Data are presented on the diapause and the seasonal emergence patterns of the adults of a univoltine Callosamia promethea population from northern Indiana and a partially bivoltine population from central Illinois. At Urbana, Illinois, the median emergence date of adults from overwintering Illinois pupae was about a month earlier than that of adults from overwintering Indiana pupae. Illinois samples had a much longer emergence period than Indiana samples. Indiana samples showed a slight tendency toward a bimodal emergence pattern, a few individuals emerging in late May and the rest emerging as a tightly synchronized group from late June to mid-July. Early emerging lIIinois moths produced mostly non.diapausing progeny, but the proportion of diapausing progeny increased as the season progressed. Some females produced both diapausing and non· diapausing progeny. Adults from non-diapausing pupae from early August to early September

Sternburg, J. G

Waldbauer, G. P

English

ValpoScholar

The Great Lakes Entomologist 
Volume 17 
Number 3 - Fall 1984 Number 3 - Fall 1984 Article 8 
October 1984 
Diapause and Emergence Patterns in Univoltine and Bivol Tine 
Populations of Promethea (Lepidoptera: Saturniidae) 
J. G. Sternburg 
University of Illinois 
G. P. Waldbauer 
University of Illinois 
Follow this and additional works at: https://scholar.valpo.edu/tgle 
 Part of the Entomology Commons 
Recommended Citation 
Sternburg, J. G. and Waldbauer, G. P. 1984. "Diapause and Emergence Patterns in Univoltine and Bivol Tine 
Populations of Promethea (Lepidoptera: Saturniidae)," The Great Lakes Entomologist, vol 17 (3) 
Available at: https://scholar.valpo.edu/tgle/vol17/iss3/8 
This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. 
It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. 
For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. 
1984 THE GREAT LAKES ENTOMOLOGIST 155 
DIAPAUSE AND EMERGENCE PATTERNS IN UNIVOLTINE 

AND BIVOL TINE POPULATIONS OF 

PROMETHEA (LEPIDOPTERA: SATURNIIDAE) 

