bare, separated in the males rarely more than by the dis tance between the posterior ocelli; vibrissal angle and oral margin but slightly pro truding anteriorly at most when viewed in profile; hairs not extending on face; ?ntennae not conspicuously separated from each other at base, arista pubescent; cheeks narrow, the oral margin not constricted anteriorly by the approximation of the vibrissae in extent equal to or greater than the breadth of the cheek directly ventrad of the eyc. Thorax.-Gray pollinose, with three postsutural dorsocentral bristles; hypo pleura, pteropleura, and propleura bare; under surface of scutellum "ith fine, soft, erect hair; metascutellum absent. Legs.-Black; hind tibia of male with a series of hairs or setulae on the postero ventral surface; hind tibia of female with well-developed cruciate bristles. FIGURE I.-Head of adult female of Wings.-Hyaline; anal vein at least Hylemya cilicrura, lateral view. weakly extending to the wing margin; lower • calpyter not conspicuously protruding beyond the upper and subequal. The species Hylemya cilicrura may be characterized as follows: .Male.-Midfemur with posteroventral surface bare except for two or three al?ical setae: directed apicad; midtarsus without long hairs on dorsum; foretibia WIth strong curved postcroventral apicel bristle. which is usually blunt; midtibia without .!~croventral bristles; hind tibia with only one anteroventral apical bristle, j '.le position for the posteroventral bristle being filled by a series of fine spinulae; hind pulvillus equal to or smaller in size thaI! those of midleg or foreleg. The male genitalia (fig. 2) are unique. Female (fig. 3).-Parafacials gray pollinose, in profile not prominent, the breadth at base of antennae not equal to width of third antennal segment; pro 7 Prepared by D. O. Hall. 4 TECHNICAL BULLETIN 723, U. S. DEPT. OF AGRICULTURE
u\) c A
FIGURE 2.-Male genitalia of Hylemya ciUcrura: A, Rear view of forceps; B, left . latcral view of hypopygeal composite; C, fifth stcrnite.
r
FIGURE 3.-Adult fcmale of Hylemya cilicrura, XI6. BIOLOGY OF SEED-CORN :MAGGOT IX SOUTH ATLAXTIC STATES 5
boscis neither thickened nor highly polished; abdomen densely gray pollinose, with a trace of a dorsocentral vitta, the fifth tergum on disk with short oppressed setulae only, the marginal bristles normal; midtibia without an anteroventral bristle; hind tibia with a preapical setula on the posteroventral surface, and with a stout posteroventral apicad bristle, the preapical posteroventral bristle being replaced by a fringe of setulae. THE EGG (Fig. 4)
The egg of Hylemya cilicrura is of normal anthom~iine shape, being elongate ovoid, with the posterior end blunted. It is pearly wnite, and averages about 1 mm. in length. It is about three times as long as the average wic1th through the center. The chorion is reticulate, with numerous branching longitudinal ridges.
THE LARVA (Fig. 5) The larva of Hylemya cilicrllra may be briefly characterized us follows: Pearly white, of normal muscoid shape and appearance. Segments 12 in number including head, and of about equal length. Smooth, exceptfor scale-like posterior edges of rugose lines, which are confined to the cdges of the segmcnts. Ko posterior cavi ty, the posterior spiracles (ps) mountcd in tips of slight protuberances, separated from each other by a distance equal to thrcc timES the diameter of om. spiraclc. Anal opening lying ventrally between spiracles. Anal segment (fig. 5, E) armed on cach "ide of anal opening with a pair of small scalelike setae, and beyond these a longer and more heavily chitinized pair; ventrally, two smaller setae occupying much the same position on the segmEnt as do thc FIGURE 4..-Dorsal and lateral \'iews spiracles dorsally; latbrally, on edges of seg- of egg of IIylemya cilicrura; X 140. ment, three longer setae, these equidistant from one another; dorsally, two sctae directed anteriorly. Each spiracular plate rounded, ehitinized, and with three openings in the form of slits, except in the newly hatchcd larva and in the :;econd instar. Xumerous branched oral grooves (og) radiating toward the dorsal surface of the head from the oral opcning, wherc they unite to form a funncllike entrance into the oral aperture. Antcnnae (a) on each side of thc head near apex slightly longcr than greatest diameter. Maxii lary pal pus (mp) minute. Newly hatched larva.-Length about 0.7 111111. White, all segmental lines with restricted rugosity, the posterior edgts of which are brokcn into numcrous scale • like projections. Head segment ventrally with lines of scalelike spines radiating toward dorsal surface. ;\letapneustic, posterior spiracles with two cntrances each. BllccopharYllgeal apparatus weakly developed, ehitinized heavily only in mandibular hook, articulated by a long slender rod which is solidly attached to a weakly devcloped basal piece, paired and connected ciorsocentrally. Second instar.-Lcngth 3.0 to 4.5 IIIIll. Xo scalelike projections Oil cephalic segment. Bllccopharyngeal apparatus more heavily chitinized, articulated, equipped anteriorly with a pair of strong latEral hooks (lit) and attached together by means of a slllall median hypostomal "clerite bet\\"l'en hooks lind basal piece. Each plate deeply incised posteriorly to form a rodlike dorsal accessory piece; dorsal cornu in lateral view anteriorly drawn out. Posterior spiracles (fig.5, B) with two entrances. },fature laroa.-Length 5.0 to 7.0 mm. Gcneral form as shown in figure .'), A. Head with rathrr large antcnnae CD, a), and smallcr maxillary palpi (D, mp). Amphipnenstic, the anterior :;piracle:; (a.~) with six openings in elongated finger like processes. Larva of le:;s segmented appcarancc and stouter. Bucc('pharyn
.. -:I 6 1'ECliNICAL BULLETIN 723, U. S. DEPT. OF AGRICULTURE
T m I r.." ~#-+-i1-+' I) lr c
•.
FIGURE 5.-Larva of Hylemya cilicrura. A, Mature larva, X20: a, Antenna; as, anterior spiracle; ps, posterior spiracle. B, Posterior spiracle of second inster larva. C, Buccopharyngeal apparatus of mature larva, dorsal vicw: lh, Lateral hooks; bp, basal piece. D, Same lIS C but side view: og, Oral grQoves, mp, maxillary palpus; lr, longitudinal ridges. E. Last larval segment. P, Posterior spiracle of mature larva. BIOLOGY OF SEED-CORN MAGGOT IN SOUTH ATLANTIC STATES 7
genl apparatus (C and D) with strongly chitinized and well-developed basal piece (bp), the ventral surfaces of which have distinct longitudinal ridges (lr). Posterior spiracles (F) with three definite openings. The presence of distinct longitudinal ridges on the basal piece and accessory sclerites in the median ventral lares show that the larvae are of omnivorous food habits.
THE PUPA (Fig. 6) Length averaging about 5 mm., approximately three times as long as the greatest diameter. LigiJt reddish brown when first formed, growing darker before emergence of adult. Segmentation relatively distinct ouly in the anterior two or three segments. Spiracular plates (sp) essentially as in the mature larva, the "sun-ray" charllCters not apparent. Auterior spiracles (as) dark, the six fingers extend ing fanlike.
HOST PLA~TS AND OTHER LARVAL FOOD As already stated, the larvae of the seed corn maggot feed upon a wide range of substances, including both Ih~g and dead plant and animal life. Food preferences appeal' to be the sprouting seed and the FIGURE 6.-Pupa of llylemya seedlings or decaying parts of such plants as cilicrura, X20: as, Anterior beans, corn, peas, and potatoes. The known spiraclejsp, spiracular plate. food materials are given in the following list, those observed in the present studies being marked with an asterisk: Lilting Plants Alfalfa (Jfedicago sativa). Mustard (Brassica juncea). Artichoke (Cynara scolymus). Oak (acorns) (Quercus sp.). *Beans, snap, lima (Phaseolus spp.), Onion (Allium spp.). soybean (Soja max). Orange (Citrus sp.). Beets (Beta vulgaris). Pea (Pisum sativum). Brusilels sprouts (Bras.sica oleracea var. *Peach (seed and seedling) (Amygdalus gemmifera). persica). *CAbbage (Brassica oleracea). Peanut (Arachis hypogaea) . .. Cantaloup (Cucumis melo). *Potato (Solanum tuberosum). CarrGt (Dauclls caroia). Pumpkin (Cucurbita pepo). Cauliflower (Brassica oleracea var. Radish (Raphanys sativus). botrytis). Rhubarb (Rheum rhaponticum). *Chickweed (Alsine sp.). Rutabaga (Brallsica napobrasl:lica). Clover (Tnfolium spp.). Seakale (Crambe maritima). *Corn (Zea mays). Sida (Sida sp.). Cotton (GossllPium herbaceum). *Spinach (seed, seedlings, and buds Cucumber (Cucumis .~ativu8). above ground) (Spinacia oleracea). Garlic (Allium 8Utivum). Squash (C1lcurbita maxima). Hemp (Cannabis sp.). Strawberry (Fragaria sp.). Iris (fris sp.). *Sweetpotato (fpomoea batatas). Kale (Brassica oleracea var. acephala). Tobacco (Nicotiana sp.). Kohlrabi (Bra8sica caulorapa). Tomato (LycopersiC1t1lL ellculentum). Larch (bark) (Larix sp.). Turnip (Brassica rapa). Lettuce (Lactuca sativa). Wheat (Triticum aestivum). :Muskmelon (Cucumis melo). 8 TECHXICAL BULLETIX 723, U. S. DEPT. OF AGRICULTURE
Dead Plant Tissue *Cottonseed meal (fertilizer). Larch bark. Living Animal Tissue Locust eggs. Dead Animal Tissue *Animal tankage (fertilizer). *Insects (adults of H. cilicrura that died *Fish meal and scrap (fertilizer). and lay on top of soil in the cages). Howard (12) states that the species was reared from human excre ment at Washington, D.O., in June 1900. If food is scarce during the larval stage, the pupae and adults are likely to be undersized. Such flies were often taken in field traps. I BIOL0GtCAL STUDIES The author has seen no complete account in American literature of ) the habits of the seed-corn maggot tlu:oughout the year in anyone area. The most detaHed published information on the biology of the species ~ in North America is apparently that of Hawley (10), who discussed t.he insect as a pest of field beans in New York. Leach (15), in his account of the relation of the insect to the blackleg disease of potatoes in ::\Jinnesota, discusses briefl:y the habits of the species in that State. In 1931 Rekatch ~~2) published a rather complete accotmt of the biology of the seed-corn maggot in Transcaucasia. During the period 1930-34 Ha.rulmwa, Talmto, and Kumashira (6, 7,8,9) described in detail the habits of the seed-corn maggot in Japan.
REARING METHODS During the course of the investigations reported herein, biological studies of the seed-com maggot were concluetecl under natural field conditions, in the insectary, and uncler controlled laboratory conch tions. Rearing of the species under caged coilClitions was not partic ularly difficult. except for the rarity of mating under these conditions. Only a few fertile eggs, approxima.tely 200, were obtained from females that had been caged from emergence. Fertile eggs could be obtained in the Carolinas throughout the greater part of the year from adults trapped in the fields. Adults 'were readily taken in manufactured, 5 by 6-inch, dome-shaped flytraps and in larger 12- by 12- by 12-inch ... traps constructed according to the specifications of Bi'>hopp (2). The field-trapped adults were caged in the insectary or lubonitory in the type of cage illustrated in figure 7. .. The base of this ca,ge consisted of a, tin or enameled haking pan or a, sha,llow earthen pot pltrtly fillrcl ',"ith a, dark-eolored snndy loam soil sifted free of large pa,rtie1es. Sueh ma,terials as spt·outing lH'a,ns or organic fertilizer ingredients were mixed into the upper in('b of soil to induce egg laying. A sponge in a smull, partly-filled aI'rninum " dish sunk in the soil supplied sweetened wa.ter for the flies in the (,lIge. A tw-ig bem·ing fresh flowers on which the a,dults were known to [ped was kept in the ca,ge, the cut end insprteci in a, small glass yinl of wnter pushed into the soil. The twig was held in place with a, plug of cot ton which also served to preyent the flies from g'ptting into tIl(' water. A cylinder of 16-mesh 'wire screen topped 'with cheesecloth formed the upper part of the cage. These cylinders ranger! in height from 1 mOLOGY OF SEED-CORN l\IAGGOT IX SOUTH ATLANTIC STATES 9 to 4 inches and in diameter fl'om 6 to 12 inches, depending on the num ber of flies to be caged. Best results were obtained flulll the lower type of cages, as n low top kept the flies neurer the soil and the food. The cheesecloth co,-ers were held in plnce with cotton twine or with rubber bands and were replnced frequently. Because of their positivel~- phototmpic reaction the udults could be handled in the cuges without great difficulty. This wus especially true if the work was done in a room with one source of light. ~When the top of the cuge was held toward the source of light, the mnjority of the flies remained on the cheesecloth cover. The occnsional escnped specimen would ulways fly to the windowpnne or screen, where it could be captured by plndng a gluss yial ovel' the fly and slipping a paper card between the mouth of the vial and the window co,'ering, After the flies were introduced into the top of the cage the cylinder wus pressed into the soil npproximutely one-fourth to one-half of itn inch and held in plnce with twine. A f('w drops of wMer, sweetened
