Title: Reproductive biology of the lesser cornstalk borer, Elasmopalpus Lignosellus (Zeller) (Lepidoptera: Phycitidae)
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00097814/00001
 Material Information
Title: Reproductive biology of the lesser cornstalk borer, Elasmopalpus Lignosellus (Zeller) (Lepidoptera: Phycitidae)
Physical Description: 97 leaves : ill. ; 28 cm.
Language: English
Creator: Stone, Karl J
Copyright Date: 1968
Subject: Lepidoptera   ( lcsh )
Beneficial insects   ( lcsh )
Insect, Pests   ( lcsh )
Entomology and Nematology thesis Ph. D
Dissertations, Academic -- Entomology and Nematology -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: by Karl Johnson Stone.
Thesis: Thesis (Ph. D.)-- University of Florida, 1968.
Bibliography: Includes bibliographical references (leaves 88-94).
Additional Physical Form: Also available on World Wide Web
General Note: Typescript.
General Note: Vita, Karl Johnson Stone, 1935-
 Record Information
Bibliographic ID: UF00097814
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000433933
oclc - 37525914
notis - ACJ3628


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I greatly appreciate the advice and criticism offered by Dr. T. J. Walker,

chairman of my supervisory committee, during the research and preparat'"n of the


Appreciation is gratefully extended to Dr. L. A. Hetrick and Dr. J. T.

Creighton, Department of Entomology; Dr. D. B. Ward, Department of Botany;

Dr. G. C. LaBrecque, United States Department of Agriculture, Entomology Re-

search Division; and Dr. H. K. Wallace, Chairman of the Department of Zoology,

who served as members of the supervisory committee.

Appreciation is extended to Dr. W. G. Eden, Chairman of the Department

of Entomology for providing assistants who helped maintain the insect colony.

Special thanks is expressed to Mr. J. Beckner, Department of Botany for his

assistance in botanical nomenclature, and to Mr. P. U. Roos for assistance in

translating French and German material.

Sincere gratitude is extended to my wife for her generous assistance, patience,

and constant encouragement Involving long hours and many sacrifices.



ACKNOWLEDGEMENTS. . ...... . . ii


LIST OF FIGURES .. ........ .... vi

INTRODUCTION ................. 1

REVIEW OF LITERATURE .. .. . . . . 3

General References. ............... 3
Host Plants . . . .


Rearing Techniques. . . . . . 12
General Methods . . 12
Aberrant Pupae. . . 19
Other Materials and Methods . . . . .. 21


Morphology of the Reproductive System . . .. ... 22
Materials and Methods. .... . . . . 22
Results and Discussion . . .. 22
Male ............... 22
Female .. .. .. ....... .. . 26
The Spermatophore . .. 29
Materials and Methods. . . . . . . 31
Results and Discussion . . 31
Primary Simplex and Spermatophore Color . . .. 33
Materials and Methods. .. . . . . ... 33
Results and Discussion . . . . . . 34
Egg Development and Position Relative to Age . . . 35
Materials and Methods. . . ... . . 37
Results and Discussion. . . . . 37

Morphology of the Tympanic Organ .. . 39
Materials and Methods .. 40
Results and Discussion . ... . 40


Mating Cage Conditions. .. . . . 45
Materials and Methods. . . . . . .. 45
Results and Discussion . . .... 46
Mating Behavior. . . 48
Materials and Methods. . . 49
Results and Discussion .... ....... . 50
Influence of Additional Females on Male Mating Frequency 54
Materials and Methods. ........ .. 54
Results and Discussion . .. .. 55
Influence of Age on Mating . .. . 55
Materials and Methods. 56
Results and Discussion .... . 56
Influence of Male Antennectomy on Mating .. 56
Materials and Methods . . . . ... 58
Results and Discussion . . 58
Longevity of Virgin and Mated Moths, Spermatophore Passage and
Acceptance, and Fecundity .. 58
Materials and Methods. . . .. 59
Results and Discussion . . 60
Time of Oviposition. . . . 76
Materials and Methods. .. . . . 77
Results and Discussion. .. 77
Response of Adults to Sound .. 77
Materials and Methods. . . . 80
Results and Discussion . . 82

SUMMARY ....... ........... 85




able Page

1 Reported host plants of the lesser cornstalk borer.. ... . 6

2 Composition of medium for lesser cornstalk borer larvae. ... 16

3 Color fluid in the 1st secretary area of the primary simplex of 3-
day-old mated and unmated lesser cornstalk borer males at dif-
ferent periods of the day following mating the previous night. 36

4 Cage conditions and spermatophores passed by 2-day-old fed and
unfed lesser cornstalk borer adults, tested for 4 nights in 40-dr
vials, 1 pair per vial, 22 replicates per test. ..... . . 47

5 Longevity of lesser cornstalk borer adults. . . .. 61

6 Spermatophore passage and acceptance during the lifetime of various
Lepidoptera. . . .... .. . . . 63

7 Fecundity of the lesser cornstalk borer . 69

8 Lesser cornstalk borer females showing 2 or more variations from
basic population oviposition patterns. ... .. 73


gure Page
1 Cages used in rearing technique. A. Mating-oviposition cage.
B. Rearing cage. 14

2 VeniTal view of terminal pupal abdominal segments of the lesser
cornstalk borer. . . ... . . .. 18

3 Reproductive system of the male lesser cornstalk borer. ... 25

4 Reproductive system of the female lesser cornstalk borer. . 28

5 Spermatophore of the lesser cornstalk borer. . . .. 32

6 Egg development and position in the reproductive tract of lesser
cornstalk borer virgin females relative to age. . .. 38

7 External anterior view of the first abdominal segment of the lesser
cornstalk borer moth illustrating the tympanic organs on the ex-
cised abdomen. .............. . 43

8 Internal lateral view of the right tympanic organ of the lesser
cornstalk moth with the lateral wall of the tympanic sac removed 44

9 Percent mating of 1-6-day-old lesser cornstalk borer adults caged
for day . .. 57

10 Mated lesser cornstalk borer male longevity and spermatophores
passed ... ............. .. 64

11 Mated lesser cornstalk borer female longevity, ovipositian period,
fecundity, and spermatophores accepted.. . ... 65

12 Total number of spermatophores passed per day by 25 lesser corn-
stalk borer males, number of males after day 14 as indicated. . 67

13 Average numbers of eggs laid per day by 25 lesser cornstalk borer
mated females, number of females after day 12 as indicated. 71


Figure Page
14 Diurnal and nocturnal response of lesser cornstalk borer adults
to various amplitudes and frequencies. . . . .. 84


The lesser cornstalk borer, Easmopalpus lignosellus (Zeiler), is an important

pest of crops in Florida, causing considerable damage to corn, soybeans, peanuts,

sugar cane, field peas, southern peas, and rye. The moth is widely distributed

throughout the tropical and temperate regions of the New World, including the

southern half of the United States from California to the Carolinas, north on the

East Coast to Massachusetts, and south thru Central America and South America to

Argentina, Chile, and Peru (Heinrich, 1956).

Damage to crops in Florida occurs primarily in areas with muck or sandy soils

(Strayer, J. R.1 1968. Personal communication.). Luginbill and Ainslie (1917)

and Lyle (1927) found that damage usually seems greater on thin sandy soils in South

Carolina, Florida, and Mississippi. King et al. (1961) in Texas reported damage is

especially severe during drought periods. Leuck (1966) in Georgia reported larvae

damage seedlings during drought and when late plantings are followed by hot dry

periods. Wide-spread infestations have led to several insecticidal investigations.

However, little is known about the moth's reproductive biology. Basic research

in this area was facilitated by rearing the insect in the laboratory and examining the

reproductive morphology with respect to structure and changes occurring when moths

1 Assistant Extension Entomologist, Institute of Food and Agricultural Sciences,
University of Florida.


mated or aged. In addition the morphology of the tympanic organ is discussed.

Behavioral studies included mating behavior and various factors which influ-

enced this activity: cage conditions, additional females on male mating frequency,

age, and male antennectomy. The longevity of virgin and mated moths, sperma-

tophore passage patterns, and fecundity were studied, as well as time of ovipo-

sition. Lastly, the response of adults to sound was observed.

The above information may facilitate studies on the effects of chemosterilants,

antimetabolites, and predator and parasite relationships.


General References

The literature contains considerable research on insecticidal control of the lesser

cornstalk borer, but little is known about its biology. Below are the papers that deal

with reproductive biology and rearing methods.

Luginbill and Ainslie (1917), using moths from South Carolina and Florida, dis-

cussed rearing methods and mating cage conditions, as well as longevity, fecundity,

and time of mating. Sanchez (1960), Dupree (1965), Leuck (1966), and Calvo (1966)

discussed similar factors with moths from Texas, Georgia, and Florida.

Host Plants

The lesser cornstalk borer attacks many weeds and crops, especially legumes and

grasses, throughout the southern half of the United States (King et al., 1961).

Table 1 lists 62 host plants of the lesser cornstalk borer. The following 14

Families are represented: Chenopodiaceae, Convolvulaceae, Cruciferae, Cucur-

bitaceae, Cyperaceae, Gramineae, Iridaceae, Leguminosae, Linaceae, Malvaceae,

Pinaceae, Rosaceae, Rutaceae, and Solanaceae. Confusion in the taxonomy of culti-

vated plantsandcommon names complicated compilation of the list, and in some cases,

the same host is listed under different common names to indicate common usage in

different parts of the country. In such cases, e.g. black-eyed beans = black-eyed

peas, the host is counted only once in the total count of hosts. Where varietal

names are available, each host is counted once. Scientific names were obtained

fiom standard references (Bailey, 1949; Fernald, 1950; Hitchcock, 1951) and

Hill's (1937) paper on cultivated sorghums.

Most authors consider the pest a subterranean feeder, but some reports suggest

feeding on the aerial parts of plants. Similar feeding behavior of other species

may have misled workers and confused host records. For instance, the phycitid

moth, Ufa rubedinella (Zeller) (=Elasmopalpus rubedinellus (Zeller)), redescribed

by Heinrich (1956) was reported feeding on leaves and fruits of lima beans and

black-eyed peas in Florida (unpublished records, Florida Department of Agriculture,

Division of Plant Industry, 1944-1945). The larva webs debris in a manner similar

to the lesser cornstalk borer, but the insect has not been reported in the DPI files

since 1945. Unidentified pyralid larvae were reported on peach seedlings by Dekle

(1965) with the characteristic sand-debris subterranean tunnels of E. lignosellus;

however, the tunnels also extended up the stems and over leaves.

Table 1 Notes

a U.S. Dep. Agr., 1952-1968
b Reynolds, Anderson, and Andres, 1959
c Chittenden, 1900
d Chittenden, 1903b
e Howard, 1900
f Vorhies and Wehrle, 1946
g Isely and Miner, 1944
h Wilson and Kelsheimer, 1955
i Kelsheimer, 1955
j Bissell, 1945
k Bissell, 1946
I Lyle, 1927
m Luginbill and Ainslie, 1917
n Sanchez, 1960
o Riley, 1882 (as cited by Luginbill and Ainslie, 1917.)
p Riley, 1882a
q Riley, 1882b
r Dempsey and Brantley, 1953
s Forbes, 1905
t Webster, 1906
u Bissell and Dupree, 1947
v Leuck, 1966
w Chittenden, 1903a
x Heinrich, 1956
y Dupree, 1964
z King, Harding, and Langley, 1961
aa Arthur and Arant, 1956
bb Walton, Matlock, and Boyd, 1964
cc Cunningham, King, and Langley, 1959
dd Harding, 1960
ee Calvo, 1966
ft Cowart and Dempsey, 1949
gg Ash and Bibby, 1957
hh Stahl, 1930

Table 1.-Repcrted host plants of the lesser cornstalk borer

Common Name Scientific Name Localities References















Medicago sativa L.

Hordeum vulgare L.

Phaseolus sp.

Vigna sinensis
(L.) Endl.

Phaseolus vulgaris L.
var. humilis Alef.

Phaseolus limensis

Phaseolus vulgaris L.

Phaseolus vulgaris L.

Ariz., Kans., a.

Calif. b.

Ala., Ariz., Ark., a,b,c,d,e,
Calif., Dela., f,g,h,i,j,
Fla., Ga., Md., k,l.
Miss., Mo., N.C.,
Okla., S.C.,
Tenn., Tex., Va.

N.C. a.

Calif. a.

Tex. a.

Okla. a.

Ala., Fla., Ga., a.
Md., S.C., Va.

Tex. a.

Ariz. a.

Fla. a.

Ala., Ark., a.
Conn., Ga., Md.,
N.C., Okla.,
S.C., Tenn., Va.

Calif., Ga. a.

Ala. a.

Beta vulgaris L.


Table 1 Continued

Common Name Scientific Name Localities References

Cabbage Brassica oleracea L. Fla. a.
var. capitata L.

Cane, Saccharum officinarium Fla. m.
Japanese L.

sugar Fla., La., Miss. a,I.

Cantaloupe Cucumis melo L. var. Calif., Tex. a,n.
cantalupensis Naud.

Chufa Cyperus esculentus L. Fla. m.
var. sativus Boeckl.

Citrus Citrus sp. Fla. a.