J. G. Sternburg and G. P. Waldbauerl 
ABSTRACT 
Data are presented on the diapause and the seasonal emergence patterns of the adults of 
a univoltine Callosamia promethea population from northern Indiana and a partially 
bivoltine population from central Illinois. At Urbana, Illinois, the median emergence date 
of 
adults from overwintering Illinois pupae was about a month earlier than that 
of adults 
from overwintering Indiana pupae. Illinois samples had a much longer emergence period 
than Indiana samples. Indiana samples showed a slight tendency toward a bimodal 
emergence pattern, a few individuals emerging in late May and the rest emerging as a 
tightly synchronized group from late June to mid-July. Early emerging lIIinois moths 
produced mostly non.diapausing progeny, but the proportion of diapausing progeny 
increased as the season progressed. Some females produced both diapausing and non· 
diapausing progeny. Adults from non-diapausing pupae from early August to 
early September. 
The promethea moth, Call samia promefhea (Drury) (Lepidoptera: Saturniidael, 
overwinters as a pupa in a conspicuous cocoon that hangs from a twig of the host tree or 
shrub. It is one of the most abundant and commonly collected saturniids of eastern North 
America, but surprisingly little information on its biology has been published, and few 
quantitative data on its voltinism r on the seasonal pattern of adult eclosion are available. 
Ferguson (1972) cited a few published accounts and personal communications which 
indicate that promethea is univoltine in the northern part of its range (Michigan and most 
of 
New England), possibly bivoltine 
in Rhode Island and New York, and certainly at least 
partially bivoltine from southern New Jersey and St. Louis, Missouri, south. Worth 
(1970) found it to be partially bivoltine in Cape May County, New Jersey. and noted that 
one overwintered female can produce both diapausing and non·diapausing progeny. Rau 
and Rau (1912, 1914) presented data on the emergence in the vicinity of St. Louis, 
Missouri, of promethea from native cocoons and cocoons from the vicinity of Fall River, 
Massachusetts. 
We present data on the diapause and adult seasonal emergence patterns of a univoltine 
promethea population from northern Indiana and of a partially bivoltine population from 
central Illinois, which are separated by no more than 175 km and Ie 18' of latitude. 
MATERIALS AND METHODS 
Cocoons were coIlected from young sassafras (Sassafras albidum (NutL) Nees) or 
black cherry (P unus serOfina Ehrh.) trees near the following towns in the months 
indicated: Medaryville, Indiana (41°4' N latitude); March 1969, 1972, and 1973, 
December 1969, January 1974, and February 1975; Reynolds, Indiana (40°46'): March 
1972; Charleston, Illinois (39°28'): April 1970 and 1974, March 1972 and 1975, and 
January 1973. The cocoons were then held at Urbana, Illinois (40°6') in a screened 
'Department of Entomology, University of Illinois. Urbana, lL 61801. 
1
Sternburg and Waldbauer: Diapause and Emergence Patterns in Univoltine and Bivol Tine Popu
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156 THE GREAT LAKES ENTOMOLOGIST Vol. 17, No.3 
outdoor insectary and chccked daily for adult emergence from late April until emergence 
ended in July. 
The adults probably did not emerge from cocoons held at Urbana on the same dates they 
would have in their native areas. However, moving the cocoons to an intermediate area 
(Urbana), where all cocoons experienced identical weather conditions, had the advantage 
of 
revealing inherent differences 
in the seasonal responses of the Medaryville and 
Charleston populations without the complicating effects of differences in weather. The 
emergence of these two populations at Urbana differed i  every year of the study and was 
always characteristic of their geographic strain. Moreover, pupae of the M daryville and 
Charleston strains that had been reared at Urbana produced adults in synchrony with 
pupae that had been wild-collected in those areas. 
The Medaryville and Charleston samples of 1970 and 1972 were tested by chi-square 
analysis (I d.f. continuity corrected) for differences in the seasonal distribution of 
emerging adults. A common median emergence date was determined by combining the 
two samples. A 2 x 2 contingency table was then constructed on the basis of the number of 
individuals from each area that emerged before or after this common median date. 
In 
1970 and 1973 to 1975 some 