.A FIGURE 7.-Cage llsed ill rearill~ work with the seed-corn maggot: A, Base of enge, showing sponge and flowers; B, cage with the top in position. with sucrose, aud of white of egg were pinced on the cage CO\'er8 dU.ily. Othcr types of cages llsed did not give. so satisfactory l·eslllt",. Eggs were deposited fredy by the field-colleeted ndults in the soil near sprouting beans or sueh orgnnic nULteriaJs as fish mellI, cotton seed meal, 01' animnl tunkuge. The eggs wer(' remo,"cd from th(' soil with a small camel's-hnir brush after being exposed by probing tli(' soil with il dissecting Il('edle. During the incllbiLtion period the eggs were k('pt 011 moist, IInrk-colo1'('(} blotting paper in 1- and :~-OUllce sake tins. Lnborntory cages for In1'n1(, !lnd pupnrin~ consisted of either Petri dishes or }~- to I-pint wnxed-paper icc-('reall1 cups, or l-qunrt to largel'-sized glass or metnl con tnillers. Enrthen pots of \"ilri ous sizes sunk in tothe soil were uSNl for ~field eng('s. Pi('ces of cheese cloth 01' muslin held in plnce with rubher ban 1snS9.1-4Q--~ ~ 10 TECH}"TICAL BULLETINi23, 1:. S. DEPT. OF AGRICULTURE larval food. This was confirmed by the associated work of Huff (14, p. 630), who wrote: From the results obtained in these experiments it seems necessary to conclude that the prEsenct' of bacteria, per se, is not essential to the development and pupa tion of the larvae of Hylemyia cilicrura. It seems permissible to conclude also that in the nutrition of the larvae of this species, the bacteria by their action on the medium sometimes play the role of preparing a suitable substratum for growth of the larva. Itseems permissible to conclude also that the substanct's essential to the growth of these larvae are present in bacteria-free, growing seedlings of beans and some other seeds. Although the flies of this species are active and excitn ble at orcli nary temperu.tures, they are so strongly phototropic that they fre quently remain in the top of the cage until death, apparently without having gone to other parts of the cage for water or food. Different met·hods of rearing were tested in the effort to obtain records of ovi position and Jongevity of individual specimens. After many failures to get an appreciable number of females to live through the preovi pm;itiol1 peried and to obtain fertile eggs from those confined since emergence in the ordinary type of insect cage, other types of cages were devised. Even though repeated efforts were made throughout the period of the studies to determine when and where mating occurred, only three cases were observed. As there was a possibility that mating may begin during flight, large numbers of adults emerging at known dates were liberated in large outdoor cages immediately after emergence. The cages were 5 by 5 by 7 feet and constructed of 16-mesh screen wire over a wooden frame and with a door in one side. The cages were located over partly sodded and partly cultivated areas, and potato seed pieces, sprouting beans, and organic fertilizer materials were placed in the cultivated soil. Fresh flowers on which the adults were kno'W-u to feed were kept in the cage, and sweetened water and egg white were placed on the top and sides of the cage three times daily. After remaining in this large cage until mating was observed or until near the end of the preoviposition period, the mating pairs, or the remaining females, were isolated ''lith one or mOl'e males in a small, low cage (fig. 7). Best results were obtained from cages 1 inch high, even though it was difficult to prevent the flies from escaping when the tops of such cages were lifted to remove the eggs. In other respects the cage used for isolating individual pairs was the same as that used for confining field-trapped adults. It was found that mat ing was more apt to occur-if it had not taken place in the larger cages-when two or three males were caged with each female, since the males do not live so long or tolerate confinement sowell as the females. In spite of many efforts to rear adults in captivity, in only four instances were complete records of fertilized females obtained. Apparently other workers have been unsuccessful in obtaining fertile eggs from adults of FIylemya cilicrura that have been kept in continu ous captivity. THE EGG INCUBATION PERIOD The incubation period varies with the temperature. Based on the results of the incubation studies sho\V1l in table 1, the mean period of this stage ranges in length from 1 to 8 ..5 clays at meun temperatures • BIOLOGY OF SEED-CORN MAGGOT IN SOUTH ATLANTIC STATES 11 ranging from 83.7° to 42.5° F., respectively. During January, E'eb~ ruary, and March, the season in which the insect is injurious to potato seed pieces in the coastal areas of the South Atlantic States, the incu bation period in 1926 lasted from 4.9 to 8.5 days, with mean air tem peratures· of 56.9° to 42.5", respectively. The incubation periods of individual eggs ranged for the entire period covered by the table from 1 to 11 days. TABLE I.-Incubation periods of eggs of the seed-corn maggot caged in the ground at Cash Corner and Chadbourn, N. C., 1925-27 lncubation Mean period air Eggs deposited Eggs hatched ---;----1 tem Dura- Weight pera tion ed menn ture ------.---1------·-;---,;------ , Num- Num· Per a OF. _-\pr. 17 __•______19f5 __ ber Apr. 19______1. fS _ ber cent Dav& Dav& Apr. 20______12 Apr. Zi..______12 100.0 2 2.0 72.8 May 1. ______24 May 4.. ______• ___ _ 24 100.0 3 3.0 67.S ?fay 14 ______21 May 17 • ______20 95.2 3 3.0 61.0 May 15______11 __. __ do______•______. 11 100.0 3 3.0 iO.6 31 31 100.0 2 2.0 72. 0 Ml\Y 1~ ______M>lY 20..______June 5______17 Juun 7______17 100.0 2 2.0 63.9 June 6 ______48 June 7-8______39 81.2 2 2.0 77.9 June 8..______.2 68 94,4 1-2 1.01 78. 1 20 June 9-10______20 100.0 1-2 1.5 78.5 Juni! 2'5 ___ ... ______.. ______June 29-30__ .______June 30______127 July 1-2______125 98.4 1-2 1.1i8 75.8 July L ______fi4 July 2______62 00.9 1-2 1.24 81.2 31 26 8.1.9 1 1.0 82.1 July 2 1______July 3______Sppt.22. ______56 52 92.8 1 1.0 8.1.7 i7 Sept 23 ______..______... ___ _ 65 1 1.0 72. 1 Sept. 23 ______55 Sept. 24-25______• ___ _ &U 53 Q6.4 1-2 1.01 7~.2 Sept. 24 ______7 Sept 25-26 ______7 100.0 1-2 1.5 ;2.8 Sept. 2; ______20 Rept. 26-27 ______20 ]00.0 1-2 1.5 72.1 Sept. 26 ______14 Sept. 27-28 ______14 100.0 1-2 1.5 72.9 &>pt. 23 ______23 Sept. 29-30 ______]0 33 Oct. 1.______43••5 1-2 ].5 72.2 Sept.2!l______22 66.7 2 2.0 70.1 Sppt.30. ______48 Oct. 2______100.0 2.0 69.6 Nov. 6______22 Nov. 9 ..______48 2 14 6."l.6 3 3.0 58.3 Nov. 14-15______61 Nov. 17-18______50 82.0 3-4 3.5 48.8 Nov. ]8_____ . ______34 Nov. 23-25______22 64.7 5-7 5.67 44.4 Dec. 13______100 Dec. 19-20..______76 76.0 6-7 6.80 44.9 19£6 19£6 Jan. 18______57 JRn. 22-26______Jan. 19______17 Jan. 23-28______49 86.0 4-8 4.87 45'5 Jan. 20______19 Jan. 27-31. ______16 94.1 4-9 6.00 44. 7 Jan. !!l ______19 100.0 7-11 7.52 44. 5 ]2 JaD. 29-30 ______12 100.0 8-fI 8.5 42. Feb. $ ______17 Mar. 6-7. ______13 17 100.0 8-9 8.47 45.8 Mar. 2•• ______Mar. 10______13 100.0 8 8.00 43.0 Mar. 31. ______16 Apr. 6..______5______]6 ]00.0 6 6.00 56.9 Apr. 105 I Apr. 8-9______3.34 6-1.0 Apr. 7______49 9 ______96 91.4 3-4 Apr. 49 100.0 2 2.00 64.5 Apr. I1. ______49 Apr. 13-14.. ______36 73.5 2-3 2.550.6 May 19______21 1'.lay 22-23 ______• ______19 po. 7 3-4 3.05 66.4 May 26-27 ______fji 1>lay 28.....______9 June 21______.. no £"8.4 1-2 2. 10 71. i June 21.______9 100.0 1 1.00 7'.8 19£7 19£7 Mar. 20______~9 Mill'. 22-:13 ______Mar. 21.. ..______61 IMar. 24 .. ______Mar. 31. .______27 Apr. 2...______Total or averagc .... l.illo ______/ 1 From July 2 tQ Sept. 20 no fertile cl(gs were obtained. , PerC'.!ntage based on total. The eggs used in this series of tests were placed on moistened blot ting paper in salve tins kept in small wooden boxes sunk approximately one-fourth to one-half of an inch below the level of the soil floor of the insectary. They were placed where sunlight would reach the soil above the boxes. This location approximated the moisture and tem perature conditions of the natural habitat during the egg stage and yet made frequent and accurate observations possible. 12 TECHNICAL BULLETIN 723, U. S. DEPT. OF AGRICULTURE To determine whether eggs can hatch under the extremes of tem perature and moisture to which they might be subjected under field conditions, eggs were caged under various conditions and in different locations other than in the field. The results of these studies, as detailed in table 2, indicate that eggs of Hylemya cilicrura fire rather lutrdy. They can hatch in air-dried soil and on saturated blotting p!1per, but not on dry blotting paper, which evidently had a desiccat ing effect. They will hatch at temperatures as low as 40° to 45° F. .( and as high as 95°, but only fl· small percentage hatched under open field soil conditions occmring late in April and early in May when the temperature of their habitat ranged from 75° to 107°. Since the eggs apparently do not hatch when subjected to temperatures of 100° or above, it can be readily understood why the breeding of the species is reduced to a minimum during the summer months, when temperatures at the soil surface often equal and frequently exceed 100°. TABLE 2.-Fiab-ilit.y and 'inC11bation periods of eggs of the seed-corn maggot caged 111lder variO'liS cond'itians, with the various lots 0/ egg.s arranged in order of the asce'nding mean iemperatl1res to which they were subjected, Charleston, S. C., 1930-35 Incnbation ! period ll\[~an tern· I Eggs deposited' Eggs hatched Location nnd conditions I pcr· Dura· Weightedl ature 3 lion mean ------.1------,---.1------,------INumber Nnmbuiperf'n'! Days DaY8 i 'P. Refrigerato!..•••._._.__ ._._.•. ~[ar. 6. 1935._,;..._•.. _1 120 ~ I 96.017-14 8.6 ~1H5 Laboratory room .. _._ ...._.._. ~ p. m .• Frb. _4. 1932... ,9 .0 !H.9 3-5 4.04 58.1 Insrctary.outdoors__ •..______Mar. 7.1935""'-"""1', 100 98! 98.0 4-6 4.5 .'m.1 Soil in field. 2-3 inches deep'_'j Nov. 10, 193~ ..-..- •.-. li9 H31 96.0 3-~ 4.3 61.0 Insectary.outdoors.._. _____ ... Mar. 26, 1930...... , ,0 64, 91.4 3-0 3.1 62.4 Laboratory room.•.....•.•.•. 4 p. m., Fch. 1I. 1932"11 119 115 I 96.6 2--1 2.39 65.2 DO •• ···-··--··••·-··.····.i 4 p. m, Frb. 10,1932.. 100 94 i 94.0 2·3 2.45 67.3 Incubator._._____...... ~. [ar. 6. 1935...... 100 94 t 91.0' 2-5 ~ 19 70.0 Insectary. outdoors...... __ .••J Aug. 25. 1930 •• _...... 10 7 I 70.0 12 2.0 70.4 Shaded ledgeof6-root ditch•.•f May 17. 1930...... 1 25 25 I 100.0 2-3 2.20 j(}-75 Do ,••••••..._...... •..••••\ May 18. 1930""""'1 10 0 I 0 I...... _...... 1 7n-75 Do....._••....•••...•._...... do...... 7 7 I 100.01 2-3 2.5 I 70...~5 Air·dried soil in insectary...... :-orayltl,I93O...... 10 9 90.0 1-2 1.5 72.0 Inscctary,outdoors••.••_••••••; .... Refrigerator and field ' .._...... l Mar. 22. 1935 .•.••_..••i 00 57: 95.0 (' &-7 1. fi (J.I i and I j I ... " I 67.8 'foial •...... ••••••••-L...... --.I,';ZOI----qn SUfi ;=1;.....··.·.'1== fl.. i , Caged on moist blotting paper in tin sol,e boxes, unlcss othcrwise stated. 2 Beginning of oviposiJion period, wbich usually ended 24 hours lat~r. 3 Of 2·hour periorls from initial o\'lpo,ition to last emergence. , On dry blotting paper. S Except at aboul 75° F. durin)! period 10 p. m. Aug. 25 to 9 a. m. Aug. 26. while clcctric cnrrent was off. G Rcmo\'ed on May 19 and placed on led~e of Moot ditch at temperatures of 70° to 75° }'. ; Kept in electrie·refrieerator frepzin'! unit at 25°F. rrom noon Mar. 23 to noon :-Olar. 25. then in refrigerator hydrator at 40° until noon Mar_ '1:l, tbcn in outdoor thermograph-shelter box until hatching. BIOLOGY OF SEED-COR~ ",[AGGOT I~ SOUTH ATLANTIC STATES 13 PERCENTAGE OF EGGS HATCHING Of the total of 1,610 eggs caged in the ground and listed in table 1, 1,439, or 89.4 percent, were found to have hatched. The number thot hatched of 1,120 eggs caged under various conditions (ta.ble 2) was 971, or 86.7 percent. HATCHING Eggs of llyltmya cilicrura usually retain their white appearance until the dnT of hatching. Thf' first e\Tidence that hatching is about to occur is a gradual clearing of the chorion as it chn.nges from white to translucent. In some ('ases it is possible to observe the movement of body fluids of the lan'a within through the eggshell. Eggs occa sionally have been noted to hatch, howe\·er, without such color change. During the process of hatching the egg covering splits in a straight line from the micropyle to approximately one-third the length of one side. The lar'.'!l moves its body from side to side, contmcting and expanding. "lIen about halfway out of the chorion it usually begins crnwling, dragging the shell and freeing itself from it if the shell adheres to the body. It was noted that the cV;'ering WitS more likely to stick to the young lu.rya when the eggs were kept under dry conditions prior to hatching. THE LARVA HABITS OF YOUNG LARVAE The young larvae Ill'£' llctive after emerging from the eggshell. TIleY llre inclined to be gregarious. Isoillted specimens nre frequently found, but usually several occur together, llnd as mllny as 100 lnrvlle have been observed in 11 mnss. They move about in senrch of food llnd begin feeding us soon as suitabl£' Inllterinl is located. Undel' llnt urnl conditions they do not trn yel far, since the eggs nre usunlly plncrd on or near a food supply. In gennml the movement of thr recently hatched Inrn1c is downward, probably becallse the eggs nre deposited nen}' the soil surface. The horizontul movcment on moist blotting paper of fivf' specimens 6 to 12 hours olel WiH" \\7atched during II period of 10 minutes. These t1'lweled at an nxemgr rnte of 0.4 inch per minute. A series of experiml'nts wrrr conducted to lenrn something of the vertical distflnce that llrwly hatched lal'\'ae can travel through the soil i:t srnrch of food. Thr cngrs consistrd of cfll'then pots covrred with cheesecloth nnd sunk to the soillrwl in the firld. Laryne of the first instnl' (and less tilll.n 2-1 hours old) wrre uscd, nnd these were plncrd just ben€'nth the surfncr of thr soil nnd dil'rctly abon' til(' food. Two typrs of soil \VNt' used in thl' cngrs. soil ns it occurrrd in the field, and that which WIlS dried llnd siftrd through a 16-mrsh wire sicve. Tnble 3 gives thc rc'>ults of thrse studies. I It was found that nlnrge proportion of 01P IfllTne SUI'v1Vl'd in nil the cngrs in which firld soil wns llsrd, c\'rl1 though thr major sourrc of food was ns much ns 3 inches derp. Lrss than 1 p('l'crnt cngeel in scrrrl1rd soil survived, en'n ",hrll plnced within 1 inch of food. Itwould appear thnt the firlel soil contnined rHO ugh food in the form of c1rcaying vege tation to support the insects un til the beans or the potntors could be reached, or rIse the screened soil brcnmc too compllct for mo\'emrnt of the larvne. 14 TECHNICAL BULLETIN 723, U. S. DEPT. OF AGRICULTURE TAllL]l 3.-Depth to which newly hatched larvae of the seed-corn maggot traveled in search of food, Chadbourn, N. C., 1925-27 ,J Food Cage Soli Larvae Adult~ Survival No. used D:~~~hRt emerged placed ------1----1------1------( Number C\'oue ______. ______Inche., • ______Number Percent 1 A.•.__ Field•. _. ___ •___ ._.__ ._._ 10 Noue o ~ A._.____ ._.dD_.______•••______10 Beau______Surface 10 100 3.A_.______••do______dD______0.5 4 A.._.. _____do______10 _____ do_____ . ______1.0 S 80 10 10 100 5 A •.••_____.do______. __ . ____ 10 _____do______2.0 5 50 _____ d~ ______.._____ •• 3.0 6 A.__•____._uo.______. ____ . _____• 10 9 90 1 B.____ Screened______. ____. Potato______.______1.0 2 R_.______do______•__ _ 20 o o 20 __ • __ do.______2. 0 o o 3 B •••____•__do ___ •______. ___ __ ._.do.______•______.__ 3.0 5 4 B._._. _____ do._. ______. ____ ._ 20 . ____ do___ •______.______4.0 1 20 _____do.__ •____ •__ ••______5.0 o o 5 B •••____ ._.dD..___ •___ •______20 o o . I C______do ••______•__ • 50 ____ Ao••..______. ______{ !~} i' } o o VALUE OF VARIOUS l\IATERIALS AS LARVAL FOOD Two series of small-scale tests were conducted at Chadbourn, N. C., to study the value of several materials as food for newly hatched larvae. Tin salve boxes were used as cages for the first series, and the speci mens were bred only through the larval stage. These tests were only indicative of what normally occurs in the field, for the type of cage used was far from ideal, and larval mortality was high. In a second series of cage tests to determine the food value of certain materials commonly found in the soil, earthen pots, which are more suitable con tainers than salve boxes, were used as cages. The results of these studies are shown in table 4. It will be noted that sprouting beans, poorly healed potato seed pieces, and fish meal were the most satisfactory of the materials tested as larval foods. TABLE 4.-Value of mrious materials as food for newly hatched larvae of the seed-corn maggot, Chadbourn,.lv. C., 1925-82 CB!'C tests LllrVRe II Matenal tested as food I Larvae survivin?, (number) I caged t to pupal stage Tested iu tin I . I I' sai~=.~~:"~: __ 1Nl£m"f~ Sprouting 'oylx>an •.•••_. __ .•.._____ ._._._•._.._•..•__ •• Numbe6i Perc~z:o L.-_-_-_-_-_-_-._._- •. i 2010 SH!!htly decayed potato. ______.•• __ ._•••_.••_._._ •• __ 4 I -10.0 l Fi~h lI!eal. rertililer mater in1. ____·_·_·______·_·_··1 s; 40.0 2.•••_____ •. 15 Decaym!! cabbQ!?" from field •• ____. ____ ..•____ ._•• __ ._. 4 , W.7 2.•___ ._.__ . 20 Commerri:ll fertilizer I mixture ______.' 0 I 0 L ______..I 10 Soli organir matter ' •.. ------.-----______._.___ •__ • 0 0 2______._ 10 Soil orl(na:c matter. dry.•_._. ______•___ •___ ._.___ •__ .__ 0 0 L______10 Soil orgauic matter. '"oistened______. ______._ 0 . 0 L ____ ._.