Clover, Trifolium incarnatum L. Ga. j.
crimson var. elatius Gibeli
& BeIT-

Clover, Trifolium repens L. Fla. a.
White Dutch

Cole Brassica sp. Va. a.

Corn Zea mays L. Ala., Ark., a,b,f,g,h,
Ariz., Calif., i,j,I,m,n,
Conn., Fla., Ga., o,p,q,r,s.
II., La., Mass.,
Md., Miss., N.C.,
Okla., S.C., Tex.,

field Fla., Ga., Tex. a.

silage Ga. a.

Corn, Sorghum vulgare Pers. Okla. a.
broom var. technicum
(Koern.) Fiori &

Common Name















Table 1 Continued

Scientific Name L

Sorghum vulgare Pers. C
var. caffrorum (Retz.)
Hubbard &Rehder

Zea mays L. var. A
rugosa Bonaf. F

Hibiscus gossypium L. C

Vigna sinensis A
-(LTEnd-. F


Linum usitatissimum L.

Alopecurus pratensis L. A

Gladiolus sp. F

Echinochloa crusgalli A
(L.) Beauv.

Cynodon dactylon C
L. Pers.

Panicum texanum Buckl. T

Digitaria sanquinalis A
(L.) Scop. F

Sorghum halepense A
(L.) Pers. F

Cyperus esculentus L. C

Digitaria decumbens F



riz., Calif.,


la., Ariz., Ark.,
la., Ga., Miss.,
J.C., Okla.,
.C., Tex., Va.




:alif., Ga.


krk., Calif.,
la., Ga., Tex.,

riz., Calif.,
la., Miss.,
)kla., Tex.

alif., Fla.

















Table 1 Continued

Common Name
















Table 1 Continued




Scientific Name

Chloris gayana Kunth

Lolium sp.

Sorghum sudanense
(iper) Stapf

Cyperus sp.

Eleusine indica (L.)

Aegilops sp. ?

Cyamopsis psoralioides

Sorghum vulgare Pers.

Robinia pseudoacacia L.

Lupinus augustifolius L.
var. 'rancher'

Lupinus hirsutus L.

Panicum miliaceum L.

Sorghum subglabrescens
(Sleud.) A. F. Hill

Avena sativa L.

Avena barbata Brat.
or A. fatua L.

Local i ties





Ga., S.C.



Ariz., Tex.

Fla., Ga.


La., S.C.

Ariz., Tex.

Ala., Calif.,
Miss., S.C., Tex.














Table 1 Continued

Common Name Scientific Name Localities References





Cyperus papyrus L.

Prunus persica
(L.) Batsch

Arachis hypogaea L.

Pisum sativum L.

Pisum sativum L.
var. arvense (L.) Poir.

Vigna sinensis

Capsicum frutescens L.

Pinus toeda L.

Ipomoea batatas Lam. Calif., Fla., Ga.

Ala., Ariz.,
Calif., Fla.,
Ga., Miss.,
N.C., Oklo.,
S.C., Tex.

Ala., Ariz.,
Ark., Calif.,
Fla., Ga., N.C.,
Okla., S.C., Tex.




Ala., Calif.,
Fla., Ga., Miss.,

Ala., Ariz.,
Calif., Ga., Tex.



Dela., Fla., Ga.








southern table















Common Name














Fragaria virginiana Ala., Ark.,
Duch. Calif., Fla., Md.,
N.C., N.Y.,
Tenn., Va.

Lycopersicon esculentum Fla., N.C., Tex.

Brassica napus L. Ala., Ariz.,
FlI., Ga.

Vicia sp. T-.

Triticum aestivum L. AlI., Fia.,
Ci I ,. T,,..

Table 1 Continued

Scientific Name

Oryza sativa L.

Secale cereale L.

Sorghum vulgare Pers.
var. vulgare

Sorghum vulgare Pers.
var. vulgare

Sorghum almum Parodi

Glycine max (L.) Merr.

Matthiola sp.


Fla., La.

Fla., Tex.

Ariz., Calif.,
Fla., Ga., La.,
Miss., Okla.,
S.C., Tex.

Ala., Ariz.,
Fla., Miss.,
N.C., Okla.,


Ala., Ariz.,
Ark., Fla., Ga.,
La., Miss., N.C.,
S.C., Tex., Va.
















Rearing Techniques

General Methods

Moths collected by Calvo (1966) in light traps near Gainesville, Florida,

were the original stock for this investigation. Individuals from this stock were

used to start a colony which was maintained for 7 months to establish a large

colony before experimentation began. The colony was maintained for 27 months

thereafter, representing a total of approximately 32 generations.

Several workers reared the insect thru its life history for 1 or 2 generations

(Luginbill and Ainslie, 1917; Sanchez, 1960; King et al., 1961; Dupree, 1965;

Leuck, 1966). Calvo (1966) reared several generations on a modification of

Berger's (1963) diet for Heliothis sp. Larvae were reared individually in vials.

Macerated corn seedlings were added to the diet every 3rd generation to avoid

pupal aberrations. Calvo (1966) collected eggs laid on paper thru screen topped

cages -- the method adopted here.

Transparent plastic containers, 10 x 10 x 7 1/2 cm deep were used as mating-

ovipasition cages (Fig. 1 A). Ten male and ten female pupae were placed in each

cage. A 14 x 18 mesh per inch galvanized screen stapled to a rim of wooden strips

was placed over the cage mouth. Two percent sucrose solution was supplied in a

wide-mouth pipette and soft rubber bulb (total capacity 4 ml) placed thru a hole



in the screen. This supply normally lasted 12 days. Immediately below the pipette

was a dish 4 cm in diameter, held in place by masking tape in a rear floor corner.

The dish trapped sugar solution that might drop from the pipette. If spilled solution

coated the pupae, the adults could not emerge properly. Four mating-oviposition

cages were prepared on each of 5 days during the week.

Each cage with pupae was numbered and put in a culture room at 47 4 10 C,

30-50% relative humidity, and daily photoperiod of 13 hr light. The pipette bulb

was squeezed daily to release the air bubble that formed at the bottom, thus mak-

ing the solution available to the emerged moths. After 1 of each sex had emerged,

a paper sheet identified with the corresponding cage number was placed daily over

the screen top. One corner of the egg sheet was folded upward to allow space for

the protruding pipette bulb. The plastic cage top was placed diagonally over the

sheet to hold it down. Eggs were laid on the sheet through the screen and were

readily visible on the paper. After 7 of each sex emerged, this procedure was con-

tinued for 9 more days.

Egg sheets were removed daily and set aside on trays in the culture room for

24 hr. Egg color was used to differentiate between fertile and sterile eggs, since

fertile eggs turned from cream white to red, while sterile eggs remained cream color-

ed or turn red at 1 end only. The sheets were arranged in order on the basis of

mating cage number and those with less than 30 eggs or more than 10% sterile eggs

were discarded. To preserve genetic variability, the following system was used.

Sixteen sheets were selected from the remaining egg sheets and divided into 4 groups

of 4 each, with the lowest numbered sheet going to the 1st group, the next highest

to Ihe 2nd group, and so on until distributed. Then 25 fertile eggs were cut from


Fig. 1.-Cages used in rearing technique. A. Mating-oviposition cage.
B. Rearing cage.

each sheer and each group was put into a transparent plastic rearing cage. This

cage (Fig. 1 B), 12 1/4 x 17 1/4 cm by 6 cm deep was filled to about 12 mm depth

with medium, modified from Berger (1963).

A duo-speed Waringblender, model 1002, with 1 liter containers was used

in media preparation. A blend was mixed in the order listed in Table 2. Blending

was at low speed thru and including addition of alphacel. Previously measured

ingredients were added without pause to avoid a highly viscous mixture. While the

agar cooled to about 410 C after removal from the autoclave (about 3 min, running

cool tap water over the flask containing the agar), the blender was run continuously.

The agar was then added with the blender running at high speed for the remaining

blending. The total mixing process took 6-8 min.

Medium prepared the day before use and placed under refrigeration was best,

as fresh medium had somewhat more moisture than optimum. Any moisture that con-

densed on the sides of the container when it was removed from the refrigerator was

wiped off. Otherwise, the water would cover the medium and ultimately kill the

eggs, young larvae, or both. About 250 ml of sifted, white, sterilized sand was

poured down the long axis of each cage, and the sand ridge was leveled off, leav-

ing the medium free of sand along the cage sides. The papers with 100 eggs of each

group were placed on the sand ridges. Next a sterilized paper towel was placed

over the cage rim, and a screen top was placed firmly over the towel. The screen

top was made by cutting out the center of the plastic container top and replacing

it with screen of the same mesh as used for the mating cages. The towel reduced

evaporation and the screen top prevented larval escape. To reduce evaporation

further, a 1.3 cm thickness of sterilized cellucotton was put over the screen top and

held on with a large rubber band.

Table 2.-Composition of medium for lesser cornstalk borer larvae.

Distilled water 190.0 ml

KOH, 22.5% 4.3 ml

Casein, vitamin free 40.0 g

Wesson's salts 8.5 g

Sucrose 22.7 g

Formaldehyde, 10% 3.1 ml

Solution of: 7 g methyl p-hydroxybenzoate and

7 g sorbic acid in 50 ml 95% ethyl alcohol 12.5 ml

Wheat germ 25.6

Alphacel hydrolyzedd purified cellulose, powder) 4.3 g

Agar, dissolved in 515 ml water 21.3

Vitamin diet fortification mixturea 8.5 g

Ascorbic acid 13.6 g

Streptomycin sulfate (700 micrograms/ml) 118.0 mg

a Nutritional Biochemicals Corporation, Cleveland, Ohio

After 21 days, the cage was opened, and the cellucotton, paper towel, and

medium were removed. The screen top was replaced and used as a sieve for rapid

separation of cocoons from the sand. The cocoons were hand picked from the re-

maining debris and placed in a small household sieve.

The sieve with the cocoons were dipped in dilute Chlorox solution (1 part

chlorox to 1 part water) for 45-60 sec and agitated to dissolve the silk and free

the pupae (Bartlett and Martin, 1945). After rinsing the pupae in water, the pupae

were dipped for 15-30 sec in 60% isopropyl alcohol. The pupae sank and the lar-

val exuviae were floated off. The pupae were spread on a paper towel to dry.

Separation plus extraction took about 15 min per cage.

After extraction and drying, the pupae were sexed by examining the terminal

abdominal segment (Fig. 2). Sexing was completed in 15 min per cage. Pupae

were then selected for mating-oviposition cages. No more than 5 pupae and no

more than 3 of 1 sex from a given rearing cage were put in 1 mating-oviposition

cage. Pupae at the same developmental stage, judged by color, were placed in a

given mating-oviposition cage so that adults would emerge about the same time.

Four cages per day 5 days a week were prepared, numbered, and put in the culture


Females began ovipositing on the 2nd night after emergence. During the 9

days that a mating-oviposition cage was kept, about 80% of the eggs that would

be laid were deposited on the egg sheets. Colony daily egg production was about

5000. Duration of egg, larval, or pupal stages was not recorded as production of

adults was the primary goal. Total time from egg deposition to adult emergence

was 24-28 days. Larvae consumed about 1/10 of the media. Production was low


1 mm

Fig. 2.-Ventral view of terminal pupal abdominal segments of the lesser
cornstalk barer

for the 1st few generations, but after a few generations, 60 to 80 pupae were ob-

tained per cage.

The average duration from egg to adult, 26 days, was as short or shorter than

results reported to date. Luginbill and Ainslie (1917) in South Carolina recorded

38.5 days for the spring generation, and 64.6 days for the fall generation under

unspecified laboratory conditions, feeding larvae cowpea leaves. Spring temper-

atures ranged somewhere between 80-900 F diurnally and reached 800 F noctur-

nally. Sanchez (1960) in Texas reported 24.3 days during August, and 46.3 days

during September-October, feeding larvae peanut roots. Eggs were exposed to

70-1000 F. Larvae were exposed to the following average daily minimum and

maximum temperatures: June, 77 and 92.30 F; July, 79.5 and 930 F; August,

79.5 and 94.50 F; September, 74 and 89 F. Pupae were exposed to temperature

ranges between the following minimum and maximum temperatures: July, 76-1000

F; August, 66-1020 F; September, 64 and 980F. No temperature ranges were

mentioned for October. King et al. (1961) relied heavily on Sanchez for data and

gave little detail on methods. Dupree (1965) in Georgia recorded 47.8 days and

55 days during June-September in 1957 and 1958, respectively, feeding larvae

foliage and stem sections of seedling southern peas. Average minimum and maxi-

mum temperatures were 66.6 and 86.40 F in 1957, and 66.8 and 88.20 F in 1958.

Leuck (1966) in Georgia reported 32.8 4 2.8 days, feeding larvae soybeans or

cowpea leaves. Monthly mean minimum temperatures ranged from 57.4 and 72.70

F, monthly mean maximum 79.7 and 96.20 F.

Aberrant Pupae

Calvo (1966) found after rearing 3 successive generations, a small but unspecified

percentage of pupae appeared with poorly developed wing pads and light scleroti-

zation over the pupal 3rd and 4th abdominal segments posterior to the wing pads.

He found that the addition of macerated corn seedlings to the diet every 3rd gen-

eration eliminated pupal aberrations.

