Attractants for Synanthropic Flies. 2. Response Patterns of House Flies'to Attractive Baits on Poultry Ranches~

H. R. WILLSON" AND M. S. MULLADepartment of Entomology, University of California, Riverside 92502

ABSTRACT

A proteinaceous attractant, prepared by freeze-drying fermented whole egg solids,was found to attract Musca domestica L. and other synanthropic Diptera. In fieldexperiments, a mixture of 2 g of the attractant and 2 g of dichlorvos sugar-bait in-creased fly collection two-fold on manure substrate in trays set on the ground andthree-fold in suspended bait units over the sugar-toxicant bait alone. This increasewas due primarily to the increased response of nulliparous and parous females in whichvitellogenesis was about to occur. Attractancy of the bait declined sharply after 48hours of field exposure.

The location of bait stations significantly affected the number, sex ratio, and femaleage structure of the flies collected. Stations collecting the greatest number of flies weregenerally situated at the ends of the cage rows in sunlight-shade border areas. Fly col-lections from areas of greatest fly activity were characterized by a high proportion ofhoth nulliparous and parous protein-searching females, and the sex ratio in these high-activity zones approached 1. East-west and north-south preferences of certain femaleage groups were manifested in the collections.

Studies on lise of poison haits for fly control werereported as early as 1914 hy Morrill, and use ofsuch haits was recommended by Howard and Hutch-inson (1917). The early poison baits included suchfood attractants as beer, fish, and bananas. Theefficacy of dry baits was reported by Gahan et al.( 1954) and Mayeux (1954), and commercial em-phasis centered on dry sugar-toxicant formulationswhich lack volatilc attractants.

Weismann (1960) studied the sensory functions ofhouse liy antennae. He concluded that their sense ofsmell is not highly developed, and questioned thepotcntial of odoriferous haits for fly control. Mourier( 19(4) found that the searching behavior of a flyleads it to non attractive sugar-baits and that the "herdinstinct" of flies will cause more to follow. Thus,factors other than volatile attractiveness influence flyresponse to baits.

Attractants for house flies were studied by Brownet al. 1961), Beroza and Green (1963), and Frish-man and Matthysse ( 1966). These attractants gener-ally fell within the categories of putrefaction prod-ucts, fermentation products, and simple carbohy-drates. Since the house fly requires both carbohy-drates and protein at various stages of its adultlifespan (Derheneva-Ukhov<l 1935, Goodman et al.196X), <l bait should include an admixture of sub-stances which will be attractive both to adult fliesin search of sugar and to those searching for pro-tein.

A volatile attractant, prepared by freeze-dryingfermented whole egg solids, has been developed for

1 Dirtera: Muscidae."This investigation was surrorted (io rar\) by NIH Training

Grant no. ESOOO84 from the National Institute of EnvironmentalHealth Sciences and (in rarll hy the Coachella Valley MosquitoAbatement District. Manuscrirt from a thesis submilled by the1st author in rartial fulfillment for the Ph.D. degree. Universityof California. Received for publication Ocl. 12. 1972.

"Present address: Department of Entomology, New YorkState Al'ricultural Exreriment Station. Geneva 14456.

the control of Hippelates eye gnats' at the Universityof California, Riverside (Mulla et al. 1973) and itis attractive to most synanthropic Diptera. This at-tractant is now known as LursecC·"". The attractantis easily mixed with commercial poison sugar-baits toprovide an attractive bait mixture consisting of pro-teinaceous attractant, sugar arrestant, and a knock-down toxicant (dichlorvos) . Such an admixturefacilitates application of measurable quantities into"bait units" (Mason et al. ]971), which can beplaced at selected "bait stations" (Keller et a!. 1956).In addition, sueh a bait mixture ean he placed instrategic situations on the ground in fly-infested areas.

The importance of integrating bait location withfly behavior has been emphasized by Davison (1962)and Keiding (1965). Observations on the ethologyof various Diptera on poultry ranches by Andersonand Poorbaugh (1964) demonstrated aggregation offly populations that varied from species to species.Presumably this dispersion of fly populations wouldinfluence effectiveness of poison-bait stations usinglow-order attractants.