of the females that emerged from wild Medaryville or 
Charleston cocoons were paired with males from the same locality. (More information on 
these pairings appcars in Table I, Fig. 3, and the text.) Their progeny were reared 
outdoors under nylon mesh sleeves covering black cherry saplings. The resulting cocoons 
were held in cages in the insectary and checked daily for adult emergence. After 
emergence stopped in September the remaining cocoons were examined to eliminate dead 
individuals. Heavy, non-rattling cocoons were assumed to contain diapausing pupae, a 
judgement confirmed by the emergence of adults from the great majority of these cocoons 
the following summer. 
RESULTS AND DISCUSSION 
On the whole, adults emerged from overwintering northern Medaryville cocoons much 
later than from overwintering southern Charleston cocoons. The median emergence dates 
at Urbana for samples from these two areas were significantly different in both 1970 
(Figs. I and 2) and 1972 2) (for 1970x" = 13.0andp 0.005; for 1972 x" = 57.8 
and p < 0.005). 
There was a slight tendency toward a bimodal emergence pattern in the Medaryville 
population (Figs. I and 2, Table I), with adults of the early mode. seen only i 1969 and 
1970 when the Medaryville collections were exceptionally large. emerging from mid-to 
late May (Fig. I, Table I). The adults of the late mode constituted about 99'1C of the 
emergence and had median emergence dates that ranged from 30 June in 1970 to II July 
in 
1972 (Table I). The late mode was tightly synchronized (Figs. I and 2), encompassing 
a mean 
of only 27.3 days over six years and ranging from 21 days in 1969 to 33 days in
1975 
(Table I). Promethea from Reynolds (34 km south 
of Medaryville) were available 
only i  1972; they in synchrony with the Medaryville adults of that year (Fig. 2). 
Adults of the Charleston population had median emergence dates that ranged from 30 
May in 1970 to 15 June in 1975 (Fig. 2). about one month earlier than the Medaryville 
adults. The emergence pattern of the Charleston samples varied. but was almost always 
much more extended than that of the Medaryville samples. During five years the entire 
emergence period encompassed a mean of 47.8 days. In 1970 and 1972 it encompassed 59 
and 66 days, respectively, but from 1973 to 1975 only 39. 32 and 43 days. respectively 
(Fig. 2). The duration of the emergence period appears to be inversely correlated with the 
mean temperatures for May and June, but this correlation cannot be shown to be 
significant on the basis of the available data. 
The voltinism of the two promethea populations was determined by rearing at Urbana 
the progeny of some wild-collected adults of the Medaryville late emergence mode and 
the progeny f some wild-collected adults that represented almost the entire emergence 
period of the Charleston sample. In all four years that we made these rearings the 
Charleston popUlation was partially bivoltine. The Medaryville population. at least as 
2
The Great Lakes Entomologist, Vol. 17, No. 3 [1984], Art. 8
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1984 THE GREAT LAKES ENTOMOLOGJST 157 
Table 1. Emergence of adult promethea from cocoons collected near Medaryville and 
transferred o a screened outdoor insectary at Urbana, Illinois. 
First Emergence Group Second Emergence Group 
Emergence Dates: Emergence Dates: Number 
Year Emerging Inclusive Median 
1969 1 31/5 31/5 260 26/6-1617 5;7 
1970 10 19/5-26/5 2215 555 17/6-J417 30/6 
1972 
0 
61 20/6-1917 1117 
1973 0 83 21/6-1417 917 
1974 0 65 2116-1817 9 7 
1975 
0 50 2516-2817 1/7 
30 I=cf 
o=~ 20 
Medaryville 1969 n= 153cfcf. 1069910 
8 12 16 20 24 
n=314cfcf, 25199 
20 
10 
4 8 12 16 
MAY JUNE JULY 
Fig. I" The emergence at Urbana, Illinois, of adult promelhea from oH~rwint(~rjn 
been collected in the vicinity of Medaryville, Indiana, Ihe preceding winter. cocoons were 
held in a screened outdoor insectary at Urbana. 
Medaryville 1970 
3
Sternburg and Waldbauer: Diapause and Emergence Patterns in Univoltine and Bivol Tine Popu
Published by ValpoScholar, 1984
158 THE GREAT LAKES ENTOMOLOGIST Vol. \7, No.3 
5 Medaryville 1972 n=35crcr, 2699 
Median Emergence Dale = July II 
tOl Reynolds 1972 n=29crcr, 36~9 
5 Median Emergence Date:; July 12 
~ _________________________________~L___LUL_..LU~~iLLU~LU 
Charleston 1970 n=12crcr, 1899~ 51 
Median Emergence Dale:: May 
30 
~ L-" h JIII'lMlo 'lo om. 0 ~D 
~ 5t Charleston 1972 n=2Scrcr, 2099 
~ ... JI Med;an Emergence Dale ~ June 5 