To determine the percent pupal aberrations and percent successful emergence

from aberrant pupae occurring with my rearing technique after 23 generations, the

following experiment was conducted.

Groups of pupae extracted on each of 6 days were examined. Aberrant pupae

were described as below and place in numbered 4-dr vials, and the vials with pupae

were placed in the culture room until adult emergence or death. Dead pupae be-

came discolored and shriveled. Normal pupae not used in colony maintanence were

used as controls and were handled in the same manner but not numbered.

All aberrations were on the pupal venter. These 4 categories were recognized:

(A) a lightly sclerotized area between the 3rd and/or 4th abdominal segment and

the wing pads and appendages; (B) a lightly sclerotized area between the 3rd and/or

4th abdominal segment and 1 or more appendages but not wing pads; (C) a lightly

sclerotized area between 2 or more appendages or between a wing pad and append-

age; and (D) 1 or more bright green appendages in an otherwise uniformly colored


Of 1721 pupae extracted, 5% of the male and 6% of the female pupae had

aberrations. Fifteen percent of aberrant pupae exhibited 2 or more aberration types.

Seventy-two percent of the males and 84% of the females emerged successfully, i.e.,

with wings fully expanded and with normally formed appendages. In the controls,

93% of the males and 92% of the females emerged successfully.

The low percent pupal aberrations and the high percent successful emergence

from aberrant pupae indicated the rearing technique was adequate.

Other Materials and Methods

Specific materials and methods are outlined under the appropriate sections be-

low. However, a few general procedures that were used in several experiments

are mentioned here.

Pupae not used to maintain the colony were placed in 4-dr 20 x 70 mm glass

shell vials, each with a small wad of cotton, and the vials were stoppered with

cotton plugs. When moths emerged, the cotton wad was saturated with 2% sucrose

solution. Adults were used the same day they emerged or were held in the 4-dr

vials until they reached an age desired for experimentation.

In experiments involving mating and longevity of virgins, moths were placed

in 4.7 cm x 8.5 cm 40-dr clear plastic vials. A wad of cellucotton was placed

in the vial bottom and was saturated with 2% sucrose solution. The vial mouths

were closed with squares of cellucotton 1/2 mm thick held in place with rubber

bands. The vials with moths were then placed vertically in enameled pans and the

pans with vials were placed in the temperature-controlled culture room. In experi-

ments in which the moths were held for more than 4 days, clean vials and saturated

cellucotton wads were provided daily.

All experiments were conducted in the same controlled temperature room at

47 +- 1 C, 30-50% RH, and a daily photoperiod of 13 hr light beginning at 7:00


With all morphological drawings, a stereoscopic microscope with an eyepiece

grid was used in making measurements.


Morphology of the Reproductive System

In order to fully understand certain aspects of mating behavior, the internal

reproductive morphology of the lesser cornstalk borer needed examination. The

literature contains no reference to the subject. However, other workers have

examined several related species, which ore compared with E. lignosellus below.

Materials and Methods

Five 1-day-old adults of each sex were dissected in physiological saline con-

sisting of NaCI 8 gm, KCI 0.2 gm, CaCI2 0.2 gm, H20 to liter.

Results and Discussion


The mole reproductive systems of E. lignosellus and the phycitid species

Anagasta kuehniella (Zeller) (Mediterranean flour moth), Ephestia cautella (Walker)

(almond moth), Ephestia ellutella (HUbner) (tobacco moth), and Plodia interpunctella

(Htbner) (Indian-meal moth) (Norris, 1932) are very similar, but the ductus ejacu-

latorius simplex and cornutus of E. lignosellus differ from the others.

The unpaired ductus ejaculatorius simplex extends from the caudal end of the

ductus ejaculatarius duplex (Fig. 3, D.e.d) to the aedeagus (Fig. 3, A). In the

Noctuidae, Callahan (1958b) and Callahan and Chapin (1960) divided the duct



into a cephalad primary secretary region and a caudad cuticular region where sperma-

tophore precursors are molded. Later Callahan and Cascio (1963) divided the primary

secretary region into the Ist and 2nd secretary areas. Norris (1932) histologically

determined 4 secretary regions in the ducts of A. kuehniella, Ephestia spp., and P.

interpunctella, while Musgrave (1937) recognized 8 regions in A. kuehniella.

In E. lignosellus, 4 regions are present in the duct, based on exterior gross

morphology (Fig. 3). They are described below using the terminology of Norris

(1932) with the terminology of Callahan and Cascio (1963) in parentheses.

The 1st region, which appears to include the 1st 3 unpaired glands, (=2nd

secretary area of the primary simplex) extends approximately 11.5 mm (diameter,

0.15 mm) from the ductus ejaculatorius duplex (Fig. 3, P.s.2).

The 2nd region or 4th unpaired gland (=Ist secretary area of the primary sim-

plex) extends 2.0 mm (diameter 0.2 mm) (Fig. 3, P.s.1). The region is not as great-

ly inflated with respect to the 1st 3 unpaired glands in A. kuehniella, Ephestia spp.,

and P. interpunctella.

The 3rd region or ductus ejaculatorius is 4 mm long (Fig. 3, D.e). The in-

flated 4th region is the bulbus ejaculatorius (=cuticular simplex) (Fig. 3, B.e). The

elongated horns of the ductus ejaculatorius of A. kuehniella, Ephestia spp., and

P. interpunctella are replaced in E. lignosellus by 2 swollen structures in the same

position as the horns (Fig. 3, I.c), adjacent to the aedeagus (Fig. 3, A).

The cornutus of E. lignosellus is a slender curved tooth (Fig. 3, C) differing

from the thickened teeth of various shapes of A. kuehniella, Ephestia spp., and P.


The morphology of the testes of E. lignosellus is the same as in A. kuehniella,

Explanation of Fig. 3

Terminology mostly after Norris (1932)
Terminology after Callahan and Cascio (1963) in parentheses

A Aedeagus

A.g Acessory glands

B.e Bulbus ejaculatorius (of cuticular simplex) of ductus ejaculatorius simplex

C Cornutus

D.e Ductus ejaculatorius of ductus ejaculatorius simplex

D.e.d Ductus ejaculotorius duplex

E Endophallus

. c Inflated chambers of ductus eajculatorius (of cuticular simplex) of ductus
ejaculatorius simplex

P.s.1 (1st secretary area of the primary simplex) of ductus ejaculatorius simplex

P.s.2 (2nd secretary area of the primary simplex) of ductus ejaculatorius simplex

S.v Seminal vesicle

T Testes

V.d Vas deferens


B.e c "1 1 mm

Fig. 3.-Reproductive system of the mole lesser cornstalk borer


Ephestia spp., and P. interpunctella. Cholodkovsky (1884) recognized 4 groups of

Lepidoptera based on testes types: (A) testes completely separate and 4-lobed, as

in Hepialus; (B) testes separate but rounded and 3-lobed, as in Saturnia; (C) dis-

cernibly separate testes enclosed in a single scrotum, as in Lycaena; and (D) testes

fused and appearing as a single round organ in a common scrotum, as in Pieris. All

phycitid species previously mentioned belong to group D.


The female reproductive system of E. lignosellus differs in several details from

the phycitid species by Norris (1932).

The bursa copulatrix of the lesser cornstalk borer consists of a sac, the corpus

bursae (Fig. 4, C.b), and a neck, the ductus bursae (Fig. 4, D.b), and opens ex-

ternally andventrally thru the ostium bursae (Fig. 4, O.b) on the 8th sernite. The

corpus bursae bears a large dorsal and small ventral plate bearing approximately 25

and 53 teeth or signa respectively (Fig. 4, D.p.s and V.p.s), which project into

the corpus lumen and oppose each other. In P. interpunctella, the 3-8 sign are

arranged on the dorsal wall of the corpus, while A. kuehniella has 2-4 sign on the

ventral wall only.

The ductus seminalis in E. lignosellus (Fig. 4, D.s) is of uniform diameter for

its entire length and apparently lacks a bulla seminis. The duct enters the corpus

bursae at a projection on the caudal end of the corpus. In A. kuehniella, Ephestia

spp., and P. interpunctella the duct winds around the corpus bursae in close asso-

ciation with the corpus wall and opens into the corpus adjacent to the sign, about

1/3 the corpus length from the cephalad end.

The glandula receptaculi of E. lignosellus (Fig. 4, G.r) is an elongate simple

Explanation of Fig. 4

Terminology after Norris (1932)

A.g Accessory gland

C Calyx

C.a.g Common duct of accessory gland

C.b Corpus bursae

C.o Common oviduct

D.b Ductus bursae with longitudinally ribbed sclerolization

D.p.s Dorsal plate with signa

D.r Ductus receptaculi

D.s Ductus seminalis

G.r Glandula receptaculi

I.v Inflated part of vestibulum wall

L.a.g Lateral duct of accessory gland

L.o Lateral oviduct

M Membrane surrounding the bursae copulatrix and the ductus seminalis

O.b Ostium bursae

Ovar Ovariole

Ovip Ovipositor

R.a.g Reservoir of accessory gland

T.v Terminal vesicle

Va Vagina

Ve Vestibulum

V.p.s Ventral plate with sign


D.b D.r

C.o L.o

O.b--o .a.g R.c

Va L.ga.


1 mm

Fig. 4.-Reproductive system of the female lesser cornstalk borer

structure tapering caudally and leading to the coiled ductus receptaculi (Fig. 4,

D.r) which in turn opens into a hemispherical inflated portion of the dorsal ves-

tibulum wall (Fig. 4, I.v). In P. interpunctella, the gland is nearly always simple.

In A. kuehniella it is often bifurcated at the tip, and one branch may be shorter

than the other. In both species, the gland opens into a caudal sac, the recepta-

culum seminis, which leads to the ductus receptaculum.

The lesser cornstalk borer accessory glands (Fig. 4, A.g) are elongate struc-

tures leading to a series of convolutions that ultimately open into the oval-shaped

reservoirs (Fig. 4, R.a.g) which in turn open into narrow ducts leading to the

common accessory gland duct (Fig. 4, C.a.g). In A. kuehniella, Ephestia spp.,

and P. interpunctella, the reservoirs are elongate structures with the greater part

of the caudal lengths dilated.

The Spermatophore

During a successful mating, the Lepidoptera transfer sperm in a spermatophore

formed from secretions in the male ductus ejaculatorius simplex (Callahan, 1958b).

Even within families, the spermatophore shape varies greatly (Williams, 1941), and

formation and transfer mechanisms are sometimes highly complex (Callahan, 1958b).

A spermatophore of A. kuehniella, E. cautella, E. elutella, or P. interpunctella

consists of a rounded corpus with a narrow twisted collum ending in a frenum. Solid

horns on the frenum correspond exactly in number and arrangement with species

specific structures of the ductus ejaculatorius. The sperm escape thru an oval aper-

ture in the frenum with the aperture at the ductus seminalis entrance (Norris, 1932).

Petersen (1907) found that Lepidoptera with ductus seminalis apertures distal

on the ductus bursae produce spermatophores with long collums. Where the aperture


appears in the corpus bursae, collums are either short or twisted beside the sperma-

tophore corpus, as in Anagasta, Ephestia, and Plodia (Norris, 1932).

Williams (1941) divided the Heterocera into 3 groups based on spermatophore

communication in the female reproductive system: (A) spermatophores in direct

communication with the ductus seminalis, which are found in the majority of the

moths; (B) spermatophores communicating with a duct leading to a secretion filled

reservoir opening into the ductus seminalis which leads from the reservoir to the

vagina, which are found in some arctiids and tortricids; and (C) spermatophores

opening into the ductus bursae which extends to the vagina, which ore found only

in the primitive prodoxids.

Stitz (1901) believed the sign punctured the spermatophore, but Williams

(1938) believed spermatophores were dissolved by enzymes in the ductus bursae.

Callahan (1958b) stated that there is no evidence for either of these beliefs. He

felt Petersen's (1907) theory that the sign serve to hold the smooth plastic-like

spermatophore in place is probably correct.

The empty spermatophores in female potato tuberworm moths, Phthorimaea

operculella (Zeller), are forced anteriorly in the corpus bursae when multiple

mating occurs (Hughes, 1967). Several are found collapsed and nested within

each other, while the most recently deposited spermatophore occupied Ihe corpus

bursae posteriorly.

The purpose of this section is to present the spermotophore morphology of E.

lignosellus, its position in the corpus bursae, the probable mode of sperm escape

from the spermatophore, and the fate of empty specmatophores.

Materials and Methods

Five spermatophores representing Ist matings by both males and females were

dissected from females and placed in physiological saline. During dissections, the

spermatophore orientation in the corpus bursae was observed.

The spermatophores in multiple mated females were observed in moths taken

from 4 mating-oviposition cages. Thirty-two females had 2-5 spermatophores in

the corpus bursae.

Results and Discussion

The spermatophore is illustrated in Fig. 5. The frenum bears 2 small rounded

projections that seem to correspond to the inflated chambers on the male ductus

ejaculotorius (Fig. 3, I.c). The aperture thru which sperm escape is terminal and

between the 2 rounded projections.