This study was initiated to determine the efficacyof an attractant used with a poison sugar-bait againsthouse flies in various locations on poultry ranches.In addition, the effect of the location of bait stationswas studied in regard to the number, sex ratio, andage structure of flies collected.

Materials and MethodsThis study was conducted on 2 caged layer poultry-

houses in southern California. One ranch was nearthe community of Perris and henceforth is referredto as Ranch PA. This ranch housed approximately30,000 layers in 12 houses interconnected by

• Diptera: Chloropidae.• Registered trade name aprlied for by McGlaul'hlin, Gormley,

King Co., Minnearolis, Minn.

815

816 ENVIRONMENTAL ENTOMOLOGY Vol. 2, no. 5

screened ceilings and enclosed aisles which ran per-pendicular to the cage rows. Poultry droppings wereremoved semimonthly, and naled fly spray was ap-plied when considered necessary. The other ranchwas in the town of Mentone and henceforth is re-ferred to as Ranch MA. This ranch housed 15,000layers in 4 separate buildings. Poultry droppings wereallowed to cone and were partially removed semi-annually. This practice of manure management waspart of a biological control program in which para-sites were released semimonthly, and use of fly sprayswas avoided.

Four experiments were conducted: 2 to determineefficacy of the attractant, and 2 to study the effectof bait placement on fly collection.Experiment I: Sugar-Toxicant Bait With and WithoutAttractant.

In the 1st experiment, dischlorvos sugar-bait withattractant was compared to dichlorvos sugar-baitalone. For the 1st tests, the baits were placed on apoultry-manure substrate in bake pans (10)<10X2in.). Pairs of these bait units, one with attractantand one without, were placed under the cage rows ofRanch PA. After 24 h, the bait units were collectedand the flies were removed, identified, sexed, andcounted. Table 1 shows bait dosages and number ofreplications.

In 5 tests, dichlorvos sugar-bait with and withoutattractant was compared in matched pairs of baitunits suspended from the ends of the cage rows(Fig. 1). The bait unit was a small 276-ml cup.For 24-h tests were run on Ranch PA, and one 24-htest was run at Ranch MA. In addition to recordingspecies, sex, and numbers collected, physiological ageof female house flies was determined by examinationof a representative sample of adults drawn from thecollection of each bait station. To determine physio-

FIG. 1.-A pair of suspended cup units used for eval-uating attractiveness of baits.

logical age, the females were dissected in saline solu-tion in spot plates, ovaries were removed and trans-ferred to a glass slide, and the stage of cogenesis wasnoted according to the criteria of Adams and Mulla(1967) developed for eye gnats. Parity was deter-mined by presence or absence of fat bodies, conditionof ovariole pedicels and tracheoles, and bunchedcondition of ovarioles (Anderson 1964).Experiment II: Longevity of the Attractant 011 Ex-posure.

The 2nd experiment on attractant efficacy meas-ured effectiveness of the attractant over time. Ex-posure periods of 24, 48, and 72 h were compared inan experiment using 18 bait units, one unit repre-senting each of the 3 time periods at 6 selected locion Ranch MA. The bait unit used was the larger1.5-liter can unit (Willson and Mulla I973a). Eachreplicated set of 3 units was suspended from the endsof 3 adjoining cage rows. To compensate for apossible spatial effect on a particular unit within aset of 3 units, 3 baitings were run in which the posi-tion of each time-designated unit was rotated. Ineach baiting all 18 bait units were started simultane-ously, and thereafter the units designated for specificexposure periods were capped 24, 48, and 72 h afterinitial placement.

Experiment Ill: Effect of Directional Exposure 011

Fly Collection.The 3rd experiment was designed to measure the

effect of directional exposure on the numbers, sex,and age of Hies collected. The larger 1.5-liter baitunits, baited with 4 g of attractant and sugar-toxicantbait mixture (50:50 by wt), were suspended from theends of the cage rows nearest the 4 corners of RanchPA. This experiment included 3 24-h collections.

Experiment IV: Effect of Bait Placement Along theCage Rows.