__ • 10 ' Freshly cut potato, sounu______. _____ •______•• 0 'I 0 Tested in earth· enware pots: I L ______• 14 Potato seed plr~. rrpshlyrut,'al~ with fish meal.._____ ._ II I 7S.6 3. ______._ 55 Fish meal. fertilizer materlaL ______",__ •. _._., 29 I 52. 7 13______• 250 Potato 5Ced piece. poorly healed or decaying cut surface_ 112 I H. 8 3_____ ._____ 5'i Erans, sproutin!!____ •__ . ______. ______"______2~ I 41.S 3.•______• 48 Corn. sprouting __ ._._ .•__ •______•____ . __ ._._.______~_I 16.7 5______1·'i5 Potato se~d piece. frr~hly cut....____ ._ ••• _.. _••______1 1. ~ i ______._ 210 Potato S<'cd piece, with well·healed cut surfarcs.______0 I 0 4______70 Soil, field______..______•______._, 0 I L ______._ 50 i Fertili7.er. commercial ml~ture __ • __ •______·_·______·1 0 I , 50 percent of ammonia from or~anic sources. , As found in the field. . , Cut ~urrace did not heal properly. • BIOLOGY OF SEED-CORN MAGGOT IN SOUTH ATLANTIC STATES 15 CAGE TESTS OF PREFERENCES OF LARVAE OF DIFFERENT INSTARS FOR POTATO SEED PIECES WITH VARIOUS CONDITIONS OF CUT SURFACE A series of cage tests were conducted to determine the preferences of seed-corn maggot.s in different instal's for potato seed pieces having the various conditions of cut surface that nonnaUy occur under field conditions. Larvae that were considered to be representative of each of the three instars were used, and these were placeu either on or near seed pieces whose cut surfaces were either freshly cut or were poorly healed with the typical soft, brownish scum spot:;, or were decaying, or were well healed. From 10 to 50 larvae were placed in each cage. de pending on the number available. Earthen pots containing screened soil were used as cages and these were usually sunk in the soil of the in sectary floor or in the field. Results of these tests are indicated in table 5. TABLE 5.-Cage-test comparisons of potato seed pieces with different conditi01ls of cut surface as food for seed-corn maggot larvae of various ages, Chadbourn, N. C., and Charleston, S. C., February to May 1926-1932 Condition of potato seed I I Insects snrvi ... piece cut surface at time Cages speci., Inst!lI' Degrec of lar.. al feeding ing to pupal or larv"c were introduced mens g __~_!_n_<:ll_g_e______1_____I_.______I__U_d_U)...,t s_t8_e_ NILmber Number NumbtTipeTCI!1It 10 135 First.._..... None to slight•. _____ ._.... '2 1.5 Freshly cut...... { 7 90 Second...... Slight...•. __ .•...•••_..... I 4 4.4 7 85 'l'hird.....•• flllght to extensivc ••_•.._. t 56 65.9 Poorl~. healed with brown. { 14 300 First._••..••.•...do._._.•_..•.••••._••_. 130 t 43.3 ish lesions.' ~ 1~ ~~~a~:===:: ~~~~~si.~==::::::::::::==:: ~g g~: b 3 H First.•••.••_ Mo1erlltc to cltensive_.... 23 52.3 Decaying.•_._...... 1 10 Second_..... Moderate.•.••••._..•.•_.. 5 50.0 { 1 25 Third•.•__ •.•_.. _do.•..••••.•_.••_...... 6 24.0 I 10 170 First._....•., NC;;;6 ._••••• ___ ••••_••___• 0 0 Well healed ••• _....••...•_.. -I, 5 100 Second._ •._ Neue tc very slight._.__ •• • 26 26.0 5 100 Third•._._ ..••..odo••..•. _.•••••_...... • 93 93.0 I Only about one·fourth normal size. . 'Many specimens undersized, indicating that thcy had pupated without (urther feeding. 3 Seed pieces thet previously had been planted in the field or in cages while freshly cut. I AU specimens undersized, evidently pupating without further feeding. It was evident from these cage tests that the type of potato seed piece most suitable as larval food was that which had been placed in soil, while freshly cut and the e:ll.-posed surfaces of which, instead of be coming healed, had developed brownish lesions as a result of the nctiv ity of soil organisms. However, it was npparent that even this type of seed piece was not entirely satisffLCtory food for first-instal' larvae, • as less than one-half of the specimens survived thereon. Other obser vations indicated that decaying leafy vegetation, decomposing fertili zer materials, and sprouting or slightly decnyed beans were the type of food most suitable for first-ins tar lllrvae. Although the previously mentioned lesions were in reality a form of decay of the tuber tissues, they apparently caused no appreciable harm to the seed pieces other than to serve as entrance points for seed-corn maggots or other organ isms that destroyed some or all of the remaining portion of the set. Potato seed pieces that were regarded as decaying npparently were suitable as food, but to an extent that was limited by the stage of decay. In other words, partly decayed seed pieces appeared to he satisfactory food, but there seemed to be a point beyond which the stnge of decay rendered the tuber tissues unfit for larval fo d. 16 TECHXICM_ Bl:I.LETIX 7:!3, r. ::!. DEPT. OX' AGRICULTURE Potato seed pieces with freshly cut surfaces at the time the larvae were introduced in the cages were not suitable as food for firi3t- and second-instar larvae. Approximately two-thirds of the number of third-instal' larvne that were trnnsferred 1rom beans to freshly cut seed pieces survived, but many of the pupae were undersized, indicat ing that the larvae hnd fed very little after being transferred. Fur thermore, it was apparent that mn.ny of those seed pieces that were freshly cut at the time the larvae were introduced in the cages soon developed lesions on their cut surfaces fmd thereby bl;'rume satisfac torY food. Potato seed pieces with well healed (corked) cut surfaces were not suitable as food for any of the three brval instal's, the first-instal' specimens dying when provided with this type of food only and older specimens either dying or pupating after little or no further feeding. The results of these and later-described tests, together with field ob servations of the habits of the insect, led to experiments in coopemtion with the Bmeau of Plant Industry of the United States Depnrtment of Agriculture which resulted in the deYelopment of a means of pre\"Cnt ing injury to seed potatoes by the seed- com maggot through the suber ization (healing) of the cut surfaces of the seed pieces in adnlllce of their planting (121). EFFECT OF SOIL )IOISTlJRE O~ LARVAL DEYELOP)IE~T A series of cage tests were conducted to determine something of the influence of soil moi'>ture on larval development. These studies were made in the insectary at Chadhourn during June nll(l Jllly 19:!6, and the results are indicated in table G. The lnrvne were cnged in sandy loam soils with three different general gradntiolls of water content, hereinafter termed air-dried, moist, and wet. Soil dried on a shelf in the inseetfLry wns clnssed as nir-dried, thnJ which eontnined approxi mately the optimum amOllnt of water for pla1lt growth wns clnssed nil moist, nnd a soil snturnted with water \Vns termed wet. Dec:lying po tato seed pieces were furnished ns food. ~Ioist soil is n ppnren tly the most fllyomble for the larya('. Extremely dry or wet soils seem to pro .-ide unfiLyornble conditions. The preferred food of the species ron sists of germinating seed· or see(llings nnd of decilrin~ plilnt tissue. Such mnterinls would hardly be found in a dry soil nnd would dec,lY too rapidly to pro,ide continuous food in yery wet soils. TABLE fl.-Reslllts of cage tests on the effect of soil 1/10 ist 11 rl' OIl larval dCl'floplIlcnt of the seed-corn maggot, Chadbourn, S. C., June and July 1926 --~-l (' ,_ Lnr.nl Sun-in Sum/ICT Sumber ...YumhH P(rrrnt ~roist. __ . __ .~ __ ._ ._. 2 :1(' 'lfJ Ut). i ,\-ct..______.... __ 2 ;jU 1 ;i, '; Do__ ...... ___ ._ ...... _... '~". , 1m :1 :J.n A ir-dried ..__ ...... 2 :10 1\ I) The length of time spent hy the insert in its 1:11"\'01 stnge :-:('ems to depend largely on the nbundance of suitnble food lInd I)Il the wetlther. Tnble 7 indirates the rilte of lon-al growth under YflrioliS ("onditiol1s BIOLOGY OF SEED-CORN l\IAGGOT IN SOUTH ATLANTIC STATES 17 in the field, laboratory, and insectary, as determined in cage studies. The species evidently is able to develop at rather low temperatures and does not thrive at relatively high temperatures. The duration 8 of the larval stage ranged from 5 to 78 clays, at mean temperatures ranging from 100° t.o 40°-45° F., respectively. Optimum tempem tures appeared to be from 70° to 85°. Development was appreci ably retarded at t.emperatures below ?oo, although the mnggots did develop at constant temperatures rangmg from 40° to 45°. Compar atively few larvae survived when caged in earthen pots sunk in open fields during the period from May to October, especially when intro duced in the cr.ges near midday, or when caged in an incubator at temperatures of 95° and u1>ove. Under conditions existing in the field in the coastal area of the Carolinas during February, :March, und April-the period that the insect is injurious to potato seed pieces the. larval stage r~quired from 7 to 26 days, excluding the prepupal perlOd, during whiCh the Im'vae do not feed. TABLE 7.-lTiability and developmental period of larvae of the seed-corn maggot caged under various conditions, Chadbonrn, N. C., and Charleston S. C., 1925-85 , Larvae iiiT,en~th of Mean tern· I . 'I 1I:I"'al stage perature I Period 1--1-'-0-: Xaturc of site Loention :§j § = ,I ~_.__ ._. ___\» ; E! i IE l~ ~ 1 ~ ! No. pct~!'-~--I"------'Il;;;'~:-'D~-;;-;-F~'~F-:: Feb. 26-,\[ar. 13. 19~5.: l.'iO 93.3! Field ,.... . C'hnrle~toll. • •• 11-15 (l) ... 56. S ).[ar. 21-Apr. 15.19~6, 75 ~!.3. . do ...... 'j Chadbourn.. ""'121-2Ii (ll' 56.2 ).[ur. 25·Apr.S.1935. i 150 8-:.0 ..do...... C'hnrleston .-.-•• 7-14 8.U ...... t66.59 Apr. 14-28. 1930 ...... 1 50 52.0 . do...... do...._ ....112-15 (3) .• 78.7 Apr. 16-).[8r S. 1935"1 200 3.0 .do .... I' do...... 1()-19 13.3 69.19 Apr. 23-"fnr 7. 1929.. 75 14.7 clo '. • do "" ...... 11-15 (I) ..... 67.4 Mar 17-27. 1930 ..... 25 0 do..... Charle~ton. introduced ..... 77.67 at 2 p. m. (tcmvern· I ture 8S· F.) Mar 19-29.1930••_.__ 25 W.O I.. clo ...... Charleston.inlroduced 18-11 (1) .. i7.00 i nt 6 p. m. (tcmpera· June-Octooor' 1 tnre SI° F.) ~o,·.18-Dee.22.1925. 30 40.0 ....do ...... Chadbourn .... "'''130-31; e'l 46.8 """ D~~2tF. 192&-Jnn. 2\). 50 I 62.0 ... dO .... .I do ...• ,32-41 (3) 4!.2 ..... Jan.3-Feb. 16. 1926 •. 751 ill.3 Insectary ! .do _.. .•. • ,30-45 (ll 45.4 Jan. 18-Feb. 28,1926 25 92.0 ..do . do. ... ,30-42 (I) 4S.ti "'" Feb. 27-Mar. 24. 1932 35 100.0 ....do ... ,. Charrllc;oston.•• ""••••• '.' 1*_II:'r'_"6" 22.9 .,2.8 •.• r"eb. 28-Mar. 24. 1932 3.1 97.1 ... do ._ ...... 21.9 52.2 ..... Ml1r.I-28.1932 ..... 1;., 11.,.3 .do.. do ...... _ .20-28 2.1.1 52.1 •••. ).[nr. 3-21.1932...... 30 100.n • do ... do ...... 18-19 18.5 51.0 __ • ;\[nr.4-28.1932_..... 21 1IO.9! ...do .•. do ...... 22-25 23.3 52.4 .. _... July 13-22, 1927.._.... 10 SO.O t....do ...... : Chudbourn ••_•• __ .•• ('-10 (ll 75.7 .••• Sept. 11-21, 1927..... 14 1 (111.2' ...rln... ' . do "" .•. 8-11 (1) 76.6 ... Sept. 11-2.1. 1926"':'1 JO 93.3' ..do do - • 9-15! (l) 72.2 •• Feb. 14-2\far. 3.1930.. 700 9.1.7' rncuholor ., Chnrlcqlon .. ••..j7-11> I', n 7i 7()-75 'I' .. Mar. 28-Apr. 6. 1935._ 150 8-1.01 " •• do .... 1 do ...... ,5-9 6.53 8.1.0 .. May 11-16, 1930 .... 1 12 01. i I " ..do..•••.••J . do...... 6 (I) ~5.0 ..•• Apr. 19-27. 1930.. 50 46.0; •.do.... ) do...... , r,..g (ll 90.0 I .... Aug. 25-Sept. 1, 193(1. 56 1O.6i ...do...... i do ..... • ..·..1 ~-S; ('1) 195.0 I ... Oct.11-19.19:I9. • I 100 8.0 .... do...... , do ...... ; 1-9.[ () 00.0 I' .. . Apr. 17-Muy o. 193~ I I!)O 43.01 . do...... do ...... I()-IS 11.0 1 100.0 I ..••• A Dr. 19-)'lay 3. 193, r _9 1.5.0 . do...... , do...... ••19-14 10. () 100.0 I,•••_. Mnr.lo-).[uy9.1930·1 nO 50.0' Rerrigerator...i do .....,45-60 [ 52.7 1Il-l51 ...._ )I"r. 1I-2\[ny28. 193.5 ~~, &';.0 . do .....1 do... .:.:.:. ii2-7S ~140--15 1= T ont 1 or range 'I-'().',." '3-" .....; ...... I -•. -...•.•.-. ~I< -S •{fl.53-jl()-100 60.9 17f1..7I 56.&- I or 2·hour periods from hatching to last pupation. 2 In all field loentions tho in~ects were in earthen pots sunk to sollle'·el. l Hecords not so made as to pernllt their being weigbterL • No breeding observed under field conditions. ! From hatching until the formntion of the pnpariulD. thus excluding the prepupal period. tbe duration of which is described later in this bulletin. lS0895--4(}--3 18 TECID NUl\lBER AND DUHATION OF LAHVAL INSTARS Information concerning instal's of the larvae of Hylemya cilicl'ura was obtained by D. G. Han, with the assistance of the author, from two groups of larvae that developed during February, :March, and April of 1932 at Charleston. Approximately 150 larvae, hatched within a 24-hour period, were caged together in an enrthen pot sunk in moist sand and kept in an open porch of the laboratory. Potnto seed pieces, sprouting beans, and fish meal were supplied as food. Five to 10 larvae were killed immediately after hatching and at the end of each 24-hour period thereafter until pupation was wen underway. The larvae were killed in hot water, run successively through 70-, 85-, and 95-percent, and absolute alcohols, cleared in Hetherington's solution, and mounted in balsnm on glass slides. Grouping of laryne into apparent instal'S was accomplished according to the structmeof the buc cophnryngenl apparatus nnd posterior spimcles. Results of the studies are given in table 8. The larvae have three apparent instal' periods, according to the structure of the buccophnryngeal apparatus. At a mean temperatnreof 58.5°F. the average larvae molted on tbe third and fifth days after hatching during the 16-day developmental period. Those Ih.-ing at a mean temperature of 64.2° F. and having a 12-day larval period nlso apparently molted on the third and fifth days. TABLE 8.-!Yu,mber and length oj larval instars oj the seed-corn maggot based on the appearance 0/ the buccopharyngeal apparatus and posterior s]Jiracies, Charleston, S. C., 19.'J2 GROUP 1. IL\'I'C'I!ED r'En. 13. \rE.\:-J' 'rE:\[PERATURE FRO:\[ lL\l'C'Imr. TO PCPA'r!OX, 5S. 5° ~'. Specimens in each instnr based on BIOLOGY OF SEED-CORN :MAGGOT IN SOUTH ATLANTIC STATES 19 TABLE 8.-N1lmber and length of larval instars of the seed-corn maggot based on the appearance of the bllccopharyngeal apparatus and posterior spiracles, Charleston, S. C., 19S2-Continued. GUOUr 2. HATCHED MAR. 28. MEAN TEMPERATURE FUI)~r n.-I.'rClllNG TO l'UPATION, 64.2" F. Specimens in each instar based on Larval nge from Buccophar~'ngeal apparatus Posterior spiracles hatching (days) First MOlt'l 'rhird First Second Third In . I109~Molt·lsecond to ing to· . . ~folt·log to pupa· Instar ,second! iostar third IIlstur Instar IDstur third instar rlum ...... 1 ...... 3 ...... _.... _... ____ ...... __ ~.,.~_,, __ ~ 2 ____ ."" __ ...... :I ...... Age range (tIlIYS)···1 1}.3 ,~__~~5 i···· ..1 5-12! U-1 I 2-tl ) ..· ..···1 7-11 I·····..