The 2 toothed plates of the corpus bursae walls tightly hold the spermatophore

in place. The collum is twisted and pressed against the posterior lateral wall of

the corpus bursae, and the frenum with its aperture is in direct contact with the

ductus seminalis. Thus the lesser cornstalk borer belongs to Williams' (1941) group


As in the potato tuberworm moth (Hughes, 1967), when multiple mating occurs,

empty spermatophores are forced anteriorly in the corpus bursae flattening and/or

nesting into one another. The most recently deposited spermatophore is held tightly

between the 2 plates of signa, which seems to support Petersen's (1907) theory of

signa function. No spermatophores were punctured and none showed evidence of

being dissolved. Callahan (1958b) found striated muscle tissue surrounding the

corpus bursae wall of Heliothis zea (Boddie) and theorized constriction of the muscle



Terminal aperture


1 mm

Fig. 5.-Spermotophore of the lesser cornstolk borer

exerted pressure on the spermatophore corpus, thereby forcing sperm out of the struc-

ture. This may be the mode of sperm escape from lesser cornstalk borer spermato-


Primary Simplex and Spermatophore Color

Snow and Carlysle (1967) reported that the 1st secretary area of the primary

simplex in a virgin male fall army worm, Spodoptera frugiperda (J. E. Smith), is

filled with a light brown to black fluid. During mating, portions of the pigment are

passed to the female corpus bursae, while the remainder is incorporated into the

spermatophore, resulting in a darkly pigmented spermatophore. The simplex is left

transparent and colorless-to-yellow. A darkly pigmented spermatophore and a trans-

parent, colorless-to-yellow simplex together indicate a 1st mating for the male.

Subsequent spermatophores are clear to yellow.

The technique is limited by age. Newly emerged males have light to medium

brown pigment in the simplex. Males mating once and retained 4 days after removal

of females have transparent, yellow, or light brown pigment. Virgins of this age

have dark brown to black pigment in the simplex and hence are distinguishable from

mated males.

The purpose of this experiment was to determine if a color change of the primary

simplex fluid indicates a male has mated within 24 hr, and if so, how long the re-

sulting color is retained. Spermatophore color was checked to see if those passed

Ist differed from those passed subsequently.

Materials and Methods

Each of 182 3-day-old males were caged with two 3-day-old females for I

day. The females were dissected for spermatophores. Males were dissected for de-

termination of simplex color in the morning, afternoon, or evening.

The above experiment indicated virgin males tend to have translucent yellow

simplex fluid, while mated males had transparent, colorless-to-yellow fluid. To

test this further the following experiments were conducted.

Twenty-five each of 1-, 2-, and 3-day-old virgin males and 10 each of 4-,

5-, and 6-day-old virgin males were dissected for determination of simplex fluid

color and light transmission.

Thirty I-day-old virgin males were caged individually with two 1-3-day-old

virgin females for 1 day. Females were dissected for spermatophores. Ten mated

males were retained 2, 4, and 5 days after removal of females. Five males of each

group were dissected for determination of simplex fluid color and light transmission

between 9-11 AM and 5 were dissected between 9:30-11 PM.

Ten 1-day-old virgin males were individually caged with two 1-3-day-old

virgin females. Females were replaced daily by two 1- to 3-day-old virgin fe-

males for 3 days. Females were dissected for spermatophores and the color of 1st

and subsequent spermatophores was compared. Five males were dissected for de-

termination of simplex fluid color and light transmission at 11 AM and 5 at 9:30


Materials and methods for further data on simplex color and light transmission

and spermatophore color are presented in the section below dealing with mating


Results and Discussion

Table 3 indicates a progressive color change in simplex fluid color of 3-day-old

males within 24 hr after mating. All spermatophores were clear and transparent.

Simplex fluid color was translucent cream-yellow to yellow in 1- to 3-day-

old virgin males and translucent yellow in virgin 4- to 6-day-old males.

All mated males retained for 2, 4, and 5 days after removal of females had

transparent yellow simplex fluid. Six males not mating the day of caging had

translucent yellow fluid the following day.

Nine males mated on each of 3 days when caged with females 3 days. Four

males dissected in the morning had transparent colorless simplex fluid. One male

failed to mate the 3rd night and had transparent pale yellow simplex fluid. All

males dissected in the evening had transparent pale yellow simplex fluid. All

spermatophores passed on the 3 nights were clear and transparent.

The above indicates that mated males can be distinguished from virgin males

by transparent versus translucent simplex fluid for at least 5 days after mating. A

mating during the previous night is indicated by transparent colorless simplex fluid.

Color of 1st, 2nd, and 3rd spermatophores passed successively on 3 nights is iden-

tical and does not distinguish between 1st and subsequent matings.

Data from the section below dealing with mating behavior indicated the pri-

mary simplex fluid of 1-day-old males was colorless and transparent in all mated

males and translucent yellow in 2 unmated males. Apparently 1-day-old mated

males can be distinguished from unmated males of the same age within 3 hr of mating.

Egg Development and Position Relative to Age

The Lepidoptera show considerable variation in egg development at emergence.

Eidmann (1931) placed the Lepidoptera in 3 groups based on the number of full-

sized eggs in the ovaries at adult emergence: (A) species with very few full-sized

Table 3.-Color of fluid in the s t secretary area of the primary simplex of
3-day-old mated and unmated lesser cornstalk borer males at different
periods of the day following mating the previous night.

Mated Males Unmated Males
Time of Sample Color of simplex (%) Color of simplex (%)
dissection Size Clear Pale-yellow Yellow Pale-yellow Yellow

7-12 AM 51 84 16

2- 3 PM 21 57 5 38

7- 9 PM 46 33 35 8 2 22

9-11 PM 64 50 23 27

eggs at emergence, typical of butterflies and moths with a long adult life; (B)

species having a 2-or 3-fold increase in full-sized eggs in the imago, as with most

Heterocera; and (C) species with all eggs fully developed at emergence, as in the

Bombycidae and Lymantriidae.

Full-sized eggs are present in ovaries of newly emerged A. kuehniella fe-

males, but none are present in P. interpunctella females at emergence (Norris,


The purpose of this experiment was to determine the stage of egg development

and egg position in the reproductive tract of virgin females relative to age.

Materials and Methods

Moths 0-8 hr old and 1 and 2 days old were retained individually in 4-dr

vials until dissected in distilled water. Moths were classified into 4 groups; (A)

moths with full-sized eggs in the common oviduct, lateral oviducts, calyx, and

ovarioles; (B) moths with full-sized eggs in the lateral oviducts, calyx, and

ovarioles only; (C) moths with full-sized eggs in the calyx and ovarioles only;

and (D) moths with no full-sized eggs. The number of visible eggs in the ovarioles

of 0-8-hr-old females were recorded.

Results and Discussion

No full-sized eggs were present in 0-8-hr-old females (Fig. 6) which would

place the lesser cornstalk borer in Eidmann's (1931) group A. However, the moth's

life span is relatively short (8-22 days) under outside conditions (Dupree, 1965;

Leuck, 1966). An average of 26 eggs were visible per ovariole.

Unlike H. zea (Callahan, 1958b), some E. lignosellus virgin 1-day-old females

N= N= N=
100 23 56 47





o 50

o 30



0-8 hr 1 day 2 days

SGroup A. Full-sized eggs in common oviduct, lateral
oviducts, calyx, and ovarioles

V Group B. Full-sized eggs in lateral oviducts, calyx,
and ovorioles only

SGroup C. Full-sized eggs in calyx and ovorioles only

E Group D. No full-sized eggs

Fig. 6.-Egg development and position in reproductive tract of lesser cornstalk
borer virgin females relative to age

developed full-sized eggs which appeared in the common oviduct, lateral oviducts,

and/or calyx (Fig. 6).

Morphology of the Tympanic Organ

The lesser cornstalk borer has tympanic organs. Thoracic and abdominal

tympanic organs are found in 11 families of Lepidoptera within the Noctuoidea,

the Geometroidea, and the Pyraloidea. As far as known, they are lacking in all

other groups (Bourgogne, 1951). The thoracic type is confined to the Noctuoidea,

and is considered monophyletic by Kiriakoff (1963). The abdominal organs are

divided into 3 groups and appear on the 1st or 2nd segments in the Pyraloidea,

the Geometroidea, and the Drepanoidea. The abdominal types are poorly known

but appear polyphyletic in origin. Eggers (1919, 1925, 1928) and Kennel and

Eggers (1933) published extensive works on the abdominal organs, but in recent

years, these organs have been ignored (Kiriakoff, 1963).

In the Pyraloidea, tympanic organs are found in the 1st abdominal segment,

and are often obscure externally since the tympani face the thorax (Bourgogne,

1951). Tympanal cavities are shallow or essentially absent. Principal tympani

are situated ventrally on the modified anterior portion of the 1st abdominal ster-

nites (sternites 1 and 2), and ore separated by a strongly scaled and sclerified

longitudinal band. The band frequently continues posteriorly in 2 large projecting

lobes that sometimes serve as tympanal opercula. Each tympanic organ has a

tympanal sac enclosed in a chitinous hemisphere formed by integumental invagi-

nation. Its walls are formed by 2 lamellae which remain completely separated, or

may be partly or completely closed. The scolophore (=scolopophorous organ), con-

taining 4 scolopalia, may extend from the tympanum to the hemisphere surface

or to an internal ridge. In some subfamilies, as many as 5 accessory tympani may

be present: (A) a single dorsal tympanum composed of a thin metapostnotal ridge;

(B) a pair of lateral tympani on the metathoracic epimera or on either side of the

metapostnotum; and (C) a pair of coxal tympani on the posterior face of the meta-

thoracic coxae.

Materials and Methods

Five 1-day-old adults of each sex were dissected in distilled water. The

thorax was separated from the abdomen, and the 1st abdominal segment bearing

the tympanic organs was separated from the remaining abdominal segments. This

permitted an unobstructed view of the anterior surfaces. To expose internal struc-

ture, an incision was made just posterior and lateral to the anterior margin of the

right organ.

Results and Discussion

Figs. 7 and 8 illustrate the external and internal structure of the organs.

There is no sexual dimorphism in the organ structure. The tympanal cavity

is essentially absent since only narrow ridges (Fig. 7, S.r) circumscribe the

anterior surface of the 1st abdominal segment. The tympanal sacs (Fig. 8) and

tympani (Fig. 7, T) are separated by a strongly scaled and sclerified longitudinal

band (Fig. 7, S.l.b) which terminates ventral to the oriface thru which the internal

organs pass (Fig. 7, 0). The metathoracic coxae and the scales on the longi-

tudinal band obscure the tympanal surface externally. The principle tympani are

ventrally located, and the presumed scolopophorous organs, easily seen thru the

thin tympanal integument, pass ventrally from the tympanic surface to an internal


ridge (Fig. 8) which leads to the mesal surface of the tympanal sac. Two com-

pletely separate lamellae farm the tympanal sac wall. Integumentary folds possi-

bly formed from the metathoracic epimera overlap the tympanic surfaces and form

presumed accessory tympani (Fig. 7, A.t).

The tympanic organ structures of E. lignosellus agree with the general

pyraloid described above.

Explanation of Fig. 7

A. t Accessory tympanum

O Orifice for internal organs

T Tymponum

S.r Sclerotized ridge

S.o Scolophophorous organ

S.l.b Sclerotized longitudinal band


A. t

S. ..b
I" .

1 mm

Fig. 7.-External anterior view of the first abdominal segment of the lesser
cornstalk borer moth illustrating the tympanic organs on the excised


Ridge on tympanal sac wall

Tympanal sac
Scolopophorous organ

.5 mm

Fig. 8-Internal lateral view of the right tympanic organ of the
lesser cornstalk borer with the lateral wall of the tympanal
sac removed


Mating Cage Conditions

Workers used various mating cage conditions. Luginbill and Ainslie (1917) used

glass lantern chimneys of unspecified size in mating and oviposition studies with single

pairs. They stated that fed moths lived longer than starved, but did not distinguish

between the 2 groups in their data. Dupree (1965) mated pairs of moths in 30 x 100

mm shell vials with about 30.0 cc/moth, and fed them honey diluted with 1 port

water adding sodium benzoate to prevent spoilage. Leuck (1966) retained an un-

specified number of moths in a 1 cu ft polyethylene covered mating cage, and fed

them 10% honey-water. Calvo (1966) retained 35 moths of each sex in a screen cage

with 113.8 cc/moth. No mating occurred unless there were 5 moths of each sex per

cu ft. Stone (1968) used 10 moths of each sex per mating-oviposition cage with 30.3

cc/moth. Both Calvo and Stone fed moths 2% sucrose solution.

The purpose of this experiment was to find a convenient cage size with accept-

able top material and cage placement for mating behavior studies, and to determine

if fed and unfed moths mated with equal frequency.

Materials and Methods

Vials of 4- and 40-dr were tested as mating cages. In each of ten 4-dr vials,

1 pair of 1-day-old (0-24 hr) moths and a cotton wad were placed. The cotton wads


were left dry in 5 vials and saturated with 2% sucrose solution in 5 vials. Satu-

rated cotton wads were resaturated when nearly dry. All vials were stoppered

with cotton plugs, placed horizontally, and held for 6 days. Further tests with

fed moths in 4-dr vials involved 6 pairs of 1-day-old moths for 5 days, 4 pairs of

2-day-old moths for 7 days, and 4 pairs of 3-day-old moths for 7 days.