~ L-_____.."OLL-LOL-__O~__IILI~~___lUJiL________~_=_~uD~DuDl~~.____iDL-__LLD 
_ _ Charleston 1973 n::;3Scrcr, 
2299 

.... 
Med;an Emergence Dale 
~ 

-<:)()Q.) E: June 8 5f 
~ ~___________~.~~~:~~~IO~~~~u~______~u~________ 
'"'- 5 ~ Charleston 1974 n::; Iserer, 8~9 

I Median Emergence Date;: June 5 

I 0 •... ~ .-fl.& • 
Charleston 1975 n= 77c:!c:!, 4599 
~ _ Med;an Emergence Dale ~ June 15J 
2"29~ ~~~~iJLP~~~loO--~14--~18--~2213 17 21 
MAY JUNE JULY 
Fig. 2. The emergence at Urbana, Illinois, of adult promethea from overwintering cocoons that had 
been collected the preceding year in the vicinity of the indicated towns. The cocoons were held in a 
screened outdoor insectary at Urbana. 
judged by progeny from its major emergence mode, was entirely univoltine with all of the 
F, progeny diapausing as pupae. We do not know if adults of the early Medaryville 
emergence mode produce non-diapausing progeny. Although the early mode is small, it is 
evolutionarily interesting. 
In 1975 we reared the progeny of 21 pairs of wild-collected Charleston adults. The 
dates on which these pairs mated are indicated in Figure 3. Oviposition began on the 
evening of the day of mating. (Hereafter the progeny of one pair will be referred to as a sib 
group.) As shown in Figure 3, the proportion of the progeny that entered diapause 
increased as the season progressed. Eggs laid on or before 4 June yielded about 5% or 
fewer diapausing individuals. Eggs laid from 14 June to 22 June yielded up to about 20% 
diapausers. Eggs laid on or after 24 June yielded at least 80% diapausing individuals. Of 
the 21 sib groups included in Figure 3, 12 included both diapausers and non-diapausers, 
two included only diapausers, and six (two of 30 May, two of I June and two of 4 June) 
included only non-diapausers. 
Table 2 presents data on the development of the non-diapausing individuals of all of the 
1975 Charleston sib groups that included 40 or more non-diapausers. The mean develop­
ment time from the beginning of oviposition to the emergence of the adult was 67.9 days 
for all larvae, but varied with sib group, ranging from 60 to 75 days. The development 
rate accelerated as the mean temperature increased with the advancing season. The fast 
development rate of sib groups J and K in the face of decreasing temperature is worth 
noting because it suggests that late hatching larvae may be ableto compensate for low 
temperatures during development. However, the data are so meager that they do not 
warrant further analysis. 
4
The Great Lakes Entomologist, Vol. 17, No. 3 [1984], Art. 8
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1984 THE GREAT LAKES ENTOMOLOGIST 159 
100 
DATE PARENTS MATEO 
Fig. 3. The percent of diapausing pupae in 2[ sib groups of promethea as it varied with the date on 
which the parents had mated. This is the day on which oviposition began. The parents emerged at 
Urbana from cocoons collected in the vicinity of Charleston in February of [975. Above each dot 
are indicated the total number of pupae (both diapausing and non-diapausing) and in parentheses 
the number of sib groups. 
Figure 4 shows the emergence dates of the adults that developed from the non­
diapausing pupae included in Figure 3. The apparent but artifactual bimodality of the 
emergence results from the fact that we rearcd no larvae from eggs laid between 3 and 13 
June. Emergence began on 2 August and continued until 8 September. We have no 
detailed data on the development or survival of the second generation produced by these 
adults. However, over the years we have found that the progeny of early emerging first 
generation adults survive to pupate while the progeny of adults that emerge in late August 
and September are not likely to survive. The latter grow slowly because of the usually low 
temperatures of September, and possibly because of declining food plant quality, and 
often do not manage to pupate before freezing weather occurs. In 1974 late larvae of the 
second generation were killed by an unusually early frost that ocurred on 2 October. 
Sex ratios f the adults were skewed in favor o  males (Figs. 1, 2, and 4) with the 
exception of the small 1970 Reynolds and Charleston samples. We have no explanation 
for this, but differential mortality during winter is not likely to be the reason because the 
Charleston FI progeny of 1975, which did not overwinter, also had a sex ratio strongly 
skewed in favor of males. Rau and Rau (1912) found a similarly skewed sex ratio at St. 
Louis, Missouri, with locally collected cocoons producing 116 males but only 67 females. 
It is of 
some interest to compare promethea's seasonal history with that 
of the closely 
related cecropia moth, Hyalophora cecropia (L.), which is also abundant throughout most 
of 
the United States and southern Canada east 
of the Great Plains. Cecropia seems to be 
univoltine throughout its range. All cecropia populations thus far sampled have exhibited 
5
Sternburg and Waldbauer: Diapause and Emergence Patterns in Univoltine and Bivol Tine Popu
Published by ValpoScholar, 1984
160 THE GREAT LAKES ENTOMOLOGIST Vol. 17, No.3 
Table 2. Origin, diapause and total development time of eleven sib groups· f the progeny 
of 
Charleston promethea. The adults were collected as pupae near Charleston 
in March of 
1975. These progeny were reared at Urbana in the summcr of 1975. Egg laying began on 
the evening of the day on which the parents mated. 
Median Adult 
Date 
MeanSib Date 