The 4th experiment was designed to determine theeffect of bait station loci on numbers, sex, and agestructure of flies collected. At Ranch PA, 5 baitstations were established along the central cage rowsin the E half of the ranch and 5 in the W half,and each station consisted of 2 bait-pan units havingmanure substrates. Three collections, 24 h in dura-tion, were obtained 2 weeks apart during the monthsof April and May. Age-structure analysis was limitedto Hies collected in the stations at the E half of theranch. At Ranch MA, two 24-h collections weremade to determine fly activity along the cage rowsfrom the E to the Wends. As stated earlier, poultrydroppings at Ranch MA were dry and coned in con-trast to biweekly removal of droppings on Ranch PA;thus, a moist substrate had to be provided for theattractant sugar-bait mix. A bait unit was designedthat consisted of a 500-011 plastic cup containing amoist vermiculite bait substrate and a hood to shieldthe bait from fresh droppings. Five stations weredesignated along a cage row from E to W. Eachstation consisted of 3 bait units situated along 3parallel cage rows.

October 1973 WILLSON AND MULLA: HOUSE FLY RESPONSE TO ATTRACTIVE BAITS 817

Statistical TreatmentsStatistical separation of means resulting from

matched fair trials was made with Student's t-test forpaired variates. Data from the exposure-period ex-periment was analyzed by a random plot analysis ofvariance. The chi-square test for independence wasused to detect significant variation among the num-bers, sex, and age-group proportions in collectionsobtained from various bait stations.

Results

J::xperiment J. Sugar-Toxicant Bait With andWithout Attractant

The number of flies collected by dichlorvos sugar-hait with the attractant was significantly greater thanthat collected by sugar bait alone in every comparisontest conducted. When the baits were placed in panunits having manure substrate, addition of the at-tractant increased fly collection 2-fold. In suspendedbait units, however. the mean ratio of the number offlies collected by sugar-toxicant-attractant mixture tosugar-toxicant bait alone was 3: 1, and the presenceof attractant increased the percentage of females inthe catch by about 10%. As a result, the ratio offemales collected in suspended units with attractantto those without WitS approximately 4: 1 (Table 1).

In the physiological age analysis of females col-lected in units with and without attractant, theaverage number of females collected by each baitwas multiplied by the corresponding age-group pro-portions to obtain the age structure characterizingthe sample collected. Fig. 2 illustrates the results.Nulliparous age groups 1+2 and 7+8 and parousage groups 7 +H did not appear to be affected by thepresence of the attractant. Nulliparous (N) andparous (P) groups 3+4, 5+6 and 9+10 showedincreased response to the attractant. The peak re-sponse of nulliparous females was confined to stages3+4 in contrast to the parous peak in stages 3through 6.

Experiment I/. Longevity of theAttractant on Exposure

The number of flies collected for the 24- 48- andn-h exposure periods per site in the 3 bai~ings 'wereaveraged to give a mean count per period per site(Table 2). Of the total n-h collection, approxi-mately 75% was obtained in 24 hand 93% in 48 h,respectively. The proportion of females in the countsdeclined with increased baiting period.

Experiment II/. Effect of Direction Exposure onFly Collection

Fig. 3 shows the age structure of female houseflies collected from the 4 corners of Ranch PA.Most of the flies were collected at the SE corner andwere characterized by an average sex ratio of 48.5%Q; the fewest were collected at the opposing NWcorner and were characterized by a sex ratio of41.5 % Q. A chi-square test for independence be-tween proportion of age groups per station did notdemonstrate significant difference between the agestructure of flies collected per station. The relativeproportion of nulliparous females in age group N3+4 appears to correlate with the sample size. Asa result, the stations collecting the most flies arccharacterized by a high proportion of both nullipa-rous and parous protein-searching females. This re-lationship is similar to that found for the sex ratiowhich approaches one in high activity zones. Theproportion of nulliparous females in the Scornerunits was higher than that of the N units. In iso-latel incidences, the age group, P 5+6, would occurin relatively high proportions in one SW corner.

Similar results, concerning the effect of directionalexposure on fly collection, were extracted from thesuspended-bait comparison tests of Experiment ].In the age analysis of females baited by the attractant-sugar-bait mixture at the E and Wends of RanchPA, a low but significant «0. J 0) level of directional

Tllble 1. - Numbers and sex ratios of house flies collected by units baited with dichlorvos sugar-bait alone andsuj:tar-bait plus attractants.