In the 40-dr vials, mating frequency of fed versus unfed moths was com-

pared. In addition, screen versus cellucotton tops and vertical versus horizontal

vial placement were tested concurrently using a series of 176 vials. The influ-

ence of water versus the 2% sucrose solution on mating frequency was not tested.

In each of the 176 vials, 1 pair of 2-day-old moths was held 4 days. In 88 of

these vials, the cotton wad was saturated with 2% sucrose solution, in the other

88 vials they were left dry. Forty-four of each set of 88 were closed with squares

of 14 x 18 mesh/in fiberglas screen held in place with rubber bonds, while the

other 44 were closed with squares of cellucotton 1/2 mm thick held in place with

rubber bands. Lastly, each set of 44 vials was again divided with 22 held verti-

cally and 22 held horizontally.

At the end of each test, females were dissected for spermatophores.

Results and Discussion

No mating occurred in 4-dr vials, where available space was 7.2 cc/moth.

Under fed versus unfed conditions, 1 fed female, 3 unfed males, and 1 unfed

female died.

Mating occurred in the 40-dr vials, where available space was 29.5 cc/moth

(Table 4). Chi square analysis of the multiple factor test indicated no significant

difference at the 1% level among position, cage top material, and fed versus

Table 4.-Cage conditions and spermatophores passed by 2-day-old fed and unfed
lesser cornstalk borer adults, tested for 4 days in 40-dr vials, 1 pair per vial, 22
replicates per test.

Conditions dead

Screen top, 0


Screen top, Ima(2)b


Cellu. top, 0


Cellu. top, 0


Cages Cages Multiple Total
without with 1 or matings sprmts.
mating more sprmts. sprmts. cages passed

Fed (2% sucrose)

10 12 2 2 20

4 2

10 12 2 5 19

3 1

6 16 2 4 27

3 2

4 1

8 14 2 5 22

4 1

Unfed (No sucrose)

Screen top, 8 a 12

vertical 19(0)b

Screen top, 10 ad 10


Cellu. top, 6 ad 6


Cellu. top, 5 dd 12


mates attached when cage dismantled
number of spermatophores accepted


2 2 12

12 0

16 0

10 2 1 11

unfed moths for a single mating per pair. Fed moths had highly significantly more

multiple matings than unfed moths. Twenty-nine unfed males died while no fed

males died during the tests.

Forty-dr vials were thus considered adequate for mating studies. Moths should

be given sugar solution to avoid death within 4 days if the moths are retained for

several days, or if multiple matings are desirable.

Mating Behavior

The mating behavior of the lesser cornstalk borer has not been reported in the

literature. Luginbill and Ainslie (1917) assumed mating occurred the 2nd night

after emergence. Leuck (1966) stated that moths were most active in the field

after dark in still air with low humidity at temperatures exceeding 800 F. He felt

these conditions were optimum for mating and oviposition.

A. kuehniella and P. interpunctella females "call" prior to mating, that is,

the abdomen is bent dorsally between the wings and the ovipositor is alternately

protruded and retracted. Calling by P. interpunctella females is not correlated

with egg development since it occurs before and after fu I I- sized eggs are pre-

sent, and after all eggs are laid (Norris, 1932).

Richards and Thomson (1932) reported mating behavior in a general discussion

of the genera Ephestia, Anagasta, and Plodia, but made no reference to behavior

of a given species. Receptive females begin calling with the apical half of the

abdomen bent dorsally between the wings. The ovipositor is alternately protruded

and retracted. A male begins fluttering around the female which does not respond

or runs away. Eventually the female stops, the male faces her head to head and

bends his abdomen dorsally and anteriorly to grip the female abdomen tip. Quickly

the pair twists around and assumes an end to end copulatory position.

Williams (1938) stated that the A. kuehniella female calls with the wings

spread and the abdomen curved upward until mating occurs. Females are quiet

(=stationary?) when calling. The male moves about vibrating his wings until he

meets a female. He then curls his abdomen towards her and couples.

Schwink (1953) reported that A. kuehniella and P. interpunctella males re-

spond to their respective females with long-lasting whirrings. Whirs lasting 40

sec to several minutes are separated by short pauses and occur many times within

several hours.

Brindley (1930) stated that copulation of A. kuehniella occurs after midnight

the day of emergence, and lasts 4-6 hr. Norris (1932) reported that copulatory

duration of A. kuehniella is 3-4 hr, and 1-1 1/2 hr for P. interpunctella. Williams

(1938) reported that copulation lasts 3-5 hr for A. kuehniella.

The purpose of this experiment was to observe pair formation and courtship of

E. lignosellus, time of coupling, duration of copulation, uncoupling of mates, and

post copulatory activity. In addition the following factors were observed: number

of spermatophores passed per mating; and egg development and placement of full-

sized eggs in the reproductive tract of mated and unmated females.

Materials and Methods

Pairs of 1-day-old moths were placed in each of 5 clear plastic containers,

12 1/4 cm x 17 1/4 cm x 6 cm deep. Cellucotton squares, 3 mm thick and 4 cm

on a side, were folded in 3rds, saturated with 2% sucrose solution, and placed in

the left back corner of the cage floors. The cage mouths were covered with 2-mm-

thick cellucotton held to the uppermost cage perimeters with rubber bands to permit

maximum visibility. Cages were set on platforms composed of 2 containers, iden-

tical to the cage, stacked on top of each other and separated from other platforms

by 28 cm. One ft behind each cage was a 7 1/2 watt red light with a reflector

which illuminated the cages at about 1 ft-candle. The main lights were turned out

and the red lights turned on at 8:00 PM.

The laboratory temperature during experimentation was 45.5 4- 30 C both

nights. The 1st night, the relative humidity control was turned to capacity at

8:00 PM and turned off at midnight. Before the experiment, humidity was 46%

RH, at midnight 70 4 4%, and at 8:00 AM 46 4- 5% RH. The 2nd night, humidity

was 46 + 5% RH.

Five pairs of moths were observed each of 2 nights, from 8:00 PM to 11:00

PM at 15 min intervals, and continuously from 11:00 PM to 6:40 AM the 1st night,

and from 11:00 PM to 5:20 AM the 2nd night. Thereafter, observations were made

every 5-40 min until 8:06 AM the 1st night and 6:45 AM the 2nd night. During

breaks between the final observations, females were dissected for spermatophores

and for observations of egg development and placement in the reproductive system.

Males were dissected and the color of the 1st secretary area of the primary simplex

recorded; these results are reported in the section above dealing with primary sim-

plex and spermatophore color.

Results and Discussion

Until midnight the moths remained still or ran and/or flew about the cage with

no seeming orientation to each other. If a pair met, they avoided each other by

turning aside or dropping to the cage floor. Females were generally more active

than males up to midnight, in contrast to daylight hours when the reverse is true,

as seen in mating-oviposition cages in the culture room and in handling moths in

other experiments.

In the description below, "calling" by females refers to a posture in which the

abdominal tip is thrust between and above the wings, and the ovipositor is inter-

mittently protruded and retracted. "Whirring" by males refers to the wings raised

vertically over the thoracic dorsum, and forming a blur describing arcs of an esti-

mated 300. At the same time, the abdomen is raised dorsally with the tip between

the wings, except immediately before attempted coupling.

The female initiates pair formation by calling as she remains stationary on the

horizontal lower surface of the cellucotton cage top or on the vertical cage side.

The male begins vibrating his antennae up and down asynchronously, makes a circle

in place, and approaches the female with his wings slightly parted. If the male

approaches the female from behind, he flails her abdomen tip with his antennae,

the female makes a half circle in place, and the moths flail each others' antennae

head to head. If on the other hand the male approaches the female head to head,

the moths flail each others' antennae. The male then whirs his wings. The female

may make no, or several circles in place. The moths continue flailing each

others' antennae if the female does not circle, or the male flails her body with his

antennae if she circles. During this time the male continues bursts of whirring,

separated by brief pauses. With the female facing the male, the male continuously

whirs his wings as he curls his raised abdomen with claspers extended towards the

female, quickly twists toward her right or left, and strikes at her abdomen tip. If

coupling is successful, the male stops whirring and pivots in a half circle as the

female pivots slightly placing the body axes in a straight line, end to end, flat to

the surface. If the pair fails to couple, the female continues calling while the

male pauses, the moths flail each others' antennae, and the male whirs continuous-

ly as he strikes again. This procedure is repeated 3-5 times until coupling occurs

or the female walks away. After coupling and pivoting to the end-to-end position,

the pair remains stationary and oppressed to the surface.

Uncoupling begins with the mates gradually raising the abdomens to form a

130-1400 angle to each other. The male pumps his abdomen, finally raises his

wings several times, and sometimes vibrates them briefly. The female may pump

her abdomen as she grasps the surface. The pair may turn a half circle and back

again while pulling alternately, or the male may turn about 400 and then back

again. The male abdomen may be bent into a vertical "S" shape during this process

or remain straight but raised vertically. The mates ultimately uncouple either from

a straight line position or at a 1400 angle to each other laterally.

After uncoupling, the mates tend to be active for 5-10 min moving about the

cage and feeding, but finally settle down for the rest of the night.

Eight of the 10 pairs mated. Calling occurred from 1:15 AM to 6:40 AM the

1st night, and from 1:45 AM until continuous observation was terminated (6:45 AM)

the 2nd night. Of 73 callings recorded, 19 initiated courtship, i.e., the attracted

males whirred at least once next to the females. Of the 19 courtships, 7 led to

coupling. In addition, 12 courtships occurred with females not observed calling

immediately prior to courtship. However, half of these were in a single cage that

was not observed as closely as the other cages, and calling could have occurred.

In addition, courtship was sometimes initiated within minutes after calling began,

and could easily be missed. Accepting these possibilities, apparently only calling

females attract males.

In 4 matings, females called only once during the night, from 1/2 to 5 min,

and were coupled within 1-7 min after initiating calling. Two other females

called intermittently over periods of 100 and 47 min in intervals lasting 2-54 min

and 2-8 min, respectively, before coupling. The 1st was courted only once while

the 2nd was courted 4 times, once before she was observed calling during the

night, and 3 times when she called.

The pair formation and courtship behavior of E. lignosellus include activities

suggestive of olfactory stimuli. Norris (1933) stated calling P. interpunctella fe-

males stretch the intersegmental membrane bearing secretary tissue near the ductus

bursae orifice. P. interpunctella males become highly excited in the presence of

calling females, but never become sexually excited in the presence of non-calling

females (Norris, 1933; Barth, 1937). Dickens (1936) described scent scales aris-

ing from glandular areas on the 8th abdominal segment of A. kuehniella, E. cautella,

E. elutella, and P. interpunctella. Females of all 4 species had glandular inter-

segmental folds between the 8th and 9th segments. E. cautella females also have

2 internal odoriferous glands which open into the oviduct near the genital pore.

G'tz (1951) stated female calling in Lepidoptera exposes glands secreting sex phero-

mones. Evidence does not contradict that E. lignosellus males court and couple

with females that are calling. Barth (1937) stated glands of E. elutella males se-

crete an odorous substance that increases female excitement in copulation. Vibra-

tion of the wings disperses the odor. Courting E. lignosellus males whir with the

abdomen tip, with claspers extended, held between the wings.

Coupling of E. lignosellus occurred from 1:40 AM to 6:40 AM with 7 of the 8


couplings occurring by 4:40 AM. Average time in copulo was 102 min (range 81-

134) including 5-10 min for uncoupling.

In unmated females, the membranous portions of the corpus bursae wall were

pressed together and no visible fluid was present within the bursae. All mated

females had a greenish fluid in the corpus bursae anterior to the spermatophore.

Not more than 1 spermatophore was passed per mating.

Among mated females, 3 had full-sized eggs in the common and lateral ovi-

ducts, 4 had full-sized eggs in the lateral oviducts but not in the common oviduct,

and 1 had only immature eggs, located in the ovarioles. The 2 unmated females

had full-sized eggs in the lateral oviducts but not in the common oviduct. It

appears E. lignosellus females, like P. interpunctella (Norris, 1932) mate without

regard to egg development.

Influence of Additional Females on Male Mating Frequency

The presence of receptive moths was an important factor in mating studies.

Mating cage sizes used by Luginbill and Ainslie (1917), Dupree (1965), Leuck

(1966), Calvo (1966) and Stone were summarized in the preceding experiment.

Mating occurred in all cages except 4-dr vials used by Stone. Pairs of moths

mated in 40-dr vials, but to assure that receptive females were present for test

males in other experiments, I decided that greater female numbers per cage

might be desirable. The purpose of this experiment was to determine if additional

females per male influenced mating frequency.

Materials and Methods

Two-day-old males and females were caged in 40-dr vials for 1 day using

the following numbers of individuals, male:females, with the space available per

moth in each case: 1:1, 73.5 cc; 1:2, 49.0 cc; 1:3, 36.8 cc; 1:4, 25.4 cc. Equal

numbers of each ratio were run on a given day until the ratios were replicated 100

times. At the end of each test, females were dissected for spermatophores.