· PUPATfON After completing their feeding period the larvae usually leave the source of food and move about in search of a suitable place in which to pupate. This is particularly true when they have fed on potato seed pieces. Where the maggots had been feeding on substances that did not require their tunneling into the material, pupation has been ob served to have taken place without the specimens having moved. Pupation usually occurs i.n the soil near the scene of larval feeding. After locating a situation from which the adult will probably be able to reach the soil surface, the larva stops crawling and remains motion less except for an occasional rotation of its anterior end. In the pro cess of pupation the body of the larva becomes shorter and thicker. As the outer larval skin thickens to form the puparium, dark rings appear between each segment. When first formed the puparia are of about the same color as tbe mature larvae, but later they gradually change to It reddish brown with a metallic luster. No distinct pupal cell has been observed, but the soil around the ... puparia usually is slightly compacted. This ig probably due to the movements of the larvae just prior to pupation, After the formation of the puparium the insect passes through a prepupal condition before the true pupa nppeaI's. The length of time spent in thi.s condition by five specimens caged at a menn tempera ture of 62.3° F. was between 40 and 48 hours. Another group of five specimens had a prepupal period of between 32 und 63 hours at a menn temperature of 61.5°. Thus it would appcnr that during thc spring the length of the prcpupal period is apprm:imately 2 days. Like other stages of the insect, the prepupal period is probnbly pro longed at lower temperatures and shortened at higher temperatures. 20 TECH~IOAL BULLETIN 723, U. S. DEPT. OF "\GRlCULTURE THE PUPA LOCATION OF PUPARIA The depth itt which pupitt.ion occurs und~r typicul soil condit.ions in the Cn.l'olina Coastal Plain is indicnteJ in table 9. These dnta were obt.ained 0]) April 11, 1925, when the brood attucldng potato seed pieces was principally in the pupul stage, and represent the location of the puparin in 1 square yard of smface soil to a depth of 9 inches. A mechanical analysis of the soil showed it to consist of 70 percent of sand, 25 of silt;and 5 of clay. The soil was dark and eontained considerable decaying organic matter and many sprouting soybeans, thus providing ideal conditions for development of the seed-corn maggot. The weighted mean depth at which the pupae were found was approximately 2X inches. TABLE g.-Depth I of pupaUon of the .~eed-corn maggot in soil, Pamlico County, N. C., 1925 CUInn· )' \ I t Cumu· Depth orsoi! Pupa· Part of lative II Depth of soil Pupa. \ Part 0 lative layer (inches) rIa total portion' layer (inches) na Total portion \ ------~----- ' , . l Nllmber Perce:nt Percent 11'\ INllmber Percent IPercent Surface...... 2 4.082 4.082 ,3.0-3.5...... 4 8.1631 87.754 0-0.5...... 3 6.122 10.204, 3.5-4.0 ...... 2 4.082 91.836 0.5-1.0...... 3 6.122 16.326114.0-,4.5...... 3 6.122 I 97.958 I. 0-1. L...... 5 10.204 26.530 4.5-5.0...... • 0 .000 97.958 1.5-20...... II 22 449 48. 979 5. 0-5. 5...... I 2 0-11 ; 100.00 2.0-2.5...... _ II 22.449 -7'01..!"g28 1',1 5.5-9.0...... 0 .000 I· 100.00 2.5-3.0...... 4 8. 163 u 1 I Weighted according to the depth, to the nearest one--eighth of an inch, at which the individual sllCcimens. or groups thereof, were found, the mean depth was 2. 28 inchcs. EFFECT OF SOIL TYPE AND ~IO[STURE CONTENT ON DEPTH OF ?UPATION As indicated by the results of the lubol'lltory cnge tests giyen in table 10, pupation takes place deepel' in It sandy-loam soil than in those of the sandy or clay types, and also deeper in moist than in air-dried or wet soils of the sandy-loam type. These cage tests ulso indicated that a greater number of larvae were able to reach the pupal stage in It moist soil thDn in air-dried or wet. soils. No field studies along these lines werc practical, since the inyestigaticns were confined to areas of sundy-loam soils, the moisture {'ontent of whic11 was continually changing. TABLE lO.-EJect of soil texture and moisture content on depth of 1JUpation of the seed-corn maggot, Chadbourn, N. C., Afarch-.July, 1925 Larvae Depth of pupation Soil texture Moisture Jrlcht8 1.93 1.0 2.1 1.7 .60 BIOLOGY OF SEED-CORN l\rAGGOT IN SOUTH ATLANTIC STATES 21 PUPAL DEVELOP;\lENT The ntte of development and viability of pupae under field, insect ary, and controlled laboratory cOll~litioJls are shown in table 11. The ~ time periods arc measured from the formation of the pupfil'ium to adult emergence Q.t the soil surface, and thus include the duration of the prepupal condition. This was done beCtUISe it was not possible to determine without injuring the specimen just when the true pupa developed. Upon the basis of the limited number of det£'rminatiolls of the duration of the prepupal period, it would appenT that approxi. mtttely 2 days of the time included in the ]mpal pel'iods ill these tables really are u. llonfeeding portion of the In.rval developmental period. Under conditions that apPl'oximn.ted those existing in the field at Chadbourn amI Charleston, and at l·epresentntive periods dming the year, the pupal stage was found to last from 7 to 26 days, at mettn soil temperatures l'flngin!; from 83.7° to 53.7° F. The pupae of those IUTvue that nttack seed potatoes llsually Itreformecl during )'fal'ch and April, at \v11ich time the pupal stn.ge was found to r!lIlge from 7 to 18 duys. Under insectary conditions the length of the pupal stage was foumt also to be from 7 to 26 dttys at menn temperatures of from 83.7° to 54.1°. The records of those pupn.e caged under conclitions of approximately constant temperature inclicate that the pupal stage is capable of development iLt mther low or high tempemtures. At a temperature of 40°-45° the pupal stage r!wged from 36 to 126 days, and at 95°-100° the duration mngect from 7 to 9 days. Relatively few specimens survivecl temperatures above 90°, paTticularly when kept n.t these temperatures from the time of pupation. A moist soil uppurently was most suitable for pupal development, but indivicluals of the stage survived in air-dried soil, and in u. soil that approached saturation. TABLE ll.-Rate of development and l!'iability of pupae of the seed-,~orn maggot, North Carolina and South Carolina, 1925-85 UNDER APPROXIMATELY J;'rELD CONDITIONS 1 I Lenl!thn! Ipupal period • Pupa- ; 1- Mean Pupal period' Nature o( site Location: ria 'Adults emerged I _ tern· , ~. Igrtd 1 5 _,=:" ".: pera· . v - i \ 1 ~s IMe' .----: Num. \ Nltm.\ Per. 1-----1- ; l' ber beT \ cent 'Pay! P'IV! I OF. Feb. 23~"Iar. 21.] Field•••••..••.•••• " CharlestlJn,' 300, 292 'l1.3· 17-211 20.7 I 58.16 1935. I Feb. 25-1>[ar. 21, j._...dn._•..•..•...•i .•.•.dO••.••..: 150 i 63 42.0: 1!l-2,1 10.7: 59.73 M~r~517-29, 1935....' '.' rlo ..•••••..••.•J .... do ...... 46: 40 j 1000, 8-12 9.8: 6129 Mar.2h\pr.1O,1932••' •••do ••••••.••••••. Chadbourn.. 15 14 \ 93.3.15-17 16.1: 5..'\.5 Apr. 2-20. 1935.....·•'··--·do•.•..••••.••-•• ; Charleston.: 45 38: 8-1.4 JI-li! 15.7, 63.86 Apr. IS-May 1~1930 .._•••dO .•..•.••...•_••\._...dO...... 50. 43· 116.0 7-12 I 9.6. r,;.44 May 15-26, 1921 ___ .•I' .....do...... ___ Chadhourn.•, 10 1, 10.0 11 \11.0 '12.10 July 8-16, 1927 __ •..•.l.....do••••••••.•.•..•do...... 10 . 1 10.0 9 9.0 '75.11 July 11-21, 1930.--•••l Insectary and !leI!\'. Charleston .• ' 25 14 W.O 7-13 9 1 '8.171 July 21-30, 1927...... Field.••••••_..•.•.•, Chadhounl. 10, 0, 0 : •• __ ...... 77:00 , Pupae in earthen pOt sunk to soil le'1cl. Ca~es usually discarded aiter an interval of 10 days without further adult cmergence. The posslhility of B cltapnusc was not reco~nized prior to 1931. , From formation of the first puparium to emergence o( the last adult. 3 Soil temperatures at 2· to 3·inch depth at each 2·hour period from initial [Jupatipn to la.stemergencc, unless otherwise stated. • Air temperature. , Caged in earthen pot from July 11 to 16 (JO a. m.l in Insectary; pot then trsnsferrC(1 to open field and sunk to soil level. 22 TECHNICAL BULLETIN 723, U. S. DJ~PT. O:/)' AGRICULTURE TABLE 11.-71ate of dellelopment and viability of pupae of the seed-corn maggot, North Carolina and South Carolina, 1925-35-Continued CNDER APPROXIMNrELY FIELD CONDITIONS-Continued Length of pupal period I !':"""":""-'r--I Mean l'uPa· Pupal period Nature of site Location riu Adults emerged tern· l'8ged pera· ture 3 ----- N,un· Per· beT Mt1n.ber \ cent Days Davs of. Sept. 1-10, 1930..... 'Field...... , •••. Charleston 25 14 56.0 7-9 8.2 • 79.70 • Sept. 29-0ct. 15, ••••do...... Chadbourn. 17 52. 9 8-16 12.4 64.6 1930. Oct. 1-15. 1925.... .••..do•••.•.•••••••.. 25 60.0 10-14 12.5 • 66.92 ••••.do••••.•.! 1: \ OCL2&-Nov.13, 1925...... do...... •....<10••••••• 18 10 55.5 14-18 16.0 • 53.71 UNDER L' -:.rar. 20-Apr. 8. 1932.\ Insectary...... !Charleston. 15 15 too. 0 17-19 18.3 63.04 Mar. 21-Apr. 8. 1932 \.....do...... do...... 59 IiO 84. i 15-18 16.7 62.98 Mar. 22-Apr.1I.1032 'j' .....do...... "j __ .. do...... 23 18 78.3 18-20 18.2 f>3.18 May 14-27. 192i ...... do...... Chadbourn. 10 10 100.0 12-13 12~2 71.06 July &-17. 192L ...... do...... do...... 10 10 100.0 ~H1 9.9 75.34 July 11-25. 1930..... 1. ....do...... [ Charleston .. 25 25 100.0 8-14 9.5 8.1.67 July 20-30. 1~2i.. ... '1' ....do...... Chadbourn 10 G 60.0 0-10 9.1 77.05 SClit. 2-11.1930 ...... do ...... [ Chnrleston. 5 4 SO. 0 7-9 8.5 j 74.76 Sept. 15-25. 1930...... do..... __ ...... do...... 20 16 SO. 0 7-10 8.8 77.0; Sl'pt. 10-0ct.l, J927 ....do.. .•. .../ Chadbourn 13 II 84.6 0-12 10.3. 67.6; Sept. 29-0ct. H. I ....<10 .. " • do ..... 17 16 94.1 10-15 66.93 1925. '1 ... 12.8 t Oct. 1-15, J925...... do...... • do .... [.0 45 90,0 12-14 12. 9 66.92 Oct. 2o-Noy. 15.1.....do...... Charleston 25 2·1 96~ 0 li-26 21. 3 54.63 1930. J 3,1 Oct. 25-No,·. 16. j..... d(...... 1 Chadbourn.I 36 91.7 12-221 10. 4 ; 54.14 1925. i f e,\tDER!CONTROLLED cONlH'rroxS' , I Mar. 23-June H. R~frigerator land'}Charleston 25 16 ' 64.0 i7-S4 78.7 !~S 1932. Insectary.:" 75. 9 41.0 1\at:i2. 25-June J3. }....<10 ...... I.....dO...... 19 16 84.2 75-SO i;.3 and 75.6 Feb. 27-July3, 19:15 .. Rcfri~erator...... ·,I.....dO...... 25 13 52.0 3&-126 88.7 40-15! Apr. 13·l\rn~ 1.19~5 In a!r.drifd soill...... do.... .•. 100 861 86.0 12-18 14.6 69.2 Apr.13--:.ra~ 1.1935. In "etsolL...... ,.....dO...... :16 20 55.5 13-18 13.4 69.2 Feb. 28-l\lar. 16, Incubator I ...... do...... 20 15( is. 0 11-16 12.08 70-75 1935. i0-75 3 SO. 2 ;~~~~:~~:... ~~: ·~~·~:~:I~~~;:~;.·.~~:·I·~~~::~~·r~~1 : 895, ::~ ~~:: 11~:~ July 8-18.1925 ..... Moist soil...... do...... 10 90.0 7-10 8.4 SO. 2 July 8-J8. 1925...... Wet soil ...... do ...... :0 0 ! 0 ...... 80.2 May 14-24.1927..... InCUbator ...... 1 Charleston.. 10 9 90.0 9-10 \9.2 85 90 90 I 95 ~;ii.:S¥~~if~~~: :::~·~~::.::::::·:::::[JL:::::( ,,~ ~ ~:g ::~~~::~~~: 95 Ju y 10-/:. }~fi'2i:' ~::::g~::::::::::::::: :::::~~:::::. :: ~g 1~ 4~.O j 95 1930. to Oct. 27, .....do...... do...... !3 25 11 H.O .• _••. J ... . 100 JU\~~, 1927 ...... do...... <10.__.. 1/ JO 0 0 .. ':':9--j--8"';' 100 Apr. 3-1 I. 1935.... •....do...... 'j'" do...... tOO ; '7.0 ~ 95-100 Apr. 2-12, 1935...... do...... do...... 2.1 7 I 28.0 7-9 7.9 05-100 , ______--O______...:-__'--___• __..:...... _....;l...~._ ..__ , Air temprature. ~ • Pupae were caged in soil. I In electric refrigcrator at approximately 41° F. from pupation to 5 p. m., June 6, then kept in insectary untilllnnl adult emergence. , In enge in in:;(!ctary. , Thermostatically controlled electric o\'en. " Placed [n incubator within 18 hours alter first specimens pupated. II Placed In incubator within 12 hours after first specimens pupated. " Placed in incubator on July 16. alter being kept in insectary several dav~. • /l Placed in incubator on Oct. 21, after being kept in insectary several days.' mOLOGY OF SlmD-CORN l\IAGGOT IN SOUTH ATLANTIC Sl'ATES 23 THE ADULT ElIIERGE1~CE FROlll THE PUPARlUlIl As the pupa.! pNiod progresses the puparium grndually darkens, and before e:l1lergence the fly can sometimes be seen through the pupal covering. vVhen transformation to the adult stage is com pleted and the fly is ready to emOI'go, the nnterior end of the pupal case bursts by pressure of the ptilinuIll of the insect, Ilnd splits either lengthwise 01' laterally along the sutumI lines. The opening usually inciudes the first two or three segments of the pUparJUIll, and occa sionally the split portion breaks off !llong iL suture, leaving a circular or semicircular opening. The ndult leaves the pupiLriuUl through this opening find makes its wny to the soil surface with the aid of its ptilillum. This blndderlike stnwtu1'e, located on the helld of the insect between the eyes, is expanded and contl'l1cted, thus making an opening through the soi1. If the soil be suflicientiy moist, these openings remftin more or less intnct until thc soil is disturbed. Emer gence to the surfncc of the soil tak('s plncc only rilll'ing the night or very early in the mOl'lling. The l'l'ln.tiolt is evidently nl'gflth-ely gl'otl'opic and not entirely positin'ly phototropic, ns nclults eIllerge from soil in <,ages kl'pc in dl1rklless. Newly emer'gNI adults ure ueti\"e flnd miL)" be seen walking on the soil surface 01' climbing Oil vegetation eiLrl}T in the morning before theil' wings n1'C inflated. Theil' bodies !In' lighter ill {'Otol' [md nre softer than those of older 81){'eimells, Dnd the still partly expanded ptilinum mn.y bt:' Sl'en...FoUl· appnl'('ntly l'e('cntly emel'!!l'd specimens, which WNe obset'ved at about 7 1\. Ill., in Apl'it and l\Jny, hnd fully l'xpanded tlll'ir wings in 1 to 2 hours 111\U were able to fly within 3 hoUl's. On(' fly tht\t l'1llCl'gl'd in the refl'ig- erato1', in the morning, did not luwe its wings fully expanded until about 5 p. m. INFLUENCE ON ADULT ElIlERGENCE OF DEPTH OF PUPATION AND cmlPACTNESS OF SOIL As indicnted in tnble 12, adults are appnl'entt,Y able to reach the surface of fl snndy-loam soil froIll n depth as great as 7 inchl's, which is deeper tlUUl puparia were ever found in the field. There was no very marked difl'erenec in the relative number thnt readied tho surfnce from depths of 4 inches and less. The compnctness of a sandy-loam soil did not materially nfl'cct the percl'ntnge thnt l'lllergl'd from depths ns great as 4 inches. Adults emt:'rging from depths of .5 inches or more did not seem able to rcltch the surface as readily as those nel1rer the surface. Emergence took plnce about I day litter from the 5-inch depth as compnl'ed to a I-incb depth. It was al;;o found that adult" Wl're able to emerge from n depth of 3 inches in 11 clay soil, but no extellsive st,udies of the habits of the insect in cla,y soils were conducted, as wost of the soils of the South Atlantic Coastnj Plain arc of a sancly-Ionm type. 24 TECHNICAL BULLETIN 723, U. S. DEPT. OF AGRICULTURE T.\BLE 12.-Effect of depth of the puparia rtnd compactness of a sandy-loam soil upon adult emergence of the s~ed..com maggfJt, Pamlico County, N. C., April,. May, and July 1.925 I Period from pupation to adult emergence Depth of pupation I Soil condition Puparia 1------1 Adults emerging (Inches) Weighted Range mean Numbtr DaU3 IktU3 Nltm/ur Pm:tnt Surface••__ ••, ••__ •• ------•• ------20 11-31 15.6 Ii 85.0 20 11-22 15.9 18 90.0 O. L ______..._. ~,;;~;act~::::::::::::::::::: 20 11-22 14.3 20 100.0 1 0 {Loose. ______.••___ 20 11-22 15.6 11 55.0 · -...-••••--...... Compact....__ .•_...... 20 14-23 15.7 15 76.0 20 {Loose...__ ...... __ ...__.. 20 11-22 14.6 13 65.0 · .-.-.-..--...... Compact...__..__ ...... __ ... 20 11-22 15.1 12 60.0 20 11-]9 ]3.0 14 70.0 3.0--____ ••______._ .. fc~~~ac-C::::~::~~:~:::::: 20 11-20 ]3.2 17 85.0 40 {Loose_..___ ...______.._ 20 11-20 14.5 12 60.0 · -..------Compact...... ______... 20 11-25 13.2 16 80.0 50 {LOOSe_ ------..----..... --••• 20 12-19 14.7 9 45.0 20 11-20 13.1\ 6 30.0 6:0::~~:::::::::::::: ~~rl~a~mpacC:::::::::::: 20 8--10 9.0 11 M.O 7.0..._____ ' ..._____ • . _'" do...... _____ ---..._-.._. 