Mean no. house flies/unit % females

CollectionperiOd

No.replicates

Sugar-bait+ attractant

Sugar-bait

Sugar-bait+ attractant

Sugar-bait

Oct. 6, 7Oct. 12, 13Oct. 27. 28

June 30. JulyJuly 8. 9July 15. 16July 28. 29Sept. 28, 29

Pall ullits with mallure substrate alOlIR caRe rowsBuit-dosURe/l/llit = 2.5 R sl/Rar-bait alld 5.0 R mixture (50:50 by wI.)9 16.9 2.4*" 75.09 23.9 12.0 71.69 92.3 49.8*** 73.0

Cup units suspended at end of caRe rowsBlIit-dosllRl' = 2.0 g sugar-hait alld 4 g mixture (50:50 by 1I't.)

8 57.6 17.4* 44.78 147.9 45.6*** 43.28 110.4 54.0** 43.68 ]08.4 31.9* ** 46.96 94.7 21.3*** 65.5

40.975.978.3

3 \.634.036.134.950.8

• Significant level of difference hetween means: a = P<O.IO; aa = P<O.05; aaa = P<O.OI.

818 ENVIRONMENTAL ENTOMOLOGY Vol. 2, no. 5

FIG. 2.-Numbers of females per stage of oogenesiscollected in suspended units having dichlorvos sugar-baitwith and without the attractant LursectT'I.

preference by specific age groups was indicated. Thedifference in age structure was primarily caused bypredominance of nulliparous and parous flies inoogenic stages 5 and 6 at the Wend (Fig. 3). Atthe time of this experiment, the number and sexratio in the collections did not differ from one end tothe other.Experiment IV. Effect of Bait PlacementA long the Cage Rows

The baitings conducted along the central cage rowsprovided a cross-section view of fly behavior as itrelated to the peripheral and interior zones of thepoultry houses. The number of flies collected perpan unit in the cage row experiment at Ranch PAwas greatest at the E and Wends of the rows, leastat the center, and increased slightly near the centeraisle (Fig. 4). The proportion of females per sta-tion in this experiment was inversely proportional tothe sample size. A test for independence of both thesample size and the female proportions per stationfrom the end to center aisles of the E and W sec-tions showed no significant differences between the2 sections. Within the 5 stations of the E half ofthe ranch, the proportions of females per physiologi-cal age were determined for each station, and sig-nificant (P<O.05) independence in the proportion ofage groups along the cage row was indicated.

Fig. 5 illustrates the spatial pattern of the agestructure of females collected along the cage rowof Ranch PA. Fly activity is clearly shown to begreatest at the E end where the exposure to lightcoming through the open end of the house wasmaximum. The age structure of the flies collectedat this station was dominated by the protein-search-ing age groups, N 3+4, P 3+4, and P 5+6. Thepreovipositional groups N 9+ 10 and P 9+ 10 in-crease in proportion to other groups toward the in-interior. The low number of females in age groupN 5+6 is unusual and should, in theory, be greaterthan age group N 7+8, which was documented bySmith (1968) as an uncommon group. However,

In ••• l •• = Oichlorvos Sugar Bait Alone

49.947.545.5

%females

]64.1±48.3 a'200.4±24.4 b2] 4.6±53.9 b

Mean no. house flies/unit

24 h48 h72h

CollectionperiOd

• Means bearing different letters significantly different from oneanother at P<O.05.

these dissections were done on flies collected in theE half of the house, and the results of the cornercollections and the end row collections (Fig. 4)shows that group N 5+6 had a prefence for theWend.

The numbers and proportion of males collectedper station are also greatest at the end of the rowand correspond to the abundance of age groupsN 5+6 and N 7+8, which are preferred by males(Adams and Hintz 1969).