Parents Mated No. % 

A 26/5 

B 27/5 

C 30/5 

D 30/5 

E 30/5 

F V6 

G 4/6 

H 14/6 

I 20/6 

J 2216 

K 30/6 
III 
48 
47 
67 
100 
63 
64 
84 
66 
145 
55 
97.3 
98.0 
78.3 
100.0 
100.0 
100.0 
100.0 
78.5 
79.5 
93.5 47 0
9/8 61
9/8 
[0/8 l(}/8 
lQ,'8 
5/8 
19/8 
25/8 
23/8 
29/8 
75 
71 
71 
72 
72 
70 
62 
66 
66 2 
60 
72.5 
72.5 
72.7 
72.8 
72.8 
73.0 
73.6 
74.5 
75.2 
74.8 
74.6 
"Only sib groups with 40 
or more non-diapausers are included. See Figure 3 for 

emergence data for other groups. 

bMean of daily mean temperatures from egg hatch to emergence. 

80 Charleston 1975 
Fe 
progeny of non-diapausers 
70 
10 
n=5500'0', 40299 
14 3013579 
AUGUST SEPTEMBER 
Fig. 4. The emergence of the adult progeny of some of the non-diapausing promethea that emerged at 
Urbana in 1975 from cocoons that had been collected in the vicinity of Charleston the previous 
winter. 
6
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1984 THE GREAT LAKES ENTOMOLOGIST 161 
a bimodal adult emergence pattern. At Urb n , I linois, the early emerging group appears 
in 
late May and includes from 4.7% to 24.4% 
of the total emergenee. The second 
emergence group appears in late June (Waldbauer and Sternburg 1973. Waldbauer 1978, 
Sternburg and Waldbauer 1978). 
Promethea differs from cecropia most notably by being bivolline in the southern part of 
its range. However, the seasonal history of the univoltine Medaryville population is very 
similar to th tof cecropia, including a tendency to exhibit a bimodal emergence pattern. 
LITERATURE CITED 
Ferguson, D. C. 1972. Bombycoidea, Saturniidae (in part). p. 155-275 in R. B. 
Dominick, et al. (eds.). (l971~2)  The Moths of America north of Mexico, Fasc. 20. 
2B. Classey, London. 
Rau, P. and N. Rau. 1912. Longevity in saturniid moths: an experimental study. J. Exp. 
Zooi. 12:179~204. 
~--. 
1914. Longevity 
in saturniid moths and its relation to the function of reproduc­
tion. Trans. Acad. Sci. St. Louis 23:1~77. 
Sternburg, J. G. and G. P. Waldbauer. 1978. Phenological adaptations in diapause 
termination by cecropia from different latitudes. Entomoi. Exp. App\. 23:48~54. 
Waldbauer, G. P. 1978. Phenological adaptation and the polymodal emergence patterns 
of 
insects. p. 
127~144 ill H. Dingle (ed.). Evolution of insect migration and diapause. 
Springer-Verlag. New York. 
Waldbauer. G. P. and J. G. Sternburg. 1973. Polymorphic termination of diapause by 
cecropia: genetic and geographical aspects. BioI. Bull. 145:627-641. 
Worth, C. B. 1970. Studies of partially double-brooded silkmoths in May County. 
New Jersey (Lepidoptera: Saturniidae). Entomol. News 81 :36-37. 
7
Sternburg and Waldbauer: Diapause and Emergence Patterns in Univoltine and Bivol Tine Popu
Published by ValpoScholar, 1984