20 7-10 8.7 15 75.0 I The tests at depths from 0 to 5 inches were made in April and May, those at 6 and 7 inches In July. HOVERING OVER OBJECTS The ttdults were frequen~ly seen hovering in the air above the plants upon whose flowers they fed, and over such objects in an open field as an automobile, a coat, lumber, or fertilizer bags. They eould be seen to dart about in every direction; and as high as they could be detected. At. times they would fly tmvard one another and then quickly go in another direction, Occasionally they alighted for a few minutes on the object over which they were hovering. When the object was moved slowly the flies would follow. On one occasion during January, 25 adults were captured with a net while they were hovering above an automobile parked in a field. AU the specimens proved to be males. ADULT FOOD Adults seek moisture and food soon after emerging. The flies were observed to feed upon the flowers of It number of plants and upon sev eral other materials during the course of the studIes. The substances fed upon and the period of the feeding observations were as follows: Flowers of- Ptrlod Chickweed ______January to March. Narcissus______February and December. Hl':kleberry______February. Strawberry______February and March. Plum______. ____ ------______February. Peach______February and March. Pear______Do. Chokecherry______Do. Apple______• ______March. Serviceberry______Do. Loblolly bay______Do. Cabbage, broccoli, and collards__ . ______April. OtherHen substances: egg______All months. Sweetened water______Do. Juices of freshly Cll t potato seed pieces.______February. BIOLOGY OF SEED-CORN MAGGOT IN SOUTH ATLANTIC STATES 25 ADULT ATrR..4.CTANTS Peterson (19) found that the flies were attracted by the odors com ing from several alcohols, particularly allyl alcohol, isopropyl alcohol, ethyl alcohol, and butylic alcohol, and odors from fermentation by yeasts when mixed with sweet substances such as honey, molasses, brown sugar, or corn sirup. Harukawa, Takato, and Kumashiro (8, p. 110) state: "Dried pupae of the silkworm and cotton-seed meal were found to possess a remarkable degree of attractiveness to the adult of the seed-corn maggot." TABLE 13.-Relative effectiveness of various materials used as baits in trap ping adults of the seed-corn maggot, Chadbourn, N. C., and Charleston, S. C., 1927-30 Traps Adults taken Material Aver Set- Total tings 1 Set Male Female Total' t~~~r day ------/------Numb" Number Numb" Number Numb" Numb" Fertilizer mL,ture, all-organic ammoniate , ______.... 29 a9 106 001 701 18.13 Fish meal'_..______132 338 658 2,811 3,654 10.81 Tankage and dried blood .______73 157 243 1,330 1,615 10.29 Fcrtilizer mixture, 5O-percent mineral and 5O-percent organic ammoniates, with common superphosphate ,_ 19 30 50 240 290 9.67 Fertilizer mhture, 5O-percent mineral and 5O-percent organic ammoniates, latter Irom castor-bean meal ,_ 19 25 34 100 194 7.76 Cottonsred meal'.....__ ._.... __ ..__ .....______125 267 277 1,249 1.544 5. 78 Fertilizer mixture, all·mineral , _____ ...... ____ ..__ __ 22 a1 25 109 134 4.32 l'.IollISSes, water, and isopropyl alcohol ...___ .._____.._ 39 919 ______47 182 .1 250 2.75 Orange, sllced ....___ ...... _____ ....___ • __ ..______2 2·f, 2.67 Sullate 01 ammonia ' ..__ ...... ______..______5 5 0 13 13 2.00 Banana, sliced______.._____ •______•• 6 7 11 (\ 17 2.43 Fertilizer mi,ture, 5O-percent mineral and 5O-percent organic ammoniates, with slud~e superphosphate ' .. 16 25 8 51 59 2.36 Onion, sliced hulb ...... __..._..______28 52 23 76 99 1.90 Castor·bean meal'______._.. 15 27 1 H ·15 1 1.67 Fertilizer mixtures, commerciaL _____ ...______• 25 289 134 404 1.40 Superphosphat~, common , ______•___ __ 15 27 o 34 34 1.26 lI-lolasses, water, and yeast____ ..._____..______..__ _ 17 37 16 29 45 1.22 Muriate 01 potash , ______...... ______.. 5 5 o 6 6 1.20 No bait.___ . ____ •._••____ • __ .,,_•••______. 59 123 25 85 110 .89 I!oney, water, and yeast...______2 4 1 1 2 .50 Lemon, sliced .._...... ____...______..__ __ a 9 2 .22 Superphosphate, sludge , _____ .....__ ..._...______._ 11 24 5 .21 Apple, sliced .....__ .....__ •___ ....._..__ •___ ...... __ 2 10 2 .20 Boney, watcr. and isopropyl alcohol , ______.. 4 7 -"'-'il ...... i- 1 .14 Potuto seed piece~, freshly cut._____ •___ •• ______•.__ •. 2 6 o 0 o .00 TotaL..__ • __ ....______.._. ______--n75 'l.ii«\"'l,525 7,167 ~--- I Different times th!1t 1 or more traps were set for approxImately 24 hours . • Thb column also inclUdes those adults taken whose sex was not determlnoo. 'A specially prepared mixture contaIning fish meal, cottonsl'Cd meal, and animal tankage, and containing 7 percent 01 phosphori~ scid, 5 to 6 01 ammonia, and 5 01 potash. • A constituent of plant fertilizer mixtures. , Containing 7 pl'rccnt 01 phosphoric acid, 5 to 6 01 ammonia, and 501 potash. , 5 re., 5 ce., nne! I to 2 drops. respectively. During the investigations several of the substances known to be attractive to the flies, and 11 number of other materials, were used as baits in the field traps previously described. The various baits were tested under as comparable conditions as were obtainable. All the materials were tried under similar conditions at the outset, and those that proved most effective and were readily available were used in the later trapping studies, hence the difference in the number of trap set tings. The relative effectiveness of the various substances as baits is shown in table 13. It is evident from these data that the greatest 26 TECHNICAL BULLETIN 723, U. S. DEPT. Ol!' AGRICULTURE number of flies were taken in those traps baited with fish meal, animal tankage, dried blood, and cottonseed meal, or in those baited with fertilizer mixtures containing these materials. These O1'ganic constit uents of fertilizers were attractive to the flies when in the fertilizer mix tures and when used alone. Perhaps these materials proved most effective as baits because of their greater stability and not because they were more attractive than some of the other substances. Even though no specimens were taken in the traps baited with potato seed pieces, adults were observed on several occasions on freshly cut seed potatoes being planted in the field. The flies were apparently attracted to the juices of the tubers, as they were not observed on uncut or healed seed. LOCATIONS FREQUENTED BY ADULTS The location of adults at various times of the year, as indicated by the relative numbers taken in traps set in different situations, is indi cated by the data of table 14. These records were obtained from a total of 1,798 individual.trap settings made 011 130 different days. The small commercial traps proved satisfactory except that they could not be obtained with small enough meshes in the screen to retuin the lmdersized adults. A more satisfactory screen with 16 meshes per linear inch was used on the larger traps. The traps were set in the uncultivated areas late in the spring and in the summer months in an effort to determine the habitats of adults during these seasons. During th.~ year as a whole, it would appear that the adults were most abundant in freshly cultivated areas having no vegetation and were next abundant in freshly cultivated ureas with vegetation. TABLE l4.-Habitat of aduUs of the seed-corn maggot, as indicated by numbers taken in traps set ,in various locations at Chadbourn, N. C., and Charles/on, S. C., 19£7-31 Culth'ntcd areas Uncultivated areas With vegetation Without vCgetntlon ---....- ----1-----,----1 l~fg~~~h l'ntl~r In ditches I trees Freshly Crusted Freshly Crusted and weeds Month plowed soil plowed soil 8. ~ §. 8. /a ~ 8. .~ .~ .~ .~ .~ .~ -~ rn _c= tn .... ::= til -= UI ..wE til ..w= v:. ....:.C:: til ~d e :§= e :§~ e :g~ E :g- e i:g b IE :g!; f :g~ :- ..: :- -< :-. -< :- ..; :- I..: :-..: ::--< -----I-l'·-ro-. No. No. No. No. ~Vo. No. No. No. I~~ iVO. Ivo.llVO. iV•. January. •.•• 16 2.9 35 7.4 31 6.1 7 10.3 _••••..••••••••••• _...._,_ ...... Februarr.••.• _..... _..... 22 2.7 47 6.4 19 9.3 ._••••1. •..••••_...... _..._..... Mareh_...... 29 30.9 3-1 21.3 36 25.1 --...... - •••••---.1 """ .... __ ...... _,,_...... ApriL...... 28 2.5.2 36 11.1 13 58.6 12 4.2 12 1.7 .• _...... _ May...... 166 4.9 67 1.7 15 4.1 8-1 1. 3 00 .4 18 . 1 I 6 .2 June...... _ 83 1.0 80 1.9 !lO 4.7 30 .2 30!1 .1 17 .1 • ..._ ~~~ilSt=:==:=: ~? IJ I£':~ [~ 1:& ill 1:~ ... :~J~.. ~. 11 ~.O! ~ ¥:~ September.___ 19 8.4 28! .8/11 ,4/ 26 1.0 ...... :...... / .....1 .""_",, October...... 51 2.6 391 2.3 39 3.6 ...... _...... L ...... jl _...... T November ... 56 6.7 52 1 5.6 1 54.0 ...." ...... 1...... \...... -...._- ...... December.... 36 2.2 391 2.8 I 10 6.0 10 2.8 ...... :...... 1...... Total I .•••• 5151'---" 4521'=1396(==:(""""2271= J.I2',=r-M"t=::-::j'12-:-= A;e~l:a~~••_.... 6.5 •__ ... <\.9 )'''___ 7.~ )___ ...1 2.2 ....-. .51 ..... 1 .2 I ..... 1.·1 1 Total number 01 times that 1 or more traps were set for approximately 24 hours: 130. 'l'otal !lumber of individual trap settings: 1,798. BIOLOGY OF SEED-CORN :wrAGGOT IN SGUTH ATLANTIC STATES 27 Freshly cultivated areas apparently were preferred to those with crusted soils. During the summer the adults apparently sought pro tection from the heat by frequenting uncultivated vegetated areas or shaded locations as well as being present, during at least part of the (lay, in cultivated areas both with and without vegetation. During February 1927) at Chadbourn, adults of Hylemya cilicr'Ura were found on both sides of a screen 7 feet high coated with a sticky material and located along the edge of a wooded area. It was evident that the flies were going back and forth from the woods to the culti vated field. The weather was mjld at the time, and there were flow ering plants in the wooded area. Two adults were found on Septem ber 2, 1931, at Charleston, 8 and 9 feet above the ground on the field side of a similar screen. PERIOD OF ADULT ACTIVITY The data presented in table 15 indicate t.hat the adults are most active during midday in the ,vinter and early spring months, most active late in the Itfternoon and early in the morning in the hotter part of the year, and about equally active during these parts of the day in March, April, and October. Su~h reactions are to be expected as a result of temperature conditions. In general the relative activity of each of the two sexes at various times during the day was the same as that of the combined population. No males were captured during the day in the field in August and September. Throughout the year as a whole, males and females were taken in the field traps in the pro portion of 1 to 3.9, respectively. This difference in the ratio of sexes was probably due largely to the shorter lives of the males and to greater attractiveness of the baits to the females. TA~L"E 15.-Nltmber ~nd sexes of adults of the sced-corn maggot trapped at different t~mes of the day durmg the vanous months of the year at Charleston, S. C., 1927-31 I Adults takl'n per trap per day during- Total adults taken per trap per day I,ate nrt~rnoon and :Mean Month early morning Midday period temper, ature j -----I---~----·~---- ______I._~_ra_Je_s r!~~s ITotal ;~ m~~~s Total ~'r!~~s 'l'oto.l ___ 1\'umber NumberCv.umberCivumber Number Number NI,mbtflNU7nber Numbtr 0 F. January...... 0.37 1.251 1.62 1.26 4.32 ij.58 1.6.1 5.57 7.2Q 52.1 Fehruar,...... ,. 1.08 3.13 4.21 1.71 Ii. 54 8.25 2.79 9.67 12.46 53.0 March...... 2. 12 12.62 14. 7~ 1. 98 1·1.16 16. 14 4.10 26.78 30.88 57.8 April ...... 2.98 8.4-1 11.42 4.67 10.81 15.48 7.6,'; 19.2.'; 26.90 6,';.9 May...... 2041 2.76 5.17 .38 .71 1.09 2.79' 3.47 6.26 72.7 June...... __ .21 Ai .68 0 .10 .10 .21 ,57 .is I n.7 July...... 42 .64 1. 00 .3 .42 .72 .72 1.00 1. i8! 8.1.4 AUgllSL...... 02 .61 ,63 0 .0.1 .03 .02 .&1 .66 SO. 5 September...... 04 I.Ti 1.31 0 .55 .55 .04 1.82 I.S'l 7i.i October...... 13 2.28 2.41 .09 2.05 2.14 .~'2 4.3.1 4.5.; 68.4 November...... ZI 3.88 4.11 .16 2.80 2.96 .39 \ n.m! i,07, 58.8 December...... 07 1.3.; I 1.42 .13 I. 77 I. 90 .2Q; 3.12 3.32! 50.3 Average...... --:Mr3.22I--:ui6I--:8913.li91~l.73;""6.!il8.&l~-iiii:5 1 Ba.,ed on records of a total of 1,58-1 males and 6,993 females taken during 40 months. , In months in which trapping was actively conducl.('d. 28 TECHNICAL BULLETIN 723, U. S. DEPT. OF AGRICULTURE DEGREE OF ACTIVITY Activity of the flies was noted to be afi'.9ctecl by light, wind; rain, and t£'mperature. Adults were never noted to be active during the night, although caged specimens were frequently watched, and tmp lights were set on severnl occasions. Caged adults were observed to be inactive at sunrise (5:45 a. m.), July 29,1931, but quite active at 8 a. m. that same day. Strong wind and ruin were observed to reduce adult activity to n, great extent. Temperature has a marked effect on the activity of the flies, as shown in table 16. It would seem that the adult is active to some extent at temperatures as low' as 320 F. However, their movements 0 0 0 are restricted at temperatures below 50 and above 80 , and above 90 very little movement was observed unless the flies were caged or dis turbed. During the summer months adult activity is apparently limited, the flies evidently remaining in shaded, cool places such as ditches anel vegetated areas. They are acti.ve during warm periods throughout the ,,,"inter and are most active in the spring and fall months. During the prevalence of temperatures considerably below freezing the. flies were observed to be apparently dead, lying on the suil on their backs. They remained in this condition for several days, but many of them resumed activity when the temperatme rose to 50 0 or above. From 7 to 85 percent of the adults of various ages caged in the insectary died during a cold snap in December 1925, when a minimum of po was reached. Mortality was highest among the older groups of fiIes. TABLE 16.-Effect of temperature upon activity of adults of the seed-corn maggot, Chadbourn, N. C., and Charleston, S. C., 1926-31 ~ Tern· Date and time of observation I Location pera· Adult actlvity and weather ture OF. JlIll. 14, 1927, ahout 1 p.m...... Insectary....__ ..... 57 FaIrly active and feeding. Jan. 15, 1927. 12 noon ...... do..__....__..... 35 None; clustered in part of cage nearest to sun, or in protected pIBC('S in soil. Jan. 16, 1027{' a. mo...... do....__ ...__ .... II All lying on bottom of cage, seemingly dead. 4 p. ID ...... __ ...... do__ ...... 37 Do. Jan. 17, 1027{9 a. m ...... do____ ...__ ...... 35 Do. 4 p. m ..__ ... __ ....._...do__• __ • ____...__ 60 11 01 the 18 flies regained activity, otber 7 apparently dead. Jan. 18,1927,4 p. m __ ...... __ .do....____. ____ . 65 Only 2 of the above mentioned 18 flies, actually died, others active. 0 n, m ...... do...... 24 None. Jan.27,1927 10-11 a. nl...... ___ •.do..__ ...... 28-20 Slight; 2 trying to get wBt~r from frozen sponge. 1-2 P. m ...... __...do...... 34-35 Slight. 1 36-34 None noted 30 NOllO. r:.10 a.~~======moo ...... ====:~g:=::::::=:::::do...... 34 Slight. 12 noon...... do.._...... 45 Sllght to moderate. Jan. 28, 1927 1-2 p. m ...... do...... __ ..__ 5.1-55 Moderate; making short flights, very nctive wh~n disturiXld. j 2-4 p. m ...... ,...__ do..__ ...... __ .. 55-56 Moderate. 5-5:30 p. m ....__ .. 'l ...--do...... --... 55-53 Slight. Feb. 16-17, 1927, 2p.m.-l0 B.m", Field...... ! 55-76 Active; fed on flowers and Qviposlted In field. 8:30a.m._.--..... Outdoor cage ..__ ..__ ! 41 Very slight. 10 B. m __ ...__ .....1,.....do.....___ ...... l 47 M odcrBte. Feb. 21, 1927 10:30 a. m ...__ ••_.: __ ...do...... , 43 Slight. { 11 a. m.-3 p. m ....1.....do...... 1 50-56 Moderate; short J1ights, (e.d freely. 6 p. m ...... __ ..1...__ do.._...__ . __ ..., 49 . Slight. BIOLOGY OF SEED-CORN MAGGOT IN SOUTH ATLANTIC STATES 29 TABLE 16.