The results of the cage row experiment at RanchMA are similar to that of Ranch PA. Number offlies collected per unit was greatest at the E end,dropped sharply, and gradually to the Wend. Theproportion of females was lower at the end stationsthan the neighboring stations, but an overall corre-lation of sex ratio and number of flies collected wasnot present as in the experiment at Ranch PA. Thisdiscrepancy between the results of Ranch MA andRanch PA could be due to the fact that the differ-ence in surface area studied was nearly 10-fold.Although the sample size showed distinct differencesin stations along the cage rows, significant inde-pendence of the proportion of age groups per stationwas not demonstrated (P>O.lO) by a chi-square test.

Fig. 5 illustrates the spatial patterns of age struc-ture derived from the cage-row collections of RanchMA. This house was small compared with that ofRanch PA, and the dominance of preovipositionalage groups in the interior is not so clearly defined.The protein-searching age groups dominated theends of the house, but the directional preferences ofnulliparous and parous age groups were in oppositedirection from each other. The N 3+4 group wasabundant in the E end but not the W, whereas theage groups P 3+4 and P 5+6 were abundant atboth ends. The relationship between age groups N5-8 (which included mating females) and high maleactivity did not appear so obvious in this experimentas that of Ranch PA.

A valid comparison can be made between theresults of the female age data from the corner col-lections (Experiment III) and cage-row collections(Experiment IV) on Ranch PA. A test for inde-pendence of age-group proportions between the cage-row and corner collections showed a highly signifi-cant difference (P<O.Ol). In addition, the averagenumber of flies collected per corner unit (388 flies!unit) was significantly greater than that collected

Table 2.-Elfect of exposure period on the number andsex of house flies collected in suspended units baitedwith dichlorvos sugar-bait plus attractant.

34 56 78grjQPorous

Oogenesis

- = Dichlorvos Sugor Bait 8 Attractant

12345678Nulliparous

Stage of

40

OJ>4:

c:::>

"-on.~ 30;;:::::::Jo:r: 20OJ"0EIf.,; 10z

October 1973 WILLSON AND MULLA: HOUSE FLY RESPONSE TO ATTRACTIVE BAITS 819

]::1(;. 3.-Influcnce of bait-station placement on thenumber of females collected per stage of oogenesis inhait units suspended at the end of cage row nearest thecorners and along the east and west sides of Ranch PA.

_West East-Cage Row Stations

'" 30"0

~ 20

~IO•.a.

FIG. 4.-Number and sex of house flies collected alongcentral cage rows of Ranch PA.

capability of the latter. The increase in flies col-lected was expressed in both sexes, and an explana-tion of this phenomenon is provided by analysis ofphysiological age structure of the females collected.The most prominent age group of females respond-ing to the attractant was nulliparous Group 3+4.This group corresponds to the "potential restingphase" which was found to be a stage at which thefemale house fly requires protein before ovariandevelopment can continue (Goodman et a1. 1968).Adams (1970) noted a decrease in area of thecorpus allatum during N 3+4 and P 3 to 5 whichimplied a decrease in the production of juvenilehormone during those particular stages, and as aresult, a pause in ovarian development. Therefore,the prime response of female house flies is duringa stage of oogenic development in which proteinrequirement must be satisfied before normal devel-opment can proceed. As a result, the volatile at-tractant, derived from proteinaceous material, luresa segment of the fly population that would haveignored the poisoned sugar-bait lacking the volatileattractant.

The increased response of stages N 9+ 10 andP 9+ 10 is possibly due to the attractant acting asan ovipositional lure. Larsen et al. (1966) foundthat house flies in the preovipositional period re-spond to odors eminating from suitable ovipositionalmedia. A brief field test using CSMA fly mediawith and without the attractant has demonstratedthat the attractant can stimulate additional oviposi-tion.

The added response of adult males to bait unitswith Lursect is difficult to explain. Laboratory ob-servations in a turntable olfactometer demonstratedthat females respond more to the attractant thanmales (Willson, unpublished data). Murvosh et a!.(1964) and Rogoff et al. (1964) reported that malehouse flies are attracted to dead virgin females, andthey related this behavior to the presence of a sexpheromone. Adams and Hintz (1969) reportedthat females with ovaries in stages 3 and 4 rarelymated, but thereafter mating steadily increased andmales preferred females with ovaries in stages 6-10.