Diapause and Emergence Patterns in Univoltine and Bivol Tine Populations of Promethea (Lepidoptera: Saturniidae)

Valparaiso University

The Great Lakes Entomologist Volume 17 Number 3 - Fall 1984 Number 3 - Fall 1984 Article 8 October 1984 Diapause and Emergence Patterns in Univoltine and Bivol Tine Populations of Promethea (Lepidoptera: Saturniidae) J. G. Sternburg University of Illinois G. P. Waldbauer University of Illinois Follow this and additional works at: https://scholar.valpo.edu/tgle  Part of the Entomology Commons Recommended Citation Sternburg, J. G. and Waldbauer, G. P. 1984. "Diapause and Emergence Patterns in Univoltine and Bivol Tine Populations of Promethea (Lepidoptera: Saturniidae)," The Great Lakes Entomologist, vol 17 (3) Available at: https://scholar.valpo.edu/tgle/vol17/iss3/8 This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. 1984 THE GREAT LAKES ENTOMOLOGIST 155 DIAPAUSE AND EMERGENCE PATTERNS IN UNIVOLTINE AND BIVOL TINE POPULATIONS OF PROMETHEA (LEPIDOPTERA: SATURNIIDAE) J. G. Sternburg and G. P. Waldbauerl ABSTRACT Data are presented on the diapause and the seasonal emergence patterns of the adults of a univoltine Callosamia promethea population from northern Indiana and a partially bivoltine population from central Illinois. At Urbana, Illinois, the median emergence date of adults from overwintering Illinois pupae was about a month earlier than that of adults from overwintering Indiana pupae. Illinois samples had a much longer emergence period than Indiana samples. Indiana samples showed a slight tendency toward a bimodal emergence pattern, a few individuals emerging in late May and the rest emerging as a tightly synchronized group from late June to mid-July. Early emerging lIIinois moths produced mostly non.diapausing progeny, but the proportion of diapausing progeny increased as the season progressed. Some females produced both diapausing and non· diapausing progeny. Adults from non-diapausing pupae from early August to early September. The promethea moth, Call samia promefhea (Drury) (Lepidoptera: Saturniidael, overwinters as a pupa in a conspicuous cocoon that hangs from a twig of the host tree or shrub. It is one of the most abundant and commonly collected saturniids of eastern North America, but surprisingly little information on its biology has been published, and few quantitative data on its voltinism r on the seasonal pattern of adult eclosion are available. Ferguson (1972) cited a few published accounts and personal communications which indicate that promethea is univoltine in the northern part of its range (Michigan and most of New England), possibly bivoltine in Rhode Island and New York, and certainly at least partially bivoltine from southern New Jersey and St. Louis, Missouri, south. Worth (1970) found it to be partially bivoltine in Cape May County, New Jersey. and noted that one overwintered female can produce both diapausing and non·diapausing progeny. Rau and Rau (1912, 1914) presented data on the emergence in the vicinity of St. Louis, Missouri, of promethea from native cocoons and cocoons from the vicinity of Fall River, Massachusetts. We present data on the diapause and adult seasonal emergence patterns of a univoltine promethea population from northern Indiana and of a partially bivoltine population from central Illinois, which are separated by no more than 175 km and Ie 18' of latitude. MATERIALS AND METHODS Cocoons were coIlected from young sassafras (Sassafras albidum (NutL) Nees) or black cherry (P unus serOfina Ehrh.) trees near the following towns in the months indicated: Medaryville, Indiana (41°4' N latitude); March 1969, 1972, and 1973, December 1969, January 1974, and February 1975; Reynolds, Indiana (40°46'): March 1972; Charleston, Illinois (39°28'): April 1970 and 1974, March 1972 and 1975, and January 1973. The cocoons were then held at Urbana, Illinois (40°6') in a screened 'Department of Entomology, University of Illinois. Urbana, lL 61801. 1Sternburg and Waldbauer: Diapause and Emergence Patterns in Univoltine and Bivol Tine PopuPublished by ValpoScholar, 1984156 THE GREAT LAKES ENTOMOLOGIST Vol. 17, No.3 outdoor insectary and chccked daily for adult emergence from late April until emergence ended in July. The adults probably did not emerge from cocoons held at Urbana on the same dates they would have in their native areas. However, moving the cocoons to an intermediate area (Urbana), where all cocoons experienced identical weather conditions, had the advantage of revealing inherent differences in the seasonal responses of the Medaryville and Charleston populations without the complicating effects of differences in weather. The emergence of these two populations at Urbana differed i  every year of the study and was always characteristic of their geographic strain. Moreover, pupae of the M daryville and Charleston strains that had been reared at Urbana produced adults in synchrony with pupae that had been wild-collected in those areas. The Medaryville and Charleston samples of 1970 and 1972 were tested by chi-square analysis (I d.f. continuity corrected) for differences in the seasonal distribution of emerging adults. A common median emergence date was determined by combining the two samples. A 2 x 2 contingency table was then constructed on the basis of the number of individuals from each area that emerged before or after this common median date. In 1970 and 1973 to 1975 some of the females that emerged from wild Medaryville or Charleston cocoons were paired with males from the same locality. (More information on these pairings appcars in Table I, Fig. 3, and the text.) Their progeny were reared outdoors under nylon mesh sleeves covering black cherry saplings. The resulting cocoons were held in cages in the insectary and checked daily for adult emergence. After emergence stopped in September the remaining cocoons were examined to eliminate dead individuals. Heavy, non-rattling cocoons were assumed to contain diapausing pupae, a judgement confirmed by the emergence of adults from