-Effed of temperature 1tpOn activity of adults of the seed-corn maggot Chadbourn, N. C., and Charleston, S. C., 1925-31-Contillued Datc and time cfobservation Location ~;~: Adult activity and weather turc I DRI------S:3O B. m...... • Outdoor...... 42 Slight. 10 a.m..••••.•..••....•do...... 51 l\Iodprate; making short flights. Feb '2 1927 11 a. m .• clear•...... •.do •.•....••..••.I( 59 Acth·c . • -, I 12 noon, hazy....•...•• do... .•.••.•..•. 59 Less acti\"e. 2 p.m., clear.•....•.•••do...... 67 Acti\"e. 5:30 p. m•....•.••...... do...... 59 Slight. IS a. m .•• ·...•.••. Field .••. .•••.•....•. 45 None. 9 a. m ...... do...... •..••.. 54 Slight; only few seen. ICI-ll a. m ..•.••..•.•••.do...... 62-70 Acth'e and abundant on flowers, none seen in air. 12 noon-l p. m ••••..•••.do..•••..•..•.•. i2-i3 Very aeth'c, hovering in air abo\'e \"egeta· tion. and acti\"e in freshly plowed field being planted to potatoes. Feb. 25, 1927 2 p. In•...~...•....I..... dO...... 74 Slightly less active. 4 p. m., ram...••....•..do..•••..•...••. 56 Nonc. 5 p. m., partly .••..do..•••.••.•.••. 56 Do. cloudy. Feb. 26, 1927{B:30 B. m ...... I do...... 38 None. I p. m .•••••••••••••••••do..••••.•.••••• 52 , Slight. Apr. 30, 1925,l! a. m ••...••••...... do ...... 72\ Slight. (Wind approximately 25 miles per hour.) May I, 1925, 5 p. m ..•••.••••••.L.... do..•••..•.••.•• 75 Very active. (Only slight wind.) May 15, 1930,2 p. m •.•.•.•••...1 •....do...... 86 Moderate in protected places; flying only when disturbed. May 20, 1930, 2 p. m ...... l.....do ..•.•..••••••. 9211 female seen 4 feet below normal ground 1e\'el ill ditch, none in fields. July 20,1931,2 p. m ••••••.•••..! Edge of woods...._. 91 I female on ground under tree .. July 22, 1930, 12 noon •••...••••.!.•••.do ...... l 92 l' None in fields; a liberated adult flew to shaded place in vegetation. and remain· ed there until it became e.tposcd to sun, when itmoved to another shaded place. July 29,1931, 6-S a. m ...... Field and insectary ..1 t SO None in field, very acti\"e in cages in insectar)·. July 30, 1930, 12 noon...... Field...... : 94 None in field. 5 adults were lightly dusted with lime and liberated in the field; all sought shelter in the shade or I I flew away at once. Oct. la, 1925, 9 n. m...... --•.1Insectary.....•••...i 55 Slight. Dec. 20, 1929, 12 noon....____ ...! Field...... ] 35 Principally inactive; found in cracks in soil. L Approximate. SEASONAL ABUNDANCE OF ADULTS Based on relative numbers of specimens taken per trap per day during the various months of the year, as shown in table 17, adults of Hylemya, cilicrura were most abundant in fie1ds in the eastern parts of North Carolina and South Carolina in March and were least abundant in August. It was evident that there were peaks of adult population during the spring and during the faU months. TABLE 17.-Seasonal abundance 1 of adults of the seecl·corn maggot as indicated by trapping experiments at Charleston, S. C., and Chadbourn, N. C., 1927-31 A ver(lge adults tllkNl per trap per day - !___ 1WeIghted . • Clfonth i 1927 1 I9!lS 1 IO!!!) I 19:JO ! 1931 menn' }-·a-e'b-~-~r-ir-·i-.~-~·-.:-:-::-:-::-:-::-:-:-::-:-::-:-::-:-:-::-:--: s~~~~:: \Xl.'m~~: II' XU1n ISU~~;f :::~~~:~ I sum:f~ March...... ( .... f 00.2 ·10.6 16.0... . • 3!J.6 ApriL...... 5.81 46.7 \ 57.9 16.3 23.5 ~f!l}·...... ' 1.7 19.9: :I.i I 3.3 4.2 June...... ' 4.2 1.5 \ 1.3 f'S 3.0 July...... 3.3 "...... 1.9 I.;' Allg11SL ___ .. ___ 4. ___ ..... ____ .. ~_"_~ _____ .. M: ,,~r .. 6 t .-_~_.: .. 5 .. 6 b~~b~r~~r:::::::::::::~~~:==~::~:=:::::: : ~:~ '1' 1: ~ j ~:~ I I~:~ i.~ Xo\'cmhcr...... · 12.5 9.1: 2.5.31 23.6 13.fI Decemher...... ' 12.5 3.6 . S.2 i 2.0 t...... 5. S t Based on 6.533 adults taken in 825 lndh·idual trap settings of I day eaeh on liS different days. Thus there were an avcragc of 2.6 days per month during the 45 months co,'crcd whcn 1 or more traps were set. I Weighted according to number o( traps ;;ct. 30 TECHXICAL BULLETIN 723, U. S. DEPT. OF AGRICULTURE lUTING :Mating was observed in only three instances during the studies 1 reported upon in this bulletin. In one of these the adults emerged on J ~larch 20, 1926, and mated on April 6, 17 days after emergence. Another pair emerged on June 11 and mated 5 days later. The age of the third pair at time of mating was not !mown. PREOVIPOSITION PERIOD The preoviposition period in the case of 4 mated females ranged from 5 days in June to 18 days in :March and April, with an average of 12.5 days (table 18); and in the case of 19 unmated females the period ranged from 7 days in July to 55 days in October, November, and December, with an average of 25.58 days (table 19). OVIPOSITION The eggs are laid singly, or in groups, near or on sources of larval food in the soil. As many as 10 eggs have been found in one cluster. As a rule the eggs are deposited just beneath the surface of the soil, in cracks in the soil, or in crevices between the soil and the intended food. Occasionally they have been found directly on the food and IlOt in contact with the soil, but in every such instance the food was in con contact with soil. Favorite places for oviposition are near or OIl sprouting or partly decaying beaIls, peas, or similar huge seeds; near or on decaying remains of such crops as cabbage; and near or on such organic fertilizer materials as fish meal and cottonseed meal. They have bcen found beside tender, healthy seedlings of such crops as spinach or cabbage and occasionally nenr or on partly decayed and ( e:.\.-posed potato tubers. The eggs have not been observed on or near sound potato seed pieces in the field. Oviposition usually follows se\Teral attempts of the female to find a suitable spot in the soil or around the intended larval food. The ovi positor is pushed into the soil for a moment, during which the egg or eggs are laid, and is then quickly moved to !l. new position. A female was found to deposit as many as 49 eggs in a single da:r. Odpositiun was apparently most prevalent at temperatures of fro III ':)00. to 80° F.; in other words, when the adults were most active. A mOIst, freshly cultivated soil is apparently preferred, as eggs were seldom found in very wet or dry areas. .. Oviposition of Reared Adults Since the mating of adults in confinement was somewhat of a rarity, complete oviposition records of fertile females were limited to four speci mens, the data concerning which are given in table 18. These adults deposited from 46 to150 eggs each, during periods ranging from 5 to 26 days after emergence. The average number of eggs laid per female was 97.25, with no eggs in the bodies of any of the females at death. r~ ~ 'F .,. -:-...:;7 ,. -- ~ r TABLE 18.-0t'ipllsition records of 7/lllted females of the sccd-corn 1/Iaggol, Chadbourn, N. C., 1920-27 Eggs doposlted on tho (ollowlng fhlY~lifter emergence I'l'otsl Preo"l· Mesn DOtll Dllto FomulnNo. d~~~~.fl~~'~~~~: cmerJ:,:cd 1111110(1 --,----, .~-,-, . , , , I ,- I I IS 10 20 5 10 12 15 III 17 _~..-=-_~-=:.._::.. ~ ~ period ~~ ------.---I------I--~ ...I--.....·I--I-._-I----I--...- !~ oJ'. No. N o. No. No. No. No. No. No. Nil. No. No. No. No. No. No. No. DaU6 40 Ii lOa 18 511.6 1 (511) :Mllr.2(1, 19211 Allr. f! 411 ~ ...... H 110 12 71. 7 2 (1011)...... ,. •••• MillY J2. 1927 ('l :i9 HI 21 · .. ·3 . ...~.- 46 15 71.2 21 , ..~ ~ ~ 20 2 gJ 3 (1111)...... ••••• (0 •.•. 1') 150 75.2 M'" ~ ~ ~ 12 :12 Ii 10 45 .. ~ dO'" .... af> 5 4 {14n). __...... JtUlU 21,1927 ') 10 _.-~ -- ------W ~ --~ 12.50 ••••••• _ -- ,. --~ ~ .. .. Oi.25 --- -- .. -- -- ...... - -- --...... - -... - . ~ --~ - .. -- A\'erllge...... -...... ". - .~-'---:--.-- .-.~.--.....:--:- ~ I No eggs. woro prescnt In hadles oCIIDY oCtllIl SllOc1nwlIsut time 01 ("lIlth. , .'or 2·hour periods IrolU eU\~rgunl'eto nllulll\, I'0slllun. z sUnknowlI. t;.I .... g:.. S .... Z l/l S j::q ~ ~ ~ ~ t.j~ l/l ~ 32 TECHNICAL BULLETIN 723, U. S. DEPT. OF AGRICULTURE Records of oviposition by 19 apparently unmated females are shown in table 19. These flies deposited from 1 to 209 infertile eggs each, t during periods of from 7 to 68 days after th1eir emergence. The av )~ erage oviposition was 37.79 eggs pel' fly, wit 1 an average of 5.89 eggs in their bodies at death. TABLE 19.-0viposition records of apparently 1ttullaied females of the seed-corn mag got, Charleston, S. C., and Chadbourn, N. C., 1926-80 Fe- I Preovi- 0\'1- Total I Eggs in Mean m31e Date emerged I position position eg::s' de-, bodyat temper- No. I 1 period period posited death ature ! ---I1.------Feb. 15.1926..______•. ______. ____ .,I~~ 11 23 Numbtrl~----;;-P:14 0 4S.14- 2. ______Apr. 16.1926______1 33/ 14 68 0 66.68 3.. _____ 1' ____ do______• ______._.______, 12 22 12 0 65.47 ~ ______Apr. 19,1926______, 29 22 7, 5 67.77 5 ______1 ._do______.._____ ..______: 31, 1 4 17 65_67 . L:=:::!s______Il\fay ~f:n: 13.1927 1::::::::::::::::::::::::::::::::::1_____ . __ .. _____ ••• ______J 1f)'11 13~ 282~ 0~ i ~U~73.53 9. __ •___ •.May2O.1926·______....______• __ 1 12 29 127 ~ I 73.~ JO ....._, __ •__ dO ______•______'.. 13! 3 21 13 71.15 11. _____ ) l\fay 24. 1926______: 47 I 23 0 76.43 12._____ 1July H. 1927. ______•• _____ •• ______, 7 i 30 19 7S.23 13. _____ ' July IS. 1927____ ...... ______•• ____ , 20 , 44 2 SO. 76 14 ______1July 21. 1927______: 15 2 11 0 SO. 09 15 _____ July 23. 192i _____ ._ ------1 14 15 209 0 1 76.06 16______Aug. 6, 1927______23 I 2 0 SO. 49 I 17..____ Sept. 24. 1930____ .. _____ .______53 9 S 0 I 60.53 IS ..____ I Sept. 28.1930____ ..______' 42 28 12 0 59.05 19------r Oct. 10. 1925______. ______• 1~ ___1____3_ 43,~ A'·emge______, 25.58 10.681 37. 79 ~l------ 1 All infertile. I From emergence to end of oviposition period. Table 20 gives data relative to groups of reared adults that were confined in various types of cages in efforts to induce mating. The ( T~BLE 20.-Records of adults of the seed-corn maggot confined after emergence in various types of cages to induce mating, Chadbourn, N. C., 1926-27 i Prcodposition, I Eggs deposited ,; . period f i ______a*~~pI e~~~~d ;I··~~ijs:.,. Size of cage 1M t , 1 pair observed matin!! On .-\.pr.6. , I pair observed mating On l\[n,' 18. I The parasite Aphaereta mu~cae .-\shm. was ~enred from these c~ges. I BIOLOGYO:t' SEED-CORN ~rAGGOT IN SOUTH ATLANTIC STATES 33 flies in the larger cages were kept there ouly from 2 weeks to 1 month after emergence, 01' until mating WfiS observed, and were then isolnted in the low, cylindrical cnges, men suring npproxiumtely 2 by S inches. It will be noted that the grenter number of fertile eggs were obtnined from those ndults kept in the larger, outdoor cages for n period nfter emergence. Oviposition by Field-Trapped Adllits A summnry of the oviposition records of ndults trl1pped in the field n t vnrious places nnd n t difl'el'en t times is shown in tnble 21. It Cfin be seen th:1t ndults were taken in the trl1ps in ench month nnd thnt eggs were lnid by these ndults in ench month. Eggs were deposited by at lenst some femnles {,f most of the groups tnken, Il1nl in most cnses they were Init1 sholtly nIter the flies were trnpped. This would indi cnte thnt ndults nre present tll1el rendy to o,-iposit under fn,'ol'llble con ditions during the grenter pnrt of the yenr. The gren.test n ,-emge lllUll bel' of eggs pel' field-trnpped femnle were laid in. August itnd Sep tember bY' ndults tmpped iu August, nnd th(' next gl'entest number in Jnnunry and Febmary by ndults tmpped in Jnnm1r}'. The indicH tions were thnt vel'y little, if nIlY, oviposition OCCIU'S in the field during the summer nnd thnt the ndults become gl'itdd while nwaiting more favorable soil ann food conditions, thereby nccounting for the lnrge number of eggs laid by the August-tl'llpped flies. The lowest nxerilge number of eggs pel' femnl~· were deposited dming April nne! ~ft1y by ndults trapped in April. This rnny be nccounted for by se\" ernl fnctors, among which may hitvc been thnt a huge percentage of the ndults tmpped in April had not muted; or thnt the ndults present in the fields in April, wbich consist hugely of newly emerged specimen:,; of the lnrge spring brood, do not oviposit extellsiyely until el1riy in the fall. The iLwrnge number of eggs pel' female deposited by 1,874 fe mules trnpped in the fields throughout the entire period of the studies was 3.87. TABLE 2J.-S/lm1l!ory of oviposition records oj adulls of the .•ced-corn moggot trapped in fields, Sortlt Carolina and SOllth Carolina, 1925-31 Adult females trapped Eggs depOSited ~lelln 'fotal 'fotnl mnge of ovillnsition !,eriells AVeril1!'e temperq· I.ure" t Dates of trappin;: 'number 'fot~1 per : tnken > . felllnl~ ------,----,------_. Sumb., SlImber OF. Jan. fr'2i_ ,0 Jan. "-Feb. 0 _ 657 9.:19 '18.5 Feb. 10-2; 15G Feh. I~-Apr. 26 ,39 ~, ,~ ,jl~ 4-52. i "Iar. 1-2\) 315 Mar. 3-:'C.y III 91.i . 30, ~9 S-62.2 Apr.2-28 • ::'11 Mlr. 5-~rny 1.1 :11:1 ' 136 5:'UHl7.~ May 3-30 223 : ),!rlyI-July 15 791 3.;';; fill. S-'!l. '! June 2-30 2fh) ; june 5-Aug. Ii 820 3.09 7~.1l-7U. 0 July 3-2:1 _, liS July IJ-SO[lt. ~ 272 4. on 81.11-8:1. 0 Aug. )5-26 SG . -', UJ!. 16--Bcpi. 7 711 13.2'J 71.1-78.1] Bcpt. S-23, , 97 :'ept. ;;"Dec. )3 ;72 j. tHl 5S. 4-7-1, 7 Oct. 1-31 20(1 O~t. 2-;:'<0\'. 19 67!l 3.39 6'2.3-<3,4 Xo,', I~-IP rh~ 'XO\~. 15-Jan. 2.'\ 177 2. 72 H. f>-5:'I.' Dec. 5-)4 )25 Dec. II-Jan. ~I 31U 2.,19 ~:1.14!.1 ------.,~.-"------~ -.,----~ 'fotnl or a'·er.ge, "" 1.874 ,,219 3.87 I Hunge of melln temperature oC period it·,\·ul,·c'] oC e,eh ye'lr. 34 TECHNICAL BULLETIX 7:!3, r. S. DEPT. OF AGRICULTURE LONGEVITY OF ADULTS 1I. ...LoDdgevitly dli~tadoff the four pairsdthat m.ahted are given ill table 22. )~ .l.Vl.ate rna es ve rom 24 to 35 ays, Wlt an average 0 f 29 days; and mated females lived from 31 to 40 days, with an average of 34.25 days. In general, males that. emerged in November lived longest and those that emerged in August lived for the shortest period; females that emerged in September lived longest, and those emerging in June had the shortest life. TABLE 22.-LoT/ueltity of mated pairs of adults of the seed-corn maggot, Chadbourn, Y. C., and Charleston, S., C., 1926-27 l\[ean tempera Emergence to death Len~th of life - ture I Pair No. --.------~--~----- I I Male Female l\fale Female ______!I _____:,Ol_a_le___.l_____F_e_m_u__le______t Dav! DaVB o j"'. • F. L______),[nr. 20 to Apr. 20, :'oIar. 20 to Apr. 20, 31 31 56.6 56.6 1926. 1926. 2.______•______, :'olay 12 to June 5, 1927. ),[ay 12 to June 12, 24 31 70.9 iI.7 1927. 3.______. ______l\[ny 12 to June 7, 1927_ :'oray 12 to June 21, 26 40 I 70.9 71.3 I 1927. 4______1June 21 to July 26, 1927_ June 21 toJuly26, 1927. __35_1___35_ 75.2 ~ A,erage•• ______29.0 34.251•••-.---1------ I For each liCe period. In table 23 are presented data concerning the length of life in con finement of males and females of renred groups of adults. These spe~ imens probably neyer mated, as it was necessary to keep them in the ( smaller types of cages in order to get definite longevity records. The average life of 338 males emerging during 11 months of 1927 was 29.2 days, with a range of 3 to 100 days; the avel'llge life of 386 fe males was 38.7 days, with a range of 3 to 104 days. TABLE 23.-Summary by months of the longeltity of reared groups of adults of the seed-corn maggot in confinement, Chadbourn, N. C., 1925-27 i ! I l\[ales Females i :1------1-----:------Range of mean Emergence period 1Num-; I-ength of lire Num- 11-_L_en_g.,..th_o_f_lI_fe_l temperature I , ber i , Weighted j ber Weighted I , ______~,___ Range I mean I Range mean i :'o[ales J Females ... , ------1---1--- I j Dav. Dav· Dau~ D~U' I • F. i • F. 13 -1-10 21.3 12 12-50 26.214I.1f 41.7 8 37-16 4l.4 7 3-1-75 58. 