Results and Discussion

Males mated with approximately equal frequency at all 4 ratios: 1:1, 60%;

1:2, 61%, 1:3, 75%; 1:4, 70%. Chi square analysis indicated no significant

differences at the 5% level. Either the lack of successful mating is principally

attributable to the male or else additional females resulted in inhibiting factors

approximately equal to the increased probability that at least 1 female would be

receptive. Not more than 1 spermatophore was passed per night per male.

Influence of Age on Mating

There is much variation in the Lepidoptera as to age of mating. Richards

and Thomson (1932) found that moths of the genera Ephestia and Plodia adults are

ready to mate soon after emergence, almost as soon as the wings are dry. The

corn earworm, H. zea, never copulates the 1st night after emergence or on fhe

emergence night, and all copulations occur between the 2nd and 7th complete

nights after emergence (Callahan, 1958a). The cabbage looper, Trichoplusia ni

(HUbner), most frequently mates the 2nd and 3rd nights after emergence. Males

never mate on the Ist night after emergence, but a small percentage (7%) of fe-

males mated the 1st night (Shorey, 1964). However, Henneberry and Kishaba

(1967) reported male cabbage loopers mated infrequently the 1st night after emer-

gence and most frequently the 3rd and 4th nights after emergence. The pink

bollworm, Pectinophora gossyplella (Saunders), mates most frequently at ages 5-6

days (Ouye et al., 1964). The oriental fruit moth, Grapholitha molesta (Busck),

mates within 24 hr of emergence, and males mate daily during the 1st 7 days after

emergence (Dustan, 1964). The granulate cutworm moth female, Feltia subterranean

(F.), mates most frequently the 3rd night after eclosion (Cline, 1967).

The purpose of this experiment was to determine the influence of age on mat-

ing of 1-6-day-old lesser cornstalk borer males and females.

Materials and Methods

Moths 1-6 days old were tested at 1 male:4 females and vice versa for 1

day. All combinations of ages and both sex ratios were replicated 5 times each,

making a total of 360 test cages. At the end of each test, females were dissected

for spermatophores.

Results and Discussion

The data were pooled as indicated in Fig. 9. The overall average for the

experiment was computed since mating frequency under the 4 conditions plotted in

Fig. 9 was essentially the same (average 61%, range 60-62%). Mating frequency

of each age group was compared with the overall average using a 2-tailed "t" test.

None of the 24 mating frequencies were significantly different from the over-

all average at the 1% level. Thus the lesser cornstalk borer mates equally well at

age 1-6 days under the above conditions.

Influence of Male Antennectomy on Mating

Dethier (1953), Schneider (1964), and Jacobson (1965) include many re-

ferences establishing the antennae of insects as the principal site of olfactory

123456 1234 5
Days age males Days age males
Id: 499 4d.d: 19

Male age held constant while female age
ranged from 1-6 days.

123456 123456
Days age females Days age females
4de: 19 1 d: 499

Female age held constant while male age
ranged from 1-6 days.

Fig. 9.-Percent mating of 1-6-day-old lesser cornstalk borer adults caged for 1 day


receptors. This may explain why male moths deprived of their antennae or having

antennae coated with various substances either do not mate or mate infrequently.

The purpose of this experiment was to determine the influence of bilateral

antennectomy of the male on mating.

Materials and Methods

Two 2-day-old females were caged with two 2-day-old males handled in 1

of 3 ways. Group A males were caged untreated. Group B males were knocked

down by a 5 sec exposure to CO2 and the left meso- and right metathorocic legs

were excised between the thorax and the coxae. Group C males were also knock-

ed down with CO2 as in Group B and both antennae were excised between the

head and the scape. All excisions were done with the aid of a microscope.

Groups were run concurrently and replicated 25 times. Cages were retained

2 days.

Results and Discussion

In Group A, 47 spermatophores were passed, in Group B, 43, and in Group

C, 1.

Complete bilateral antennectomy inhibits mating of E. lignosellus males.

Based on behavior of other Lepidoptera, this is possibly due to removal of olfactory

receptors which trigger pair formation, courtship, and mating on reception of the

female sex attractant.

Longevity of Virgin and Mated Moths, Spermatophore Passage and Acceptance,
and Fecundity

The purpose of this research was to determine the longevity of virgin and

mated moths, male and female mating frequency, the number of eggs laid per

mated female, and the temporal oviposition pattern during the total oviposition

period of mated females.

Materials and Methods

Twenty-five each virgin males and females were retained for life. Newly

emerged moths were placed singly in 40-dr vials and assigned an identification

number. Four to 8 moths of the same sex were caged as available on a given date.

Males were caged on 5 days, every 3rd day, and females were caged on 4 days,

2, 6, and 5 days apart.

Newly emerged moths used concurrently for longevity, mating frequency,

and fecundity records were placed in 40-dr vials and assigned an identification

number. Three 1- to 3-day-old virgin moths of the opposite sex were placed in

each vial and were replaced daily for the life of the retained moths. As the re-

tained moths died, they were replaced until 25 of each sex were tested. Dead

retained mated females were dissected for spermatophores and retained eggs. A

moth was considered dead when it failed to move appendages or pump the abdomen

when gently probed. Females caged with single retained males were dissected for

spermatophores when replaced by virgin females.

The research was conducted from January to March, 1967. On 10 February,

cotton wads were replaced by cellucotton wads in the 40-dr vials, since older

moths tended to entangle themselves in the cotton fibers. To statistically examine

the influence of this change, using analysis of variance, all retained mated moths

dying prior to the change and exposed to no more than 6 days to cellucotton wads

were assigned to group 1. Males with identification numbers 1-14 (excluding male

no. 11 which was exposed to cellucotton wads for 11 days) and females no. 1-6


(excluding female no. 4 which was exposed to cotton wads for 7 days) were in group

I. All other moths were in group 2 except male no. 11 and female no. 4.

Since nearly all virgin moths survived beyond 10 February, moths were assign-

ed to groups based on the dates they were initiated in the experiment. Longevity,

spermatophores passed or accepted, total, viable, and sterile eggs laid, number of

eggs retained at death, length of oviposition period, and longevity alone were

checked statistically using correlation coefficients for mated and virgin moths,


Eggs laid by retained mated females on the cellucotton tops, vial sides and

bottoms, were set aside for 24 hr before counting fertile and sterile eggs. Fertile

eggs turn from cream white to red, while sterile eggs remain cream colored or turn

red at one end only.

Results and Discussion

Differences in longevity and fecundity when compared with other workers

(Tables 5 and 7) may result from rearing history, summarized under rearing proce-

dures above, methods of handling adults, and genetic differences. Luginbill and

Ains!ie (1917), Dupree (1965), and Leuck (1966) retained adults in unregulated

rooms or outdoor screened insectaries, while Calvo (1966) maintained adults at

constant temperatures and humidities. Sanchez (1960) worked with laboratory in-

sects at unspecified conditions, except for a few observations discussed below.

King et al. (1961) did not indicate what conditions were involved with his data.

At the time of experimentation, my colony had passed thru 7 generations. Thus

the genetic pool may have changed from that of the original stock that Calvo (1966)

used and influenced the results.

Table 5.-Longevity of lesser cornstalk borer adults.

and State

Stone. Fla.






Luginbill & 6 7

Ainslie. 1917.

Fla. &S.C. 9 7

Sanchez. 1960. 6 12

Texas 9 7

King et al. 6 & 9 ?

1961. Texas

Dupree. 1965. md 17c(1957)

Ga. md (1958)

mS 17c(1957)

m9 (1958)

Leuck. 1966. v 6 ?

Ga. m 9 ?

v ?


2% sucrose

some fed sugar


Days life
Mean4SE Range Median

24.2+1.5 13-46 24

42.441.7 25-64 42

18.1-1.7 12-31 17

37.6-1.8 22-55 35

12.140.5 7-18 10



7. 10.5


dilute honey & 11.4

sodium benzoate 17.9



10% honey 22.241.3





: Dupree used at least 17 pairs in 1957-1958 combined.

Longevity of individual moted males and females are shown in Figs. 10 and 11,

respectively. Males exposed to cotton wads lived an average of 4.0 days shorter

and females lived 2.5 days shorter than moths exposed to cellucotton wads. How-

ever, these differences were not statistically significant.

Mated males lived an average of 12.7 days (range 5-28) after passing the last

spermatophore (Fig. 10). Males no. 17 and 20 are not included in the average

since male no. 17 may have died prematurely in copulo and male no. 20 failed to

pass a spermatophore. Mated females lived an average of 4.7 days (range 1-13,

median 4) after the last oviposition day. Virgin females lived roughly twice as

long as mated females, thus agreeing with Leuck's data (1966) (Table 5).

Callahan (1958a) concluded that once a corn earworm moth mates, it be-

comes less active than a virgin moth and hence lives longer on the average than a

virgin. However, virgins held in holders for life lived longer than mated moths.

He acknowledged his conclusion did not seem to hold for E. kuehniella (Zeller).

The adults do not ordinarily feed and virgins possibly live longer by absorbing

retained eggs.

Norris (1933) indicated that unfed virgin E. kuenniella females lived as long

as mated females fed sugar solution. Perhaps virgin females might live longer than

mated females if fed, as was the case for E. lignosellus. Feeding versus starvation

is probably the decisive factor in E. lignosellus longevity, not degrees of activity

at least in males, as seen in 29 deaths of mated unfed males in the mating cage

conditions experiment versus no deaths of mated fed males.

Spermatophore passage and acceptance results are shown and compared with

other species in Table 6. Figures 10 and 11 show spermatophore passage patterns.

Table 6.-Spermatophore passage and acceptance during the lifetime of
various Lepidoptera


Shorey et al.


Shorey. 1964.

Dustan. 1964.

Ouye et al.


Cline. 1967.

Henneberry &

Kishaba. 1967.c

Hughes. 1967.









per mating
Range dd : 99

0-6 ?

0-10 1:2

1-4 20:20 &


0-10 1:3a

0-8 6:1ab

0-8 1:3

Scientific and
common name

Trichoplusia ni

Cabbage looper

Grapholitha molesta

Oriental fruit moth

Pectinophora gossypiella

Pink boolworm

Feltia subterranean

Granulate cutworm moth

Trichoplusia ni

Phthorimaea operculella

Potato tuber moth

Elasmopalpus lignosellus

Lesser cornstalk borer





a Three virgin moths age 2-5 days, and virgins no more than 2 days old replacing
dead moths, were added every 3-4 days for life of test moths.

b When 75:25 d:99 were caged, comparable results were obtained.

c The authors were checking temperature effects concurrently.

9 1.2-1.4 ? 3:3



'2' '4' '6' '8' '10 '12' '14' '16' '18' '20' 22' 24' 26' '28' '30
Days ife

'32' 34 36 38' '40 46

Fig. 10.-Mated lesser cornstalk borer male longevity and spermatophores passed

a Died in copulo

N k\\l\\\ \\


S'^N,.I ,, NN,,


n 20
.2 14
8 12


"- 25

S293 (38) 1
3 4 385 (9) 2
1\\\\\\\\\\\\' 422(7) 2
\\\\\\\ 370 (0) 2
<\\\\\\\\\\\\ 4 458 (135) 3
J\ \\483 428 (10) 3
\\\\\\\ \ 356 (14) 1
\\\\\\\\\\\\\ 40 (4) 1
\\\\\\\ \514 (9) 2
373 (114) 2
\\\\\\ \\ 385 (4) 2
419 (3) 2
483 (79) 1
J\\\\\\\\\ ~ 465 (16) 1
~~- I\\\\\\\\ \ 459(0) 1
~- k\ \ l\ J,\NJ 413 (3) 2

508 (9) 1
514(17) 3
562 (2) 2
318(6) 1
396 (29) 1
490 (7) 2
428 (3) 1
294 (34) 1

354 (24) 2

'2' '4 6' 8 '10' '12' '14' '16' 18' '20' 22' 24' 26' 28' '30' '32' '34' 136'
Days Life

Fig. 11.-Mated lesser cornstalk borer females longevity, oviposition period, fecundity, and spermatophores accepted

a Total eggs laid (sterile eggs) number spermatophores accepted.
bDied in copul
Died in copulo.