,,\,,,,,,,,,,,,

Southeast

NortheastSouthwestNurthwest

1-2 :'-4 5-6 7-8 9-10 3-4 5-6 7-8 9-10Nulliparous Porous

Stage of Oogenesis

70

60

=

ooz \0Q)>

<t

~o~20

u..

.•...c: 4::J

"-f/)Q)

;;::\Q) 3

f/),

",

0 ,:I: ,Q) ,0 2 ,E ,<II ,

I.J... East'0

,,ci , , Westz , , ,cO I:> ,/«

along the cage rows (23 flies/unit). And, theproportion of females in corner collections (46%)was less than that of the cage-row collections(73% ).

DiscussionEfficacy of tire Attractant

Addition of the proteinaceous attractant to dich-lorvos sugar-bait clearly improved the fly-collecting

820 ENVIRONMENTAL ENTOMOLOGY Vol. 2, no. 5

Nulliparous females in age group 5+6 respond toLursect and may release sufficient sex pheromone toattract males. Therefore, male response to the at-tractant probably is due to both the volatile odor ofthe bait plus excitation by the dead females.

The age structure of flies baited by the attractantsugar-bait mixture would appear to be more repre-sentative of a natural population than that baitedby sugar-bait alone. Although sugar-bait alone doesnot attract protein-searching females, it mllst berecognized that the attractant in Lursect is volatileand may thus attract more protein-searching femalesthan the actual representation of that age group inthe field population.

Smith (1968) studied physiological age in rela-tion to the calendar time required for an adultfemale house fly to pass from one age group toanother. He found that the early stages of oogenesisand the preovipositional stage were relatively slowcompared with the rather quick development of thefollicle-elongation stages which would correspond toAdams' Stages 6 through 8. Suenaga (1969) alsostudied the calendar age of house flies per physio-logical age group and noted the seasonal differencesin the rate of gonotrophic development. The agecharts which he produced showed the early nullipar-ous stages to be more predominant than the latevitellogenic stages. Therefore, the predominance ofearly oogenic stages found in the flies baited by theattractant sugar-bait mixture coincide with t he ob-servations of Smith and Suenaga.

The data from exposure tests suggest that theprimary response occurs within the first 24 h, with

a decline in activity during the second 24 h, andalmost no activity during the third 24-h period.This decrease in the response may be due to sevcralfactors: (l) the attractancy of Lurscct declines onexposure (Mulla et al. 1973); (2) the attractancyof the bait and the effectiveness of the toxicantmay decline due to dead flies covering the bait; (3)the extreme climatic conditions may adversely affecteither fly activity or attractant longevity. Howevcr,the attractant has been obscrved to lure many flicson the 3rd day following an initial 48 h of coolclimate, and the number of flies collected has oftenreached as high as 1000 flies/survey unit. Ingeneral, it has been found that the bulk of the fliesare attracted during the first 48 h. The 72-h ex-posure period was adopted for population monitor-ing, because shorter periods require more frequcntfield trips, and the longer exposure period results inmicrobial decay of the collected fly samples.Effect of Bait Unit Placement

The importance of bait location for maximizingfly collection has been demonstrated. If one assumcsthat a feeding attractant has a limited range indrawing flies to the bait, then one must concludethat the collections obtained at various bait stationsare representative of the fly activity of a given area.The distinct patterns of numbers, sex, and age struc-ture obtained in this study suggest that each seg-ment of a house fly population exhibits a uniquepattern of spacial activity. Recently emerged andgravid females were fairly evenly dispersed alongthe cage rows of the poultry house, but protein-

3-4 5-67-8 9-10/3-45-6 7-8 9-10

Nulliparous I Parous

Stage of Oogenesis

/

Porous

Oogenesis

RANCH PA "c RA~CH MA::I.••..., 30..~0I

.!! 200E.....'9

100zoj

~

Nulliparous

Stoge of

1-2 3-4 5-6 7-8 9-10 3-4 5-67-8 9-10

10

'i:::I

8....••e..

6.~0x..'6

4E..•....'50z 2oj,.c(

/

FIG. 5.-Influence of bait station placement on the number of females collected per stage of oogenesis in panunits along cage rows of Ranch PA and in shidded cup units along cage rows of Ranch MA.