3: 49. I : 51.5 45 7-W 15.6 42 7-33 J5.7: ~2 5 0 425 Apr.~T!>/~~~~:::::::::::::::::i 1-30______: ! 92 3-19 : 16.2 ! 111 8-58 22. 7 I 57-M II 57-67 38; 5-37 I 12. 2 f 40 8-50 22. I _ 67-M f o:Hl7 ~~~ ::~t======::===:==! 32 14.2 ! 70 3-18 15.7 c 74-77, i4-7i 7i , t:~ 1 14.6 75 I 3-18 18. 2 75-i8; 7S-78 4 n-7 6.5 2 7-28 17.5 80.9 I SJ.2 ~-\u~r t~·.:===:=::==::=::==:=r l 31-103 A:I.O 59.7 Sept. 22-28--.------.1 2 I 18-88 , 53.0 5 ! 61.5 Oct.](}--16______•______16 3;-74 ( 59.5 9 3 74. I : .,1-1)5 - 48-1)5 No\-. 8 ___ .. ______; 1 9-104 1____It ,'_____ 27-100 !i 66.8 13 , 27-10.1 72.5: 45.7i~ 3S.7 : _____ •___..____ • __ Summary______...__ : 3.18 3-100 ! 29.2 386 ! 3-104 , i I i I From first emergence to end of weighted mean period. BIOLOGY OF SEED-CORN MAGGOT IN SOUTH ATLANTIC STATES 35 ENTIRE LIFE CYCLE Records of rearings of groups of specinlens during various times of the year under approximately normal field conditions are given in table 24. These inunature stages of the insect were caged in earthen pots sunk to the level of the soil in open fields. The period from hatching of the egg to adult emergence ranged from 14 to 88 days, with weighted means of from 15.3 to 77.1 days, at mean soil temperatures of from 45.3° to 81.4° F. Mortality was least during the early part of spring and greatest during midsummer. TABLE 24.-Duration of periods from hatching, to the emergence of the aduU of the seed-corn m Eggs hatching Adult emergence Duration of period i I :'>[enn ~~ Date Num· Date Per· Range Weighted ature J I her rent I menn J Jan, H. 1030. ______--I , 100 :'>far.I6-31-______26.0 Dau'l~a:-l--:;-61-76 &1.3, 51.27 Feb. 26,1935______; 150 l\lnr. 25-Apr. 2. ___ •••______93.3 27-35 27.9; 62.1 Apr.~, 103.1______46 I Apr. 2i-l\Iny 2•. ______6i.0 2t-29 25.9 , 67.7 Apr. H. 1930••______1 50 May 2-IL ______,,2. 0 18-22 20.0 i 67.6 Apr. 23'1929------'1 75 1:llay 1&-17_ .. ______12.0, 23-21 1 23.1 " 71.9 Apr. 29, 1930•. ------25 ,------le·.Oo 'I' --.-IS-:2--I-I------lii.--7- Mny I. 1930 ..______25.i l\-Iay IG--Z2______.. _ ,-----=/.-O-·~ May 19. 1930.______25 I June 8-13. , .•______16.0 20-25 IS. 7 " 76.8 ~~~. ¥,:, 11~~-:======:=1 ~.I-S(.-Pt.-i2-=i4=~==:======:=== 116:. go !--iG-6--ilS--s ------llt/~. 0o--,! ----·sao-.' 9- l Aug. 28, 1930..___ • ______.. ~ 25 Sept. 1:1-15 .. ______1 6 l l 3 ======:======: ! i lU .1 Sept.l~~::: 211, 19~1930..______... __ .___ i 50~ : ~~f,t:Oct. 20-25,______l~l~::======: 62.0I~:g 21-26}tl~ 24.1 1 65.6~U Oct.. 5,1930.. ______.__: 50 I Oct. 2S-Nov. 13 __ .______. 70.0 I 23-39 27.91 61.0 No\,. 11, 1930 •••••______.! 50 ! Jun. 12·Feb.1.....___..___ 50.0, 62·82 69.0 47.0 Ko\". 29.1930 .....______•••, 50 Feb. 8-25.. __• ____ ...... __ 34.0: 7l-8S, 77. I ~5.3 I Total or range.. __ ._••: S-I6 i-..-..-··-·-..------..------·--·----. -(-).0-3-.3i 1-1-88 j 15.3-77.11 4•,.3-51.4 J 01 the various specimens in\"ol\·ed. J For 2·hour periods at a depth of 3 inches in the soil. The period from egg deposition to adult emergence us indicated by rearings of 181 udult.s from two lots of eggs deposited on February 25 and 26,1935, ranged from 23 to 37 days, with weighted means of 30.2 and 33.0 days, at mean soil temperatures of 62.2° and 62.3° F. These specimens were caged under the approximately normal field conditions described in the preceding paragraph and developed during the period that potato seed pieces are damaged by the insect in the Carolinas. In table 25 are grouped data concerning the average length of tinle spent at different times of the year hy the seed-corn maggot in its var ious stages of development. The lack of more records of the duration of the preoviposition period, resulting from the failure of the adult to mate in captivity in most cases, limits the total life-cycle data to the cases of a very- few individuals. JUdging from the results of this com pilation, it lll1ght be regarded that the period from oviposition to ovi position might cover from 18 to 233 days, with weighted mean periods of 20.4 to 176.1 days, at mean temperatures of 75.2°-100° F., and 40° 56.6°, respectively. The total length of life from egg deposition to death of the adult might range from 39 to 250 days with means of 39.4 to 193.1 days at temperatures of 100° to 40° in the case of males, and 36 TECHNICAL BULLETIN 723, U. S. DEPT. OF AGRICULTURE from 44 to 255 days with means of 46.4-198.1 days at that same tem perature range, in the case of females. It should be noted that these figures represent the adding of the various developmental periods of different groups of specimens rather than of one group through all the periods or stages. TABLE 25.-Summary of duration of various stages 1'n the life history of the seed-corn maggot, North Carolina and S01lth Carolina, 1925-8/; Duration of period lUean Stage or period temperature W oighted range Range tnean Davs Davs OF. Egg...___ •••_...... 1-11 1-8.5 83. i-12.5 Lan·a...... 5-i8 6.5-60.9 100. (HO. 0 Pupa ,...... __ ...... i-l26 i.9-88. i 100. (HO. 0 Adult (mated) preo,iposition ...... 5-18 5.6-18.0 i5.2-56.6 75.2-100 Egg to egg ...... _...... IB-233 2O.·l-1i6.1 and { 40-56.6 Adult (4 m!l~ed): O\'lposltlon ...... _...... 8-21 B-21 i5.~-56.6 Entire adult life: :Males...... _...... _...... __ . 26-35 21-35 i5. 2-56. 6 Fem3les....__ ...... _...... _.•..••__ ... 31-10 31-10 75.2-56.6 Entire lire (egg deposition to adult death): 39-250 39.4-193.1 100.0-10.0 ~~~';;1~s': ~ ~ ~::::::: :::::::::::::::::::::::::::::::::::: ::::: ::::: ~I 44-25.1 46.4-198.1 100.0·10.0 1 Includes prepupal period, a part of the larval period that is spent within the puparium. NmlBER OF GENERATIONS It was not possible to make continuous Tearings uf the seed-corn maggot in captivity owing to the few cases in which the insects mated under the conditions imposed. No definite data were therefore ob tained concerning the number of generations a year possible. Nu merous records were made, however, of the development throughout the various stages, und these would indicate that, in the Coastal Plain of the Carolinas, there might be as many as three generations during the active breeding season from late in September through April. SEASONAL OCCURRENCE Weather conditions are important factors in the development, activ ity, and abundance of the seed-corn maggot. The species evidently thrives best during periods when the mean tempera tures range between 55° and 65° F. and in the presence of abundant moisture. Develop ment is retarded greatly at mean temperatures below 45° or there about, and is apparently greatly restricted at mean temperatures above 75°. All stages of the insect will develop at constant. temperatures as low as 40° and as high as 95°, and a limited number of larvae and pupae survived continued e),,-posure to a temperature of 95° to 100°. Eggs, newly hatched larvae, and newly formed pupae were found to be par ticularly susceptible to high temperatures.. As the species seems to prefer freshly cultivated areas with little or no vegetation for its breed ing place, it is readily understood whv the mortality is so high during the hotter part of the vear in the coastal area of the South Atlantic States, where soil temperatures at and near the surface often exceed 100° at this time. BIOLOGY OF SEED-CORN :\IAGGOT IN SOUTH ATLA...~TIC STATES 3i :More or less extensive breeding wus found to occur under field con ditions in the coastal areas from late in September through April, and there were indications that limited breeding takes place at other times in those areus. There were no apparent demarcations of broods, all stages being present during the greater part of the active breeding season. There were two distinct periods of greatest abundance, how eyer, these being late in the fall and early in the winter, und late in the winter and early in the spring. Eggs of the most abundunt brood, or broods, of the insect are depos ited late in December, in January, and in February. It is the larvue from these eggs thllt injure potato !:ieed pieces. The early potato crop is plunted in the Carolinus in the latter part of ,Jnnuary, in Fehrunry, and early in ~rarch, find the muggots were found feeding on seed pieces throughout February and :March and into April, the heaviest infesta tion being noted enrly in Murch. The latest in the spring that eggs WNe observed in the field wus April 18. These eggs were found in the soil near a partly buried spinach leuf. For several years large numbers of larvae taken from potato seed pieces in February, yInrch, !lnd April, were caged in earthen pots sunk in the open. field. Adults emerged in these cages from March 22 until :May 6, the peak of the emergence being from ~rarch 25 to April 20. Puparia were found in the field throughout the winter und spring months. but were most numerous late in ~rarch and caI"ly in April. Adults were most abunclunt in the field in ~rarch and April. Judg t ing from rearing records, adults might be expected to develop about the middlp of ~[ay from egg's deposited in the middle of April. Although repeuted eft'orts were mude to locate immature stages of the seed-com mag.~ot, in the field, during the period extending from ),[ay until late in September, none was found. There flre se\-eml rec ords of adult emergence, howeyeJ', which indicate that there was proh ably some breeding during the summer. On .Tuly 30, 1926, an adult emerged from soil taken from a field on July 15; and on September 15, 1931, two adults, a male and a female, issued from soil taken on Sep tember 2 from beneath a large tree in a cultin-tted field. Fish l11('al had been mixed into the soil under the tree on August 2(j. Only a limited numhrr of adults were seen or captured during the summer months. It is thought that Hle species pnsses througll the tmfn.yorable summel' period largely us adults of the late sf'ring' brood. Females were ob sen-eel at ya.rious times during that period' in cool. moist locutions such ns the bottom of ditches UJl() under trees and other yegetation. Xo e\-idences were noted of fi. diapause of the pupal stnge clUJ'ing the sum mer as reported hy Rekatch (2£, p. 269) in 1931 to han:- occurred in Tranf.caucasia. Itis entirely possible, however, that such a condition does exist in this country but was not ohserved dlll'ing the course of the studies reported herein. \\1H~n adults were tn.ken in traps from ~ray through Octob('l', they usually laid lnl"!:!:e numhers of eggs nJmost lmmediately nfter heiJlg caged. E,-idently they hlld not' found field conditions 'very suitnhl(' for oviposition during that period, but th('y did d('posit ('~!!S fre('ly w~en cugeel in a relativ('ly cool location nnd oHr moist soil contuinin~ sUltahle lU.l'val food. The earliest that eggs w('re found in the fall wns S('ptembr.r 27, when two females w('re seen to deposit seven eg!!s in n low, moist plflce l1eur some organic fertilizer in It freshly plo,~ed field. Thre(' of the eggs 38 TECHNICAL BULLETIN 723, U. S. DEPT. OF AGRICUL'.rURE hatched on September 28 and two on the 29th. Eggs were laid in the field in increasing numbers in October and early ip. November. The larvae of this brood often cause severe injury to spinach, cabbage, and other seedlings. Pupation of these larvae was observed to occur dur ing the period extending from late in October through November and into December. Adults of the fall brood, or broods, began emerging early in November and continued to issue throughout January, the peak of emergence occurring during November and the early part of December. All stages of the species were found in the field throughout the winter in eastern North Carolina and South Carolina, but less abtmdantly than in the fall and in the spring. NATURAL ENEMIES Possibly because of the fact that much of its life cycle is passed protected underground, the seed-corn maggot does not appear to have a great number of natural enemies. Chittenden 9 observed in the District of Columbia on June 17, 1905, that, "the wasp Xylocrabro stirpicola Pack. employs the fly among others \"ith which to store its nest." He also (3) reports that adults are affected in Alabama by the fungus Empusa americana. Swenk (29) states that the adults are frequently severely attacked by fungous diseases (Empu,sa). During the spring of 1925 in Pamlico County, N. C., the author obseryed seyero,} species of spiders that had adults of Hylemya cilicru1"(L as their prey. These were identified by C. R. Shoemaker 10 as Lycosa arida Walckenaer, Trochosacineren F. (?), Pardosn sp., Olubiona obesa Hentz, and Phidippus auda:c. Hentz. It is not known how important these spiders are in the biology of the seed-corn maggot, but since the adults of Hylemya cilicl'ura are alert and active, probably not a great number are killed by predators. :\Iany odults were killed in field cages and traps by ants during warnl seasons. It is possible that ants are able to capture the flies in nature. The author had occasion to observe many caged adults that were killed by fungous diseases during warm, moist weather, but he did not note anv occurrence of the disease under field conditions in the Caro linas. Perhaps the cool weather preyalent during the period of greatest activity of the insect served to keep the fungus in check. On February 4, 1926, an adult of Scatophaga jurcatn Say was ob served carrying a living adult of Hylemya cilicru1"(L 11 oyer vegetation in the laboratory yard at Chadbourn, N. C. According to Dr. Aldrich this species had not been reported before as attackin!! H. ciiicrura, but was known to be predacious upon the common housefly C\lusca dome8 tica L.). Scatophaga jurcata is rather abundant in the Carolinas during the period of activity of the seed-corn maggot. It was fre quently taken in traps set in the fields for H. ('ilicrura, and usually killed seyeral of the latter species in the traps before they could be examined. On many occasions this predacious fly was seen on the outside of outdoor cages containing adults of the seed-corn maggot. Durin!! the period April 22 to 28, 1927, adults of what afpeared to be a species of parasitic Hymen...optera emerged from t~le soi in a large outdoor cage at Chadbourn, N. C. The cage contaIned laryae and • l~npuhll.hcd notes. "I.otter from J. E. Oraf to author. 