I\\\~\\\\\\\\\\\~\\\\`I ~

`````` ````` `` \` `


" ` ` ` ` ` ` ` ` ` ~~` ` '''

35A 124) 7

Figure 12 indicates the total number of spermatophores passed by 25 males per day.

Mated males dying prior to replacement of cotton wads with cellucotton wads

passed an average of 3 spermatophores fewer than males after replacement, but the

difference was not statistically significant.

No more than 1 spermatophore was passed per day per male except for male no.

16 which passed I spermatophore to each of 2 females the 1st day of caging.

Authors included in Table 6 used various methods to determine spermatophore

passage and acceptance during moth life span. Shorey (1964), Cline (1967),

Hughes (1967), and Stone replaced virgins of the opposite sex daily for life of test

moths. Shorey et al. (1962), Dustan (1964), and Henneberry and Kishoba (1967)

caged moths at various ratios for life of females with no daily replacement of virgin

males. Ouye et al. (1965) initiated studies with 3 virgin females per male and

6 virgin males per female to determine potential mating frequency of males and fe-

males caged for life. Three more virgins were added every 3-4 days during the

test moths' lives, and dead moths were replaced by virgins to assure receptive maths

of the opposite sex were present.

The average reproductive life of E. lignosellus males, counting from day 1 to

the day the last spermatophore was passed (male no. 20 was not included since it

passed no spermalophore) was 10.2 days (range 3-18, median 11) (Fig. 10). Within

3 days, all males except male no. 20 had mated at least once. In 5 days 49% of

all spermatcphores were passed, in 14 days 99% (Fig. 12).

The lesser cornstalk borer showed no significant correlation between male mating

frequency (spermataphores passed) and longevity. In contrast, Shorey (1964) reported

the principal factor limiting copulation frequency of T. ni males was longevity.





5 16

- 14

'C 10


2 -b e

....L,. I I I I
0 2 4 6 8 10 12 14 16 18 20

Days Paired

Fig. 12.-Total number of spermatophores passed per day by 25
lesser cornstalk borer males, number of males after
day 13 as indicated

a 24 live males in sample
b 23
c 22
d 21
e 20


Shorey (1964) speculated the female may be the limiting partner, determining

the average mating frequency in a population having an equal sex ratio. The

lesser cornstalk borer female is the limiting partner, since males passed an average

of 7.2 -- 0.8 spermatophores during a lifetime when caged daily with 3 virgin fe-

males, while females accepted only 1.7 -- 0.2 spermatophore under comparable


Male no. 17 and female no. 8 remained continuously coupled to mates for 3

nights and 2 days before dying. In contrast, male no. 25 coupled on day 5 and

remained coupled with 1 female until day 6, when it uncoupled and mated with

another female. On day 7, it coupled again with 1 female thru day 8 when it un-

coupled. The observations indicated an E. lignosellus male can disengage after

prolonged coupling. Shorey (1964) and Callahan and Chapin (1960) reported that

T. ni and H. zea remaining coupled during the day were unable to disengage and

died coupled. Hughes (1967) mentioned mating pairs of P. operculella unable to

separate. Luginbill and Ainslie (1917) reported a caged pair of lesser cornstalk

borer maths found in copulo unable to uncouple.

Dissections of prolonged coupled moths, in this experiment and in mating-

oviposition cages used in colony maintanence, showed the cornutus, the chitinous

tooth on the everted endophalus, was inserted into the bursa copulatrix and bent

at a right angle to the endophalus where it entered the bursa, thus preventing re-

traction of the endophalus thru the ductus copulatrix. In some cases, a malformed

spermatophore collum and corpus entangled the endophalus and cornutus within the

bursa and ductus copulatrix.

Table 7 compares fecundity results with those of other workers. Fig. 13

Table 7.-Fecundity of the lesser cornstalk borer

References Sample Eggs laid/female
and states size (99) Mean 4- SE Range

Stone. Fla. 25 419.54 14.7 293-562

Luginbill & Ainslie. 6 192 91-342

1917. Fla. & S.C.

King et al. 1961. 124


Dupree. 1965. 17a(1957) 128.9 11-261

Ga. 170(1958) 61 5-221

Leuck. 1966. ? 125.7 20.5 2-314


Calvo. 1966. 35 67


SDupree used 17 i9 in 1957-1958 combined.


illustrates the average number and standard error of eggs laid per day. No signifi-

cant correlations were found among longevity, spermatophores accepted, total eggs

laid, sterile eggs laid, and length of oviposition period. Correlation between

number of eggs laid and the number of fertile eggs was significant at the 1% level


Callahan (1958a) and Shorey (1963) found no correlation between longevity

and total eggs laid for H. zea and T. ni. Shorey (1963) also found egg production

increased as numbers of spermatophores increased for females laying viable eggs,

but percent viability was not markedly correlated with mating frequency.

In the discussion below, day refers to time of pairing, but oviposition day

refers to a day counting from the 1st day eggs were laid by a particular female or

by females. Once eggs are laid, even days without additional egg laying are

counted as "oviposition days" within the oviposition period. This happened only

4 times (Fig. 11).

Of the eggs laid by 25 females, 56% were laid by the 4th oviposition day,

or 48% by the 4th day.

The average oviposition period for 25 females, counting from the 1st through

the last oviposition day was 11.8 oviposition days (range 7-19, median 10) or

14.6 days (range 8-23, median 12) counting from the 1st day of caging through

the last oviposition day. Females delaying oviposition no more than 1 day aver-

aged 11.5 oviposition days (range 7-19), while 5 females delaying oviposition more

than 1 day averaged 13.0 oviposition days (range 10-17). Dupree (1965) found

that the oviposition period was 7.8 days (range 1-18) 1 year and 4.1 days

(range 1-9) the following year. Luginbill and Ainslie (1917) recorded 5 females

S50I I

6 40



10 ab d

2 4 6 8 10 12 14 16 18 20

Oviposition Days

Fig. 13.-Average numbers of eggs laid per day by 25 lesser cornstalk borer
females, number of females after day 12 as indicated. Standard
errors shown with horizontal lines
0 22 live females in sample
b 18
c 17
d 13
e 12
f 9

oviposited an average of 10.4 oviposition days (range 7-14).

Leuck (1966) staled that caged females oviposited nightly all their lives, but

females in the work reported here lived an average of 4.7 days (range 1-13, median

4) after the last oviposition day. Dupree (1965) stated oviposition usually occurred

on alternating days, rarely on consecutive days. Only female no. 2 laid larger

egg numbers every other day thru day 9, with differences of 50-70 eggs on suc-

cessive days. Perhaps Dupree's moths reflected temperature effects in the outdoor

insectary, as he mentioned the average minimum and maximum temperatures during

experimentation were 66.6 and 86.40 F in 1957 and 66.8 and 88.20 F in 1958.

Luginbill and Ainslie (1917) stated oviposition did not occur when the temperature

"fell much blow 800 F," but did not state clearly under what condition moths were

kept. Sanchez (1960) stated field collected adults maintained at 650 F continued

ovipositing, but adults kept at 350 F were inactive. However, he did not study

oviposition patterns. Perhaps these discrepancies in responses to temperature re-

flect differing genetic strains.

The variation in numbers of eggs laid on oviposition day 1 (range 2-135,

median 86) might result from varying times of meting an4/or varying rates of sperm

passage from the bursa copulatrix to the receptaculum seminis.

Table 3 summarizes variations from basic oviposition patterns, and includes

only females showing at least 2 of the variations Isted. All females laying more

than the average percent sterile eggs of total eggs laid are included (population

average 5.5%, lange 0-30.4%). Four of 5 females delaying oviposition more than

1 day, 5 of 8 females retaining more than 10 eggs (population average 8.7, range

1-26), and 3 of 7 females ovipositing in daily numbers differing from the usual

Table 8.-Lesser cornstalk borer females showing 2 or more variations from basic
population oviposition patterns.

Female Ave. % Delayed ovipo- Retained 10 Irregular daily
no. sterile eggs sition (days) eggs at death oviposition pattern

14 30% +

22 29% 15 a

21 16% 5

19 13% 11

4 12% 5 26 4-

11 8% 3 19 +

13 7% 7 21

a Laid 2 fertile eggs on day 1.

daily decreasing pattern (Fig. 13) are included. Only females no. 21 and 22 laid

more than the average total number of eggs. Females no. 4 and 19 represent the

2 lowest fecundity records obtained.

The data indicate females laying more than the average percent sterile eggs

of all eggs laid tend to show other variations. Seven females not included in Table

8 showed only 1 variation of the 4 listed.

Nineteen females began ovipositing on day 2. Female no. 22 laid eggs the

1st day of caging, while 5 females delayed oviposition more than 1 day (Fig. 11).

A. kuehniella females underwent periods of quiescence after mating, usually 12 to

24 hr. During this time the sperm passed from the bursa copulatrix to the recepta-

culum seminis. Then oviposition began, lasting to within the last day or 2 of life

(Norris, 1933). If this is the case in E. lignosellus, then one could assume the

19 females probably mated on day 1 and were ready to oviposit on day 2. Female

no. 22 must have mated on day 1, as the 2 eggs laid were fertile. The 5 females

delaying oviposition may have mated the day before they initiated oviposition or

perhaps they indicated a wide range of sperm passage rate from the bursa to the

glandula receptaculum.

Thirteen females laid decreasing numbers of eggs from oviposition day 1, dis-

regarding increases of less than 10 eggs in production on 2 successive days. If

oviposition day 1 is disregarded due to the variation in egg numbers laid, then 18

females laid decreasing numbers of eggs daily. Norris (1933) found A. kuehniella

females laid the greatest number of eggs during the 1st 2 days and then decreased

production gradually until the last day or 2 of life, when 1, 2, or no eggs were

laid. This agrees with lesser cornstalk borer egg production, except that E.

lignosellus females live longer on the average after the last oviposition day.

Of females differing from the daily decreasing oviposition pattern, 1 tended

to oviposit on alternate days (female no. 2 discussed above), 1 reached peak

production on oviposition day 3, and another on oviposition day 4. Four females

reached a 2nd peak production (at least 15 more eggs laid' than on the previous

oviposition day) after the 1st 2 oviposition days -- 2 on oviposition day 4, 1 on

5, and 1 on 6.

A. kuehniella females laid sterile eggs at any point in life (Norris, 1933).

All gradations in fertilization reduction occurred and oviposition of no viable eggs

was associated with the absence of sperm from the receptaculum seminis of mated

females or with the presence of small quantities of sperm, much smaller than in

normally mated females. When spermatozoa were present, they were less violent-

ly motile than usual, and in some cases they were motionless, perhaps due to re-

tarded spermatogenesis, which also might cause the male to pass reduced quantities

of sperm. Altho the above factors were not checked in my research, they might

have influenced sterile egg production.

Twenty-two females laid less than 10% sterile eggs of all eggs laid on ovi-

position day 1. The 3 females laying more than 10% laid 20, 49, and 66%. Two

females laid sterile eggs every oviposition day (females no. 21 and 22), while 2

females laid no sterile eggs during the entire oviposition period (females no. 6

and 23).

Concerning spermatophores accepted by females listed in Table 8, 4 females

delaying oviposition accepted 1 spermatophore each. A 5th moth delaying ovi-

position accepted 2 and oviposited in a daily pattern of decreasing numbers of

eggs as shown in Fig. 13. Assuming no parthenogenesis occurred, all 5 females

mated on or by oviposition day 1, since each laid some fertile eggs on oviposition

day 1. The other 3 females in Table 8 accepted 1, 2, and 3 spermatophores (fe-

males no. 19, 14, and 22, respectively). Females no. 4, 11, 19, and 21 tended

to lay increasing percentages of sterile eggs daily as fewer eggs were laid. Per-

haps the sperm supply was becoming exhausted with time.

The 3 of 25 females accepting 3 spermatophores retained 14-19 eggs at death.

Five other females (Table 8) (4 accepted 1 spermatophore, 1 accepted 2) retained

more than 10 eggs at death. Correlation between the number of spermatophores

accepted and the number of eggs retained at death was significant at the 5% but

not at the 1% level (r=.5006).

Of females ovipositing daily eggs numbers varying from the basic curve

(Fig. 13), 3 females accepted 1 spermatophore and 4 females accepted 2.

No record was kept of how many eggs were laid by virgin females retained

for life, nor were the eggs retained for hatch. However, other workers have not

reported that parthenogenesis occurs among the Phycitidae.

Time of Oviposition

Few workers have reported the time of oviposition of the lesser cornstalk

borer. Luginbill and Ainslie (1917) stated that oviposition of caged females be-

gan shortly after dusk and continued until the early morning hours. The majority

of eggs were laid during the forepart of the night. No eggs were laid diurnally

or in bright light at night. Leuck (1966) reported that caged females oviposited

shortly after dark and throughout the night.

Materials and Methods

Paper sheets were placed on screen tops of 3 mating-oviposition cages as de-

scribed under rearing techniques. The sheets were replaced every 4 hr starting at

3 PM 1 day and ending at 7 PM the following day. To determine if oviposition

occurred during the hour before the lights turned off (at 8 PM), sheets were left

on the cages from 7-8 PM at the end of the experiment. All sheets were set aside

for at least 30 hr. The eggs were then counted with the aid of a microscope.

Results and Discussion

All 3 populations oviposited over 90% of all eggs laid from 7-11 PM (92,

95, 98%). From 11 PM to 3 AM, the 3 populations oviposited 8, 3, and 2% of

all eggs laid, respectively. The remaining eggs were laid between 3 AM and 7

AM, except for 1 sterile egg laid between 7-8 PM on the 2nd day. Thus moths

oviposit primarily during the 1st 3 hr of total darkness.

Response of Adults to Sound

Sound reception by moths has attracted considerable attention in recent

years. The tympanic organs of noctuid moths are sensitive to sounds ranging