the great majority of these cocoons the following summer. RESULTS AND DISCUSSION On the whole, adults emerged from overwintering northern Medaryville cocoons much later than from overwintering southern Charleston cocoons. The median emergence dates at Urbana for samples from these two areas were significantly different in both 1970 (Figs. I and 2) and 1972 2) (for 1970x" = 13.0andp 0.005; for 1972 x" = 57.8 and p < 0.005). There was a slight tendency toward a bimodal emergence pattern in the Medaryville population (Figs. I and 2, Table I), with adults of the early mode. seen only i 1969 and 1970 when the Medaryville collections were exceptionally large. emerging from mid-to late May (Fig. I, Table I). The adults of the late mode constituted about 99'1C of the emergence and had median emergence dates that ranged from 30 June in 1970 to II July in 1972 (Table I). The late mode was tightly synchronized (Figs. I and 2), encompassing a mean of only 27.3 days over six years and ranging from 21 days in 1969 to 33 days in1975 (Table I). Promethea from Reynolds (34 km south of Medaryville) were available only i  1972; they in synchrony with the Medaryville adults of that year (Fig. 2). Adults of the Charleston population had median emergence dates that ranged from 30 May in 1970 to 15 June in 1975 (Fig. 2). about one month earlier than the Medaryville adults. The emergence pattern of the Charleston samples varied. but was almost always much more extended than that of the Medaryville samples. During five years the entire emergence period encompassed a mean of 47.8 days. In 1970 and 1972 it encompassed 59 and 66 days, respectively, but from 1973 to 1975 only 39. 32 and 43 days. respectively (Fig. 2). The duration of the emergence period appears to be inversely correlated with the mean temperatures for May and June, but this correlation cannot be shown to be significant on the basis of the available data. The voltinism of the two promethea populations was determined by rearing at Urbana the progeny of some wild-collected adults of the Medaryville late emergence mode and the progeny f some wild-collected adults that represented almost the entire emergence period of the Charleston sample. In all four years that we made these rearings the Charleston popUlation was partially bivoltine. The Medaryville population. at least as 2The Great Lakes Entomologist, Vol. 17, No. 3 [1984], Art. 8https://scholar.valpo.edu/tgle/vol17/iss3/81984 THE GREAT LAKES ENTOMOLOGJST 157 Table 1. Emergence of adult promethea from cocoons collected near Medaryville and transferred o a screened outdoor insectary at Urbana, Illinois. First Emergence Group Second Emergence Group Emergence Dates: Emergence Dates: Number Year Emerging Inclusive Median 1969 1 31/5 31/5 260 26/6-1617 5;7 1970 10 19/5-26/5 2215 555 17/6-J417 30/6 1972 0 61 20/6-1917 1117 1973 0 83 21/6-1417 917 1974 0 65 2116-1817 9 7 1975 0 50 2516-2817 1/7 30 I=cf o=~ 20 Medaryville 1969 n= 153cfcf. 1069910 8 12 16 20 24 n=314cfcf, 25199 20 10 4 8 12 16 MAY JUNE JULY Fig. I" The emergence at Urbana, Illinois, of adult promelhea from oH~rwint(~rjn been collected in the vicinity of Medaryville, Indiana, Ihe preceding winter. cocoons were held in a screened outdoor insectary at Urbana. Medaryville 1970 3Sternburg and Waldbauer: Diapause and Emergence Patterns in Univoltine and Bivol Tine PopuPublished by ValpoScholar, 1984158 THE GREAT LAKES ENTOMOLOGIST Vol. \7, No.3 5 Medaryville 1972 n=35crcr, 2699 Median Emergence Dale = July II tOl Reynolds 1972 n=29crcr, 36~9 5 Median Emergence Date:; July 12 ~ _________________________________~L___LUL_..LU~~iLLU~LU Charleston 1970 n=12crcr, 1899~ 51 Median Emergence Dale:: May 30 ~ L-" h JIII'lMlo 'lo om. 0 ~D ~ 5t Charleston 1972 n=2Scrcr, 2099 ~ ... JI Med;an Emergence Dale ~ June 5 ~ L-_____.."OLL-LOL-__O~__IILI~~___lUJiL________~_=_~uD~DuDl~~.____iDL-__LLD _ _ Charleston 1973 n::;3Scrcr, 2299 .... Med;an Emergence Dale ~ -<:)()Q.) E: June 8 5f ~ ~___________~.~~~:~~~IO~~~~u~______~u~________ '"'- 5 ~ Charleston 1974 n::; Iserer, 8~9 I Median Emergence Date;: June 5 I 0 •... ~ .-fl.& • Charleston 1975 n= 77c:!c:!, 4599 ~ _ Med;an Emergence Dale ~ June 15J 2"29~ ~~~~iJLP~~~loO--~14--~18--~2213 17 21 MAY JUNE JULY Fig. 2. The emergence at Urbana, Illinois, of adult promethea from overwintering cocoons that had been collected the preceding year in the vicinity of the indicated towns. The cocoons were held in a screened outdoor insectary at Urbana. judged by progeny from its major emergence mode, was entirely univoltine with all of the F, progeny diapausing as pupae. We do not know if adults of the early Medaryville emergence mode produce non-diapausing progeny. Although the early mode is small, it is evolutionarily interesting. In 1975 we reared the progeny of 21 pairs of wild-collected Charleston adults. The dates on which these pairs mated are indicated in Figure 3. Oviposition began on the evening of the day of mating. (Hereafter the progeny of one pair will be referred to as a sib group.) As shown in Figure 3, the proportion of the progeny that entered diapause increased as the season progressed. Eggs laid on or before 4 June yielded about 5% or fewer diapausing individuals. Eggs laid from 14 June to 22 June yielded up to about 20% diapausers. Eggs laid on or after 24 June yielded at least 80% diapausing individuals. Of the 21 sib groups included in Figure 3, 12 included both diapausers and non-diapausers, two included only diapausers, and six (two of 30 May, two of I June and two of 4 June) included only non-diapausers. Table 2 presents data on the development of the non-diapausing individuals of all of the 1975 Charleston sib groups that included 40 or more non-diapausers. The mean develop­ment time from the beginning of oviposition to the emergence of the adult was 67.9 days for all larvae, but varied with sib group, ranging from 60 to 75 days. The development rate accelerated as the mean temperature increased with the advancing season. The fast development rate of sib groups J and K in the face of decreasing temperature is worth noting because it suggests that late hatching larvae may be ableto compensate for low temperatures during development. However, the data are so meager that they do not warrant further analysis. 