October 1973 WILLSON AND MULLA: HOUSE FLY RESPONSE TO ATTRACTIVE BAITS 821

searching and mating females were concentratedwithin distinct zones of activity. Such behavior offemale age groups corresponding with concentra-tions of male activity suggests existence of specificzones of mating activity. These zones of high flyactivity were areas where exposure to light wasgreatest. Such areas could be interpreted as the"border of shade and sunlight," which Davidson( 1962) recommended for bait-trapping house flies,However, such a generalization cannot be appliedto all situations because fly behavior is regulated bythe environmental conditions which vary with cli-matic changes and differ with the structural designof each ranch situation (Willson and Mulla, unpub-lished data). As a result, the sex ratio and agestructure patterns observed at Ranch MA did notcompletely coincide with that observed at RanchPAt and such variations between ranches would beexpected.

The implications of these findings upon the uscof bait for survey and control are important. Pre-sumably bait stations used for survey should samplea representative segment of the field population.The aggregation of age groups 3+4 and 5+6 com-bined with the even dispersion of age group 9+ 10complicates fly-population sampling. To obtain arepresentative sample. bait stations would have tohe situated to monitor fly populations in both thepotcntial areas of aggregated fly activity and evenlydispersed segments of the population. The aggre-gated fly activity would inevitably shift with chang-ing cnvironmental conditions. In the case of RanchPAt bait stations should he placed at the end of thecage rows to monitor aggregated fly activity andalong the cage rows to monitor the non aggregatedscgmcnts of the fly population. In addition, anadequate numher of stations is required to accountfor the directional preferences of various age groups.

Use of hait for fly control has often been re-ported as "scattered in areas of fly concentration"(Gahan et al. 1954. Mayeux 1954). But limitedattention has heen paid to spot treatment of specificareas (Keiding (965). On the basis of the resultsdescrihcd. the ctfect of a given amount of baitcould be maximized considerably by treating onlythose areas when lly activity is high. In the case ofchemosterilant baits (Meifert and LaBreque 1971),which are directed to specific age and sex groups,knowledge of peak areas of fly activity would bevery relevant. For example, at Ranch PA, mostfemales aggregate in the peripheral zones duringsome point of each oogenic cycle. As a result,restriction of hait application to the peripheral endsof the cage rows would limit treatment to less than10((,· surface area of the ranch. and the entire fe-male fly population would eventually be exposed tothe bait. Male and virgin female activity was con-tined mainly to the peripheral zones. and treatmentof an entire ranch by chemosterilant bait wouldconstitute waste of costly bait.

The examples cited here apply to a situation inwhich temperatures are generally less than 30·C.

High temperatures can change this situation by shift-ing fly activity in the interior zones (Willson andMulla, unpublished data). Therefore, fly activity ofany given ranch must be evaluated according to boththe size and layout of the ranch and the prevailingclimatic conditions.

REFERENCES CITEDAdams, T. S. 1970. Ovarian regulalion of the corpus

allatum in the house fly, Musca domestiea. 1. InsectPhysiol. ] 6: 349-60.

Adams, T. S., and A. M. Hintz. 1969. Relationship ofage, ovarian development, and the corpus allatum tomating in the house fly, Musca domestiea. Ibid. ] 5:201-15.

Adams, T. S., and M. S. MlIlla. 1967. The repro-ductive biology of Hippelates collusor (Diptera:Chloropidae). n. Gametogenesis. Ann. Entomo\.Soc. Am. 58: ]]77-82.

Anderson, J. R. 1964. Methods for distinguishingnulliparous from parous flies and for estimating theages of Fallllia callicularis and some other cyclorra-phous Diptera. Ann. Entomol. Soc. Am. 57:226-36.

Anderson, J. R., and J. H. Poorbaugh. 1964. Obser-vations on the ethology and ecology of variousDiptera associated with northern California poultryranches. J. Med. Entomol. I: 131-47.

Beroza, M., and N. Green. 1963. Materials tested asinsect attractants. USDA Agric. Handbook no. 239.148 p.

Brown, A. W. A., A. S. West, and A. S. I,ockley. 1961.Chemical attractants for the adult house fly. J.Econ. Entomol. 54: 670-4.