from 3-240 kc/sec with maximum sensitivity between 15-60 kc/sec (Roeder and

Treat, 1957). Tympanic nerve preparations detect bat cries at a distance of 30 m

or more (Roeder and Treat, 1960).

Insectivorous bats use ultrasonic cries to echolocate night flying insects

(Griffin, 1953; Griffin and Novick, 1955; Novick, 1965). Roeder and Treat

(1960) found that many free flying moths perform evasive behavior in the pre-

sence of bats. The same is true when moths are subjected to an artificial


approximation of bat cries (Roeder, 1962; Agee, 1967). The intensity of the sound

stimulus is directly related to the type of moth response (Roeder, 1964); diving re-

sponses are most prevalent around 75-85 db, while turning-away responses are

most prevalent around 45-55 db. No evidence indicates tympanate moths can dis-

tinguish differences in sound frequency (Roeder, 1966). It was concluded that the

evasive behavior had a selective advantage and that probably the major function

of moth tympanic organs was to warn night flying moths of approaching bats

(Roeder and Treat, 1960).

Several workers examined practical application of moth response fo sound.

Belton and Kempster (1962) broadcast ultrasonic sound at 50 kHz and obtained

more than 50% reduction of sweet corn infestation by the European corn borer,

Ostrinia nubilalis (Hl'bner). Treat (1962) captured more than twice as many tym-

panate moths in silent light traps than in light traps broadcasting recorded ultra-

sonic bat cries. Agee (1967) attempted to reduce oviposition of bollworm moths,

H. zea, and tobacco budworm moths, Heliothis virescens (F.), in cotton fields

with ultrasonic sound. He felt the negative results obtained were due to equip-

ment failure during the moths' most active periods. Payne and Shorey (1968)

found that pulsed ultrasonic sounds, especially at high intensities, reduced ovi-

position by the cabbage looper moth, T. ni, on lettuce and broccoli crops.

The tympanic organs might have other auditory or proprioceptive functions

unconcerned with bat detection (Treat, 1955), such as echo-location (Roeder and

Treat, 1957). However, Treat (1955) suggested diurnal Lepidoptera possessing

tympanic organs might have recently acquired the diurnal habit, and the organs

have persisted without survival value. On the other hand, perhaps the diurnal

fliers also fly at night when an auditory sense might be of more benefit. He men-

tioned the typically diurnal butterflies have a poorly developed auditory sense,

if it exists at all.

Roeder and Treat (1960) inferred that most moths with known auditory organs

are medium sized (10-40 mm wing span). Few of these moths escaped attack by bats

but many escaped capture.

In addition to the tympanic organs, Lepidoptera have several other organs or

structures which may assist in sound perception (Haskell, 1961). These include:

(A) Johnston's organ in the 2nd antennal segment; (B) the subgenual organs,

generally found in the proximal region of the tibiae of all legs; (C) chordotonal

sensillia, scattered about the body; and (D) hair sensillae, scattered over the body

but especially on the thorax and abdomen. All of these structures respond to 10

kc/sec or less so far as is known among the Insecta, but little research has been

done with the Lepidoptera. Functions attributed to the tympanic organs might in

fact be carried out by the above structures in combination with each other and/or

with the tympanic organs, since no one has reported bat avoidance by deafened


Further, adult Lepidoptera themselves produce sound by various means, but

little is known about their behavioral significance (Haskell, 1961; Alexander,

1967). Haskell (1961) categorized the principal types of sound producing mech-

anisms into 2 groups. The 1st group includes sounds produced by products of some

usual moth activity, as the ultrasonic sound of 15 kc/sec and possibly higher pro-

duced in the flight of Prodenia eridania. Roeder and Treat (1957) suggested the

sound might be associated with precopulatory behavior. Shorey (1964) found that


bilateral tympanectomy of both sexes of T. ni possibly reduced but did not prevent

successful copulation.

The 2nd major group includes several mechanisms such as frictional mecha-

nisms, vibrating membranes, and mechanisms directly involving air movement

(Haskell, 1961). These mechanisms include: (A) scraping raised fore and hind

wing veins together producing frequencies up to 14 kc/sec, as in the Peacock

Butterfly (Nymphalis lo); (B) rubbing wing ridges with some part of the leg, as in

many noctuid moths; (C) clicking of wing membranes which pop in and cut when

the wings are knocked together, as in Hecatesia; (D) rubbing a ribbed and a

pegged wall of an abdominal cavity together, as in certain Lymantriid male moths;

(E) forcing air thru the proboscis by means of pharynx pumping with the epipharynx

interrupting air flow, as in Acherontia atropos; and (F) possibly forcing air thru

spiracles, as in Arctia caja.

Perhaps some of the above mechanisms include clues to communication be-

tween the sexes involving sound perception by the tympanic organs, but as Alex-

ander (1967) indicates, this possibility has scarcely been investigated. In addition,

the tympanic organs sense natural sounds other than bat cries, as rustling leaves

and cricket chirps. Other functions could be served by the tympanic organs apart

from bat detection, but no evidence of the importance of such perception is avail-

able as yet (Roeder and Treat, 1961a, 1961b).

The purpose of this experiment was to determine if E. lignosellus adults re-

spond to sonic and ultrasonic sound.

Materials and Methods

A cylindrical cage of fiber glass screen and clear plastic, 6.5 cm high x 2.5

cm diam, was used to cage individual test moths. The cage top and bottom peri-

meters were plastic rings 1.5 cm and 0.5 cm wide, respectively. The screen was

sewn together along the side with thread and glued to the 2 rings. A small piece

of fitted fiber glass screen formed the bottom. The cage with a moth was inverted

into a small plastic dish with a fitted cellucotton disk saturated with 2% sucrose


Preliminary tests indicated 66-100% of moths tested nocturnally (10:30 PM to

1:30 AM) at 3-16 kHz with 3.3-20 volts of amplitude remained quiet throughout

the tests. Other moths moved about the cage and/or stroked their antennae, while

still others extended their abdomens with tone bursts and contracted the abdomens

to the normal position during silence after a tone burst. This latter activity was

used as the criteria for a positive response in the following tests since it was re-

peatable at 20-60 kHz.

Five each 2-day-old males and females were tested for behavioral response

from 2-4 PM and another set of 5 males and 5 females of the same age from 9:45-

11:00 PM. The cage was set 46 cm directly in front of a Dukane lanovac Duk-5

speaker with a power supply modified for extended frequency response. Pure tones

from 20-60 kHz in 10 kHz increments were produced with a Hewlett-Packarcf

audio oscillator model 200 CD. Three 1/2 sec tone bursts were separated by 4

sec using a General Radio tone burst generator type 1396-A timed by a Hewlett-

Packara audio oscillator model 201 C. At least 10 sec separated a tone burst

triplet from the next.

Voltages of amplitude scale settings were determined with an oscilloscope as:

20 scale setting = 1.1 volts; 30 = 1.9 volts; 40 = 3.3 volts; 50 = 6.4 volts; 60 =

13.5 volts. A General Radio sound level meter type 1551-B was used to measure

intensity on the A scale at 46 cm from the speaker. At 10 kHz, the following

amplitude scale settings were recorded in decibells: 10 = 54 db; 20 = 61 db; 30 =

66 db; 40 = 71 db; 50 = 76 db; 60 = 80 db. These sound levels correspond to the

above voltages. The loncvac tweeter was found to be linear within -- 2.5 db

between 10 and 60 kHz. Consequently the voltage readings should be convertible

to sound levels with the same scale for all frequencies.

Moths were subjected to various frequencies and amplitudes. In the 1st test,

frequencies were held constant in the following order: 40, 30, 50, and 40 kHz.

In each frequency test, amplitude dial settings were varied in the following order:

60, 40, 20, 30, and 50.

In the 2nd test, amplitude was held constant at full setting (20 volts) as fre-

quency was varied in the following order: 20, 30, 40, 50, 60, 40, 20, 30, 50,

and 60 kHz.

The cage was lighted with about 23 ft-candles during the afternoon tests.

During the evening tests, a 7 1/2 watt red light 7.5 cm distant illuminated the

cage with about 2-3 ft-candles. The room temperature was 27 4- 1 C.

Results and Discussion

In general, moths responded to high and low frequencies at high amplitudes

(Fig. 14). Females responded essentially the same during day and night, but

males were more responsive at night.

The test of bilateral tympanectomy on sound response was attempted but

abandoned due to moth size and delicacy and the tympanic organ position. The

wings, thorax and/or abdomen were usually damaged during the operation. Unlike


noctuid tympanic organs, those of E. lignosellus are located on the 1st abdominal

segment and ore covered by the metathoracic coxae. In addition, a fan of elon-

gated scales originating on the abdominal pedicel obscures the tympanal surface.

The operation was performed by anesthetizing a moth with C02, placing it on its

back, pressing with a pin on the sclerotized rim surrounding the tympanic organs,

and thrusting the pin point dorsally and posteriorly simultaneously. The operation

was essentially done in the blind. Often the tympanic membrane and scolopo-

phorous organ were still intact in moths checked later to determine operational


E. lignosellus is responsive to sound, but whether this is due to reception by

the tympanic organs was not determined. The function of the tympcnic organs in

E. lignosellus is unknown.

5 -5 o 5- -__--
I I-0
0 3 3 30

2 i 1 1
E 0 4 8 12 16 0 4 8 12 16 0 4 8 12 16

Amplitude (volts) Amplitude (volts) Amplitude (volts)
30 kHz 40 kHz 50 kHz

Diurnal response

S5 oo-- 5 -o _ _ 5 p-o-- ----o

Sc3 3) 3/

Z 1 1 1

E 0 4 8 12 16 0 4 8 12 16 0 4 8 12 16
Amplitude (volts) Amplitude (volts) Amplitude (volts)
30 kHz 40 kHz 50 kHz

Nocturnal response

> 10 O--O-- o-o 2 response
0---4 ~o response
0 8
E 6

E 4
0 20 40 60
Amplitude 20 volts

Diurnal and nocturnal
response combined

Fig. 14.-Diurnal and nocturnal response of lesser cornstalk borer adults to various
amplitudes and frequencies.


Need for basic research on the reproductive biology of the lesser cornstalk borer,

Elasmopalpus lignosellus (Zeller) (Lepidoptera: Phycitidae) prompted this research.

The borer reportedly attacks 62 host plants representing 14 plant families, but host

records may be incorrect due to similar feeding habits of other species.

A rearing technique was developed. Sixty to 80 pupae were obtained per 100

eggs. Total time from egg to adult was 24-28 days. The colony was reared for 34

months or approximately 32 generations. Ninety-five percent of pupae obtained

were normally formed. Lightly sclerotized aberrations occurred on the venter of 5%

of pupae obtained. Approximately 92% and 78% emergence of normal adults was

obtained from normal and aberrant pupae respectively.

The male and female reproductive systems, including spermatophore morphology

and position in the bursa, were studied and compared with other Lepidoptera. Color-

less fluid in the 1st secretary area of the primary simplex of the male indicated a

mating (=spermatophore transfer) less than 24 hr previously. Virgin 1-6-day-old

males had translucent yellow simplex fluid, and males that mated 2-5 days pre-

viously had transparent yellow simplex fluid. Within 24 hr after mating, simplex

fluid in 3-day-old mated males changed from transparent colorless to transparent

yellow. Color of spermatophores representing 3 successive matings was clear trans-

parent. Thus 1st matings were indistinguishable from subsequent matings on the


basis of spermatophore color. Females had no full-sized eggs at emergence, but

might have them present in the calyx, lateral oviducts, and/or common oviduct as

well as in the ovarioles within 1-2 days after emergence.

The abdominal tympanic organs were studied and compared with the general

pyraloid description. The tympani were ventrally and anteriorly located on the 1st

abdominal segment.

Mating occurred in 40-dr vials but not in 4-dr vials. In the 40-dr vials no

significant differences in mating success occurred in respect to cage position, cage

top materials, and fed versus unfed moths for a single mating per pair. Fed moths

were more likely to mote again than unfed moths.

Mating behavior was observed, including pair formation, courtship, time of

coupling, duration of copulation, uncoupling of motes, and post copulatory activity.

Pair formation and courtship behavior included activities suggestive of olfactory

stimuli. Mating occurred from 1:40 AM to 6:40 AM. Males mated with approxi-

mately equal frequency when caged for 1 day with 1, 2, 3, or 4 females. One- to

6-day-old moths mated equally well. Complete bilateral antennectomy of males

inhibited mating.

Virgin moles lived 42.4 4 1.7 days (mean standard error), mated males 24.2

4 1.5 days, virgin females 37.6 4 1.8 days, and mated females 18.1 -_ 1.7 days.

Males passed 7.2 4 0.8 sperratophores each and females accepted 1.7 4 0.2 sperma-

tophores each in a lifetime. There was no significant correlation between longev-

ity and spermatophores passed. Females laid 419.5 4 14.7 eggs each of which

5.5% were sterile and retained 8 eggs at death. Oviposition began the 2nd day of

caging with males, and decreasing numbers of eggs were laid daily throughout the


oviposition period. Females oviposited 48% of all eggs laid by the 4th day of

caging with males. Females laying more than the average percent of sterile eggs.

tended to delay oviposition more than 1 day, to retain more than 10 eggs at death,

and/or oviposit non-decreasing daily numbers of eggs during the oviposition period.

There was no significant correlation among longevity, spermatophores accepted,

total eggs laid, sterile eggs laid, and length of oviposition period. Correlation

between number of eggs laid and number of fertile eggs was significant at the 1%

level (rs8089). Correlation between the number of spermatophores accepted and

the number of eggs retained at death was significant at the 5% level (r-5006).

Moths responded to sound of high and low frequencies at high amplitudes.

Males were more responsive nocturnally than diurnally, but females showed little

differential response.


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