11 Doth id~ntified by J. l\L Aldrich. DIOLOGY OF SEED-CORN :i\IAGGOT IN SOUTH ATLANTIC STATES 39 puparia of Hylemya cilicrlll'a. Lnrnle of H. cilicrul'a were exposed in glass vials to these pamsites at various times from April 22 to JuneIO. The pal'llsites were obselTed to sting and evidently oviposit in the bodies of the maggots nlmost immediately in n great majority of the cases. Adults of Aphael'eta m1l8cae Ashm. 12 emerged from the puparia of larvne of H. cilicruJ'a thnt hnd been caged with the pamsites. As many as 15 of this hymenopteron were known to ha\'e issued from 1 host puparium, the host case being left empty. The parasite has not been observed to attack H. cilicrura under field conditions, but it seems possible and probable that it does do so, since at the time of hatching the larvae are near the soil surface. In JitllUnry 1926 it female adult of Hylemya. cilicrul'a that had died in a cage itt what was considered u. premature date Wl1S found to con titill apparently several thousand nematodes in the thick, semitrans pitl'ent fluid in its abdomen. No other case of nematodes attltcking the seed-COIll maggot was observed dUl'ing the course of the studies. On :\{arch 26, 1930, a larvn. of the seed-com maggot, approximately three-fourths grown, was observed feeding ill a cage on the body of a hnlf-gruwn larva of its own species. The indications were that the prey was not dend when attncked. The cage contained soil in which was mi'md an ample supply of food consisting of cottonseed meal and fish menl. No other case of apparent cannibalism by the seed-corn maggot was observed during the illvestiga.tion. Although no record or observation of such feeding has come to the writer's attention, several kinds of birds have been seen frequenting fields in which the flies were abundant, and they probably feed to some extent on the adult of the seed-corn mnggot. The Bureau of Biological Survey has records of the following birds feeding on the adults of the seed-corn maggot: Old-squnw [duck] (Clangula hyemalis) , black swift (l.Yephoecfies niger), crested mynah (Aethiospar crista tel lus), palm warbler (Dendroica palm arum), and English sparrow (Passer domesticus). Of these the black swift and the crested mynnh are not found in the eastern part of the United States. SUN[~[ARY The seed-corn maggot (Hylemya cilicrura (Rond.)) occurs through out the arable portions of the -enited States, ns well as in many other compnrable parts of the world. In its wide range of food plan t.s nre several important vegetable crops, including beans, cabbage, potatoes, and spinach. Studies of the biology of the insect ill the eastern p0rtions of North Carolina and South Cnrolina were conducted from 1925 through 1935 in connection with attempts to ded.sa n means of pre\'enting damage to potato seed pieces and to spinnch seedlings by the insect. The results of the control phase of the irwestigations have been published separately. Eggs nre deposited in the soil, on or near a source of larval food. The length of the incubation period ranges from means of 1 to 8.5 dnys, at mean temperature? ranging from 83.7° to 42.5° F., respec tively. Eggs hatch at mean temperatures as low as 40° to 45°, and as high as 95°. None hatched at a mean temperature of 100°. n Determined by A. B. Gahan, ~hittenden Xo. 10i05 40 TECHNICAL BULLETIN 723, U. S. DEPT. OF AGRICULTURE The larvae were found to feed in the soil upon a variety of both living and dead plant and animal matter. Partly decayed vegeta tion and the sprouting seed and seedlings of such crops as beans, peas, and spinach are favorite foods. Organic fertilizer materials also were fotmd to serve as larval food. Potat.o seed pieces were fed upon only when poorly healed, or when decaying. Potato sets with well heaJed cut surflLces were not attacked by the insect. The duration of the larval stage ranges from 5 to 78 days at mean temperatures of from 100° to 40°-45°F., with a range of from 7 to 26 days during the period that seed potatoes are attacked in the coastal areas of the South Atlantic States. Larval development is greatly retarded at temperatures below 50°. Comparatively few larvae survived when caged in the open field from May to October, I or at constant temperatures of 95° or above. The larvae appear to have three instal' periods, judging from the structure of the pharyngeal apparatus. The prepupal period lasts about 2 days during the spring months. Pupation was found to take place ill the soil, usually near the place of larval feeding, and at an average depth of 2X inches in fl, moist sandy loam soil. The pupiLl stage lasts from 7 to 26 days at mean soil temperatures of 83.7° to 54.1 ° F., from 7 to 18 days during the , spring months, and as long HS 126 days at a temperature of 40°-45°. Relatively few pupae surviverl constant temperatures above 90°. A.dults emerge from the soil only during the night or very early in the moming, and are able to reach the surface from depths as great as 7 inches in a sandy loam soil. The flies were observed to feed upon the flowers of a number of cultivated and wild plants. The organic fertilizer mltterials, fish meal, cottonseed meal, animal tltllkage, and dried blood proved most effective a::: baits in trapping ( the adults. It was indicated from bait-trap recorJs that the adults are most abundant, during the year as a whole, in freshly cultivated nonvegetated areas alld that they sought protection in cultivated and tmcuIt.ivated [J,reas with vegetlttion during the summer months. Adults are most active during midday in winter and the early spring months, and during the late aftemoon and early moming Itt ot,her timeR of the yenr. Adult Itctivity is restricted Itt temperatures below 50° F. and Itbove 90°. Some Itcth"ity WitS noted at temperu.tures as low as 32°. 'Wind anel rain greatly decrease adult activity. Adults are most abundant during the spring and late in the fall, and leust abundant in midsummer. ylo,ting of caged adults was rare. The averu.ge preoyiposition period of mated females wus 1~.5 days, and the avemge number of Pggs laid by mated females wus 97.25. These were laid during periods ranging from 5 to 26 days after emer gence. Eggs were deposited in the insectary dllring all months of the year by acllllts caught in trapR. The greatest number per field trapped femil.le were lnid in August onel September und the next greatest number in January and the early part of February. Appar ently fleW conditions had not been entirely favomble for o,"iposltion, and the recently trapped, gravid females deposited eggs freely as soon as caged in tho more favomhle environment. The avemge life of mated females in confinement wus 34.25 days, and that of mated males was 29.0 days. As the adults rarely mated in confinement, records concerning the entire life cycle and the number of generations are limited. Howover, BIOLOGY OF SEED-CORN MAGGOT IN SOUTE ATLANTIC STATES 41 the indications were that the period from oviposition to oviposition might range from means of 20.4 to 176.1 days, at ranges of mean temperatures fmm 75.2°-100° to 40°-56.6° F., respectively. The total length of life from egg deposition to death of males might range from 39 to 250 days, and from 44 to 255 days in the case of females, bot.h at mean temperat.ure ranges of 100°-40°, respectively. Results of rearings, under ttpproximately normal conditions, of groups of speci mens at various seasons of the year showed a range of 14 to 88 days, at mean soil t.emperatures of from 81.4° to 45.3°, respectively, for the period from hatching to adult emergence. The time from egg deposi tion to adult emergence during the period that potato seed pieces are attacked was found to range from 23 to 37 days, at mean soil temperatures of 62.3° F. There were indications of three possible generations during the active breedmg season. The seed-com maggot wftS found most abundant during the cooler parts of the year. The imma.tnre stages were seen in the field from late in Sept,ember through April in eastern North Carolina and South Carolina. Peaks of population occurred dm-ing October and Novem ber, and from the latter part of Februa.ry through March and April. Only adults, chiefly females, were found during the summer months. However, there were evidences of restricted breeding ill cool, moist locations dm-ing that period. No pupal diapause was noted, although it is possible that some specimens live through the summer in such a state in this country . .Although the seed-com maggot was found to Imve several para sitic and predatory natural enemies it did not appear that thesE' play a very important role in reducing the abuudance of the species. LITERATURE CITED (1) A~[ERICAN ASSOCIA'rfON OF ECONomc ENTO~!oLOGISTS, COlllITTTEE ON X O~IENCLATURE. 1931. COM~!oN NAMES OF INSECTS APPROVED FOR GENERAL CSE BY THE AMERlCAX ASSOCIATION OF ECONOMIC ENTOMOLOGISTS. .Tour. Eeon. Ent. 24: 1273-13]0. (2) BISROPP, F. C. 1925. FLY TRAPS AN'D THEIR OPEnATION. U. S. Dept. Agr. Farmers' Bull. 734, 14 pp., illus. (Revised.) (3) CHl'rTENDEx, F. H. .. 1902. so~rE INSECTS INJURIOUS TO VEGETABLE CROPS. • •• U. S. Dept. Agr. Diy. Ent. Bull. 33 (u. s.), 117 pp., illus. (4) 1916. ON THE DISTRIBUTION OF THE IMPORTED CABBAGE AND ONION ~rAGGOTS. (Sci. Note) Jour. Econ. Ent. 9: 57!. (5) FITCH, As.'.. 1856. FIRST AND SECOND REPORT ON THE NOXIOUS, BENEFICIAL, AND OTHER INSECTS OF THE STATE OF NEW YORK. 336 pp., illus. Albany, N. Y. (6) HARUKAWA, CHUKICHI, and J(UlIASHlRO, SABUR(}. 1930. STUDIES ON THE SEED-CORN ~lAGGOT, UYLE~IYIA CILICRURARON DANr, IN J.-I.PAN. I. ON THE SEASOJ:iAL LIFE-CYCLE AND ;HABITS OF THE SEED-CORN MAGGOT. Ber. Ohara Inst. Land\\'. Forsch. 4: [371]-382, illus. (7) --- TAKATO, RY(}ITr, and J(U~!ASHIRO, BARUR(}. _ 1932. STUDIES ON THE SEED-CORN MAGGOT. II. Ber. Ohara lust. Land\\'. Forseh. 5: [457]-478, illus. 42 TECHNICAL BULLETIN 723, U. S. DEPT. OF AGRIOULTURE (8) --- TAKATO, Ry6ITI, s.Ld KUMASHIRO, SABUR/). 1933. STUDIES ON THE SEED-CORN MAGGOT. III. ON THE METHOD OF CONTROL OF THE SEED-CORN MAGGOT. (I). Ber. Ohara Inst. Landw. Forsch. 6: [83]-111. (9) --- TAK}.TO, RY/)ITI, and KUIIIASHIRO, SABUR/). _ 1934. STUDIES ON THE SEED-CORN MAGGOT. IV. Ber. Ohara Inst. Landw. Forscb. 6: [219}-253, illus. (10) HAWLEY,1. :[\1. . 1922. INSECTS AND OTHER ANIMAL PESTS INJURIOUS TO FIELD BEANS IN NEW YORK. N. Y. (Cornell) Agr. Expt. Sta. Mem. 55, pp. 949- 1037, illus. (11) HAWTHORN, LESLIE R. 1932. SPINACH UNDER IRRIGATION IN TEXAS. Tex. Agr. Expt. Ste.. Cir. 66, 11 pp.' illus. (12) HOWARD, L. O. 1900. A CONTRIBUTION TO THE STUDY OF INSECT FAUNA OF HUMAN EXCRE MENT. [WITH ESPECIAL REFERENCE TO THE SPREAD OF TYPHOID FEVER BY FLIES.] Wash. Acad. Sci. Proc. 2: 541-604, illus. (13) HUCKETT, H. C. 1924. A SYSTEMATIC STUDY OF THE ANTHOMYIINAE OF NEW YORK, WITH ESPECIAL REFERENCE TO THE IIIALE AND FEliALE GENITALIA. N. Y. (Cornell) Agr. Expt. Sta. Mem. 77, 91 pp., illus. (14) HUFF, CLAY G. J 1928. NUTRITIONAL STUDIES ON THE SEED-CORN MAGGOT, HYLEMYIA CILICRUR.-I. RONDANI. Jour. Agri. Research 36:625-630, ilIus. (15) LEACH, J. G. 1926. THE RELATION OF THE SEED-CORN MAGGOT (PHORBIA FUSCICEPS ZETT.) TO THE SPREAD AND DEVELOPIIIENT OF PDTATO BLACKLEG IN MINNESOTA. Phytopathology 16: [149}-176, illus. (16) LINTNER, J. A. 1882. FIRST ANNUAL REPORT ON THE INJURIOUS AND OTHER INSECTS OF THE STATE OF NEW YORK.. 381 pp., illus. (17) LUGGER, OTTO. 1896. INSECTS INJURIOUS IN 1895. Minn. Ent. Ann. Rept., 155 pp., ilIus. (18) MALLOCH, JOHN R. 1920. DESCRIPTIONS OF DIPTERA OF THE FAMILIES ANTHOMYIDAE AND SCATOPHAGIDAE. Ohio Jour. Sci. 20: 267-287, illus. (19) PETERSON, ALVAH. 1924. SOlliE CHEIIIICALS ATTRACTIVE TO ADULTS OF THE ONION IIIAGGOT, (HYJ,EIIIYIA ANTIQUA MEIG.) AND THE SEED CORN MAGGOT (HYLE MYIA CILICRURA ROND.). Jour. Econ. Ent. 17: 87-94. (20) REID, W. J., JR. 1936. RELA?'!?N OF FERTILIZERS TO SEED-CORN MAGGOT INJURY TO SPINACH SE";DLINGS. Jour. Econ. Ent. 29: 973-980, illus. (21) ---, WRIGHT, R. C., AND PEACOCK, W. M. 1940. PREVENTION OF DAlfAGE .~y THE SEED CORN MAGGOT TO POTATO SEED PIECES. U. S. Dept. Ag. .£fech. Bull. 719, 38 pp., illus. (22) REKATCH, V. N. 1931. STUDIES ON THE BIOLOGY AND CONTROL OF THE SEED-CORN MAGGOT (CHORTOPHILA CILICRURA ROND.). Trudy Prikl. Bot., Gcnetik i Selek. (Bull. Appl. Bot. Genet. and Plant Breeding) 26: 267 285, illus. [In Russian. wit.h English summary.] (23) RILEY, C. V. 1869-77. . .. ANNUAL REI'ORT[S] ON THE NOXIOUS, BENEFICIAL AND OTHER INSECTS OF THE STATE OF 1I11SS0UltI Mo. State Ent. Rpts. 1 and 9. (24) RINGDAHL, O. . 1933. OVERSIKT AV I SVERIGE FUNNA HYLEMYlA-ARTER. Ent. Tidskr. 54: 1-35, ilIus. (25) ROBINEAU-DESVOIDY, J. B. J 1830. ESSAI SUR LES IIIYODAIRES. Mem. Acad. Roy. Sci. Inst. France, v.2. Paris. (26) RONDANI, CAlIIII,LO. 1865. ANTHOIllYIN..E ITAI,IC..E COLLECT..E DISTIN0T..E ET IN ORDINEM DIS POSIT..E In his Species Italicro Ordinis Dipterorum, Dip terologiro Italicro Prodromi, v. 6, Pars Quinta, Anthomyinro. BIOLOGY OF SEED-CORN MAGGOT IN SOUTH ATLANTIC STATES 43 (27) SCHOENE, W. J. 1916. THE ECONOMIC STATUS OF THE SEED-CORN MAGGOT (PEGOMYA FUS CICEPS ZETT.). Jour. Econ. Ent. 9: 131-133. [Discussion of T: H. PalKs, p. 133.] (28) STEIN, P. 1916. DIE ANTHOMYIDEN EUROPAS. TABEr,LEN ZUR BESTIMMUNG DER GATTUNGEN UND ALLER MIR BEKANNTEN ARTEN, NEBST lIIEHR ODER WENIGER AUSFUHRLICHEN BESCHREIBUNGEN. 224 pp. Berlin. (Arcll. Naturgesch. Jahrg. 81 Aht. A, Heft 10. 1915). (29) SWENK, MYRON H. 1909. SOlliE INSECTS WHICH ATTACK THE PLANTED SEED OF CEREALS. Nebr. State Bd. Agr. Rept. 1909: 235-246. (30) WALSH, B. D. 1870. LARV..E IN THE HUlIlAN BOWELS. Amer. Ent. 2: 137-141, illus (31) WASHBURN, F. L. 1905. THE DIPTERA OF MINNESOTA Minn. State Ent. Ann. Rpt. 10: [19}-168, illus. (32) ZETTERSTEDT, J. W. 1845. DIPTERA SCANDINAVI..E v. 4. Lundre. 1 ORGANIZATION OF THE UNITED STATES DEPARTMENT OF AGRICULTURE WHEN THIS PUBtiCATION WAS LAST PRINTED Secretary of Agriculture____ : ______HENRY A. WALLACE. Undcr Secretary ___ ------CLAUDE R. WICKARD. Assistant Secretary ______------GUOVER B. HILL. Director of Information______M. S. EISENHOWER. Director of Extension lVork ______M. L. WILSON. Director of Finance ______W. A. JUMP. Director of PersonneL ------ ROY F. HENDRICKSON. Director of Research_ ------JAMES T. JARDINE. Director of Marketing______MILO R. PERKINS. Solicitor ______------~ ------MASTIN G. WHITE. Land Use Coordinator ______M. S. EISENHOWER. Office of Plant and Operations ______ARTHUR B. THATCHER, Chief. Office of C. C. C. Activitie8. ______FUED W. MORUELL, Chief. Office of Experiment Stations ______JAMES T. JARDINE, Chiej. Office of Foreign Agricultural Relations __ - -- LESLIE A. 'VHEELEU, Director. Agricultural Adjustment Administration __ - - R. M. EVANS, Administrator. Bureau of Agricultural Chemistry and HENRY G.KNIGHT, Chief. Engineering. Bureal' of AgriCllliural Economic8. ______H. R. TOLLEY, Chief. Agricultural illarketing Service __------C. W. KITCHEN, Chief· Bureau of Animal Industry ______JOHN R. MOHLER, Chief· COlllmodity Credit Corporation_ ------CARL B. ROBBINS, President. Commodity Exchange Administratto1t ____ -- -- J. 'V. T. DUYEL, Chief. Bureau of Dairy Industry ______O. E. REED, Chief· Bureau of Entomology and Plant Quarantine_ LEE A. STRONG, Chief. Farm Credit Administrat,ion ______A. G. BLACK, Governor. Farm Security Administration_ ------ W. ,Yo AI,EXANDER, Administrator. Federal Crop 11tsurance Corporation_ ------LERoy K. SMITH, llfanager. Federal Surplus Commodities Corporation ___ _ MILO R. PERKINS, President. Food and Drug Administration ______WALTER G. C.UIPBELL, Chief· Forest Service ______------.. _. - --- EARLE H. CI,APP, Acting Chief. Bureau of flome Economics _____ - - . ------LOUISE STANLEY, Chief· Library ______CLARIBEL R. BARNETT, Librarian. Division of J[arketing a,td llJarketing AgreeMILO R. PERK.INS, In Charge. menis. Bureau of Plant Industry ______E. C. AUCHTER, Chief. Rural Electrification Admini.~tration _____ • _ _ tI.~ ItRY SLATTEUY, Administrator. Soil Conservation Service ____ • __ • __ . ______• H. H. BENNETT, Chief· Ureather Bureau. ______• ______. ______FRANCIS ,Yo REICHELDERFER, Chief· This bulletin is a contribution from Bureau of Entomology and Plant Qllarantine~ I-,EE A. STRONG, Chief. Division of Truck Crop and Garden Insect W. H. WHITE, Principal Ento Investigations. molagist, in charge. 44 U. s. GOVERNMENT pRINTING OFfiCE: 1"0 For sale hy the Superintendent oC Documents, Washington. D. C. • - - - Price 10 C('nts .' 0. r .' .__ .... -.__ .n 1 • t ! i j .' ., OJ "of .. 'J , . -:1 .I ;~ . ~.' .;; L :J ! ~ ~ l_..r.-..l ____