4The Great Lakes Entomologist, Vol. 17, No. 3 [1984], Art. 8https://scholar.valpo.edu/tgle/vol17/iss3/81984 THE GREAT LAKES ENTOMOLOGIST 159 100 DATE PARENTS MATEO Fig. 3. The percent of diapausing pupae in 2[ sib groups of promethea as it varied with the date on which the parents had mated. This is the day on which oviposition began. The parents emerged at Urbana from cocoons collected in the vicinity of Charleston in February of [975. Above each dot are indicated the total number of pupae (both diapausing and non-diapausing) and in parentheses the number of sib groups. Figure 4 shows the emergence dates of the adults that developed from the non­diapausing pupae included in Figure 3. The apparent but artifactual bimodality of the emergence results from the fact that we rearcd no larvae from eggs laid between 3 and 13 June. Emergence began on 2 August and continued until 8 September. We have no detailed data on the development or survival of the second generation produced by these adults. However, over the years we have found that the progeny of early emerging first generation adults survive to pupate while the progeny of adults that emerge in late August and September are not likely to survive. The latter grow slowly because of the usually low temperatures of September, and possibly because of declining food plant quality, and often do not manage to pupate before freezing weather occurs. In 1974 late larvae of the second generation were killed by an unusually early frost that ocurred on 2 October. Sex ratios f the adults were skewed in favor o  males (Figs. 1, 2, and 4) with the exception of the small 1970 Reynolds and Charleston samples. We have no explanation for this, but differential mortality during winter is not likely to be the reason because the Charleston FI progeny of 1975, which did not overwinter, also had a sex ratio strongly skewed in favor of males. Rau and Rau (1912) found a similarly skewed sex ratio at St. Louis, Missouri, with locally collected cocoons producing 116 males but only 67 females. It is of some interest to compare promethea's seasonal history with that of the closely related cecropia moth, Hyalophora cecropia (L.), which is also abundant throughout most of the United States and southern Canada east of the Great Plains. Cecropia seems to be univoltine throughout its range. All cecropia populations thus far sampled have exhibited 5Sternburg and Waldbauer: Diapause and Emergence Patterns in Univoltine and Bivol Tine PopuPublished by ValpoScholar, 1984160 THE GREAT LAKES ENTOMOLOGIST Vol. 17, No.3 Table 2. Origin, diapause and total development time of eleven sib groups· f the progeny of Charleston promethea. The adults were collected as pupae near Charleston in March of 1975. These progeny were reared at Urbana in the summcr of 1975. Egg laying began on the evening of the day on which the parents mated. Median Adult Date MeanSib Date Parents Mated No. % A 26/5 B 27/5 C 30/5 D 30/5 E 30/5 F V6 G 4/6 H 14/6 I 20/6 J 2216 K 30/6 III 48 47 67 100 63 64 84 66 145 55 97.3 98.0 78.3 100.0 100.0 100.0 100.0 78.5 79.5 93.5 47 09/8 619/8 [0/8 l(}/8 lQ,'8 5/8 19/8 25/8 23/8 29/8 75 71 71 72 72 70 62 66 66 2 60 72.5 72.5 72.7 72.8 72.8 73.0 73.6 74.5 75.2 74.8 74.6 "Only sib groups with 40 or more non-diapausers are included. See Figure 3 for emergence data for other groups. bMean of daily mean temperatures from egg hatch to emergence. 80 Charleston 1975 Fe progeny of non-diapausers 70 10 n=5500'0', 40299 14 3013579 AUGUST SEPTEMBER Fig. 4. The emergence of the adult progeny of some of the non-diapausing promethea that emerged at Urbana in 1975 from cocoons that had been collected in the vicinity of Charleston the previous winter. 6The Great Lakes Entomologist, Vol. 17, No. 3 [1984], Art. 8https://scholar.valpo.edu/tgle/vol17/iss3/81984 THE GREAT LAKES ENTOMOLOGIST 161 a bimodal adult emergence pattern. At Urb n , I linois, the early emerging group appears in late May and includes from 4.7% to 24.4% of the total emergenee. The second emergence group appears in late June (Waldbauer and Sternburg 1973. Waldbauer 1978, Sternburg and Waldbauer 1978). Promethea differs from cecropia most notably by being bivolline in the southern part of its range. However, the seasonal history of the univoltine Medaryville population is very similar to th tof cecropia, including a tendency to exhibit a bimodal emergence pattern. LITERATURE CITED Ferguson, D. C. 1972. Bombycoidea, Saturniidae (in part). p. 155-275 in R. B. Dominick, et al. (eds.). (l971~2)  The Moths of America north of Mexico, Fasc. 20. 2B. Classey, London. Rau, P. and N. Rau. 1912. Longevity in saturniid moths: an experimental study. J. Exp. Zooi. 12:179~204. ~--. 1914. Longevity in saturniid moths and its relation to the function of reproduc­tion. Trans. Acad. Sci. St. Louis 23:1~77. Sternburg, J. G. and G. P. Waldbauer. 1978. Phenological adaptations in diapause termination by cecropia from different latitudes. Entomoi. Exp. App\. 23:48~54. Waldbauer, G. P. 1978. Phenological adaptation and the polymodal emergence patterns of insects. p. 127~144 ill H. Dingle (ed.). Evolution of insect migration and diapause. Springer-Verlag. New York. Waldbauer. G. P. and J. G. Sternburg. 1973. Polymorphic termination of diapause by cecropia: genetic and geographical aspects. BioI. Bull. 145:627-641. Worth, C. B. 1970. Studies of partially double-brooded silkmoths in May County. New Jersey (Lepidoptera: Saturniidae). Entomol. News 81 :36-37. 7Sternburg and Waldbauer: Diapause and Emergence Patterns in Univoltine and Bivol Tine PopuPublished by ValpoScholar, 1984

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Diapause and Emergence Patterns in Univoltine and Bivol Tine Populations of Promethea (Lepidoptera: Saturniidae)

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