Davidson, A. 1962. Trapping houseflies in the ruralareas of Israel. Riv. Parassito\. 23: 61-70.

Derbeneva-Ukhova, B. P. 1935. The influence of theconditions of adult feeding on the development ofthe ovaries of Musca domestiea, Med. Parasito\. 4:394-403.

Frishman, A. M., and J. G. Matthysse. 1966. Ol-factory responses of the face fly Musca autulllllalisDe Geer and the house fly Musca domestieu Linn.Cornell Univ. Agric. Exp. Stn. Memoir no. 394.91 p.

Gahan, J. 8., H. G. Wilson, and W. C. McDuffie. 1954.Insecticide baits. J. Agric. Food Chern. 2: 425-8.

Goodman, T., P. E. Morrison, and D. M. Davis. 1968.Cytological changes in the developing ovary of thehouse fly fed milk and other diets. Can. 1. Zool.46. 409-21.

Howard, L. 0., and R. H. Hutchinson. 1917. TheHouse-Fly. USDA Farmers Bull. 851. 23 p.

Keiding, J. 1965. Observations on the behavior of thehouse fly in relation to its control. Riv. Parassito1.26: 45-60.

Keller, J. c., H. G. Wilson, and C. N. Smith. 1956.Bait stations for the control of house flies. 1. Econ.Entomol. 49: 751-2.

Larsen, J .R., R. E. Pfadt, and L. G. Peterson. 1966.Olfactory and oviposition responses of the house flyto domestic manures, with notes on an autogenousstrain. Ibid. 59: 10-15.

Mason, H. C., R. T. Guest. J. S. Steel, Jr., and R. T.Kwietneiak. 1971. Bait units with lindane for sup-pression of Drosophila in tomato field plots. Ibid.64: 1216-9.

822 ENVIRONMENTAL ENTOMOLOGY Vol. 2. no. 5

Mayeux, H. S. 1954. Granular insecticidal baitsagainst flies. Fla. Entomo1. 37: 171-90.

Meifert, D. W., and G. C. LaBrecque. 1971. Inte-grated control for the suppression of a populationof housefties, Musca domestica 1.. J. Med. Entomol.7: 268-73.

Morrill, A. W. 1914. Experiments with house-fly baitsand poisons. 1. Econ. Entomol. 7: 268-73.

Mourier, H. 1964. Circling food-searching behavior ofthe house fly (Musca dumestica L.) Vidensk. Medd.Dan. Naturhist Foren. Kjobenhaun. 127: 181-94.

Mulla, M. S., Y. Hwang, and H. Axelrod. 1973. At-tractants for synanthropic flies. 3. Evaluation, de-velopment, and formulation of attractive baitsagainst Hippe/ates col/usor. 1. Econ. Entomol. 73:1089-94.

Murvosh. C. M., G. C. LaBrecque, and C. N. Smith.1964. Sex attraction in the house fly, Muscadomestica L. Ohio J. Sci. 65: 68-71.

Rogoff, W. M., A. D. Beltz, J. O. Johnsen, and F. W.

Plapp. 1964. A sex pheromone in the house fly,Musca domestica 1.. J. Med. Entomol. 5: 1-4.

Smith, T. A. Comparison of known age with physio-logical aging in the adult female house fly. Mu,\'cadomestica 1.. J. Med. Entomol. 5: 1-4.

Suenaga, O. 1969. Age grouping method by ovariolechanges following oviposition in females of Muscadomestica l'icillll and its application to field popula-tions. Trop. Med. 11: 76-90. [In Japanese; Englishsummary.]

Wiesmann, T. 1960. Untersuchungen liber die Sinncs-funktionen der Antennen von Alu.ITll domi'slica L.im Zusammenhang mit dem Koderproblem. [Studiesof the sensory functions of the antennae of M.domestica in connection with the problem of baits.]Mitt. Schweiz. Entomol. Ges. 33: ]21-54. Rev.Appl. Entomol. (8) 50: 210.

Willson, H. R. and M. S. Mulla. 1973. Bait units forcollection of house flies. Environ, Entomol. ::!:724-26.