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LIBRARY OF THE
UNIVERSITY OF ILLINOIS
AT URBANA-CHAMPAIGN

no.6G@ - 299

avat en meee

SURVEY

|

THE DISTRIBUTION OF
PERIODICAL CICADAS IN ILLINOIS

Lewis J. Stannard, Jr.

|

\
Biological Notes No. 91
i

‘ILLINOIS NATURAL HISTORY SURVEY

URBANA, ILLINOIS e FEBRUARY, 1975

‘STATE OF ILLINOIS
‘DEPARTMENT OF REGISTRATION AND EDUCATION
NATURAL HISTORY SURVEY DIVISION

The Distribution of Periodical Cicadas in Illinois

For decades, entomologists have relied upon
Marlatt’s (1907) compilation of the distribution of
the broods of the periodical cicada to forecast emer-
gences of these insects. Such forecasts are especially
important to persons concerned with protecting trees
and shrubs. Unfortunately, as will be shown in this
report, many of Marlatt’s records are in error. In
their place, a more accurate picture of cicada distribu-
tion in Illinois, as observed over the past 10 years, is
given here. Additional surveillance of periodical ci-
cadas could be continued profitably to pinpoint exact
boundaries of their ranges in some of the central
counties of our state, to determine the rates of their
dispersal to new areas or extirpation from original
areas, and to obtain information on the possibility of
introgressive hybridization between broods.

To orchardists, nurserymen, and_ horticulturists,
periodical cicadas are more than mere curious and
interesting insects. Even though they occur infre-
quently (once every 13 or 17 years), they may dam-
age more than 95 percent of the terminal shoots
of young fruit trees (Hamilton 1962) or ruin the
shapes of specimen trees or choice shrubs. When one
considers that as many as 20,000 cicadas may emerge
from beneath one apple tree, it is easy to understand
how so many twigs can be destroyed during the
cicadas’ egg-laying process (Hamilton 1962). Trees
whose terminal shoots are killed by cicadas usually
recover by epicormic branching, according to my
observations, but fruit production in orchards can be
severely curtailed, causing substantial economic loss.

This report is presented primarily as an aid to
fruit growers in making accurate predictions of emer-
gences of periodical cicadas and as a contribution to
our basic knowledge of these unusual insects.

ACKNOWLEDGMENTS

I wish to express my appreciation to the staff of
the Illinois Natural History Survey, extension ento-
mologists of the University of Illinois, county exten-
sion advisers of the state of Illinois, and the many
persons in our state who have helped to collect speci-
mens and have shared their observations on the dis-
tribution of cicadas over the past 10 years. Without
their assistance the state could not have been covered
thoroughly in the approximately 3 weeks of the par-

This paper is published by authority of the State of Illinois,
TRS Ch. 127, Par. 58.12, and is a contribution from the Section
of Faunistic Surveys and Insect Identification of the Illinois
Natural History Survey, where Dr. Stannard is a Taxonomist.

Lewis J. Stannard, Jr.

ticular years when these insects exist above ground
as adults.

My particular thanks are extended to Drs. Thomas
E. Moore and Henry S. Dybas for their advice,
suggestions, and many favors, especially to Dr. Dybas
for reviewing the manuscript. I am further obliged
to Mr. Wilmer D. Zehr, who photographed the
specimen appearing on the cover; to Mr. Lloyd
Le Mere, who prepared the maps; to Mrs. Bernice
Sweeney, who typed the manuscript; and to Mr.
Robert M. Zewadski, who edited it for publication.

THE ILLINOIS BROODS

With the exception of woods in certain areas that
are predominantly sandy (in extreme northeastern
Lake County, in eastern Iroquois and Kankakee
counties, and in areas in Lee, Ogle, Mason, and a
few other counties) almost every wooded section
of Illinois is inhabited by a brood of periodical
cicadas. Of the five Illinois broods, three have 17-year
life cycles and two have 13-year life cycles. A report
of their distributions, based mostly on data gathered
over the 10 years from 1963 to 1973, is presented
here. Documentary notes for this report and the
specimens are kept in the collections of the Illinois
Natural History Survey (INHS). The research for this
report was essentially completed in 1973, and the
report was submitted for publication in December
1973.

HISTORICAL RECORDS

One of the first entomologists to record Illinois
broods of periodical cicadas was Asa Fitch in 1856.
Fitch thought, as did everyone at that time, that all
cicada broods in the USA had life cycles of 17 years’
duration. The first brood he mentioned as being from
Illinois (“Southern Illinois”) was the 13-year Great
Southern Brood (Marlatt’s XIX), which emerged in
1855 simultaneously with an adjacent eastern brood
(Marlatt’s XIV). Fitch lumped these together as
his “third” brood, later analyzed by Walsh & Riley
(1868). The other Illinois brood mentioned by Fitch
was the 17-year Northern Illinois Brood (Marlatt’s
XIII) as his “sixth” USA brood. He stated that this
brood extended across northern Illinois, ranging as
far south as Peoria, in 1854.

Shortly after the appearance of Fitch’s work, Cyrus
Thomas, the “father” of the Illinois Natural History
Survey, learned of records of a third brood of cicadas

4

in Illinois, the 13-year Lower Mississippi River Valley
Brood (Marlatt’s XXIII), which emerged in Union
and Jackson counties in 1859. Thomas thought that
this brood also had a 17-year life cycle (Thomas
1865:458-459 ).

In 1868 Benjamin Walsh and C. V. Riley raised
the number of Illinois broods to four, adding the
17-year Iowan Brood (Marlatt’s IIL). These authors
also suggested that another brood, Marlatt’s IV, might
occur in Illinois, but this has not proved to be the
case. Further, they outlined the range of the Great
Southern Brood (Marlatt’s XIX) in Illinois, and with
few exceptions the range is the same today, accord-
ing to my 1972 findings.

In the same year, 1868, Riley reported that not
all broods had 17-year life cycles but that some had
13-year life cycles. Riley’s discovery was made dur-
ing his study of the Great Southern Brood (Marlatt’s
XIX), wherein he noted an 1803 record from Alton,
Illinois. According to Marlatt (1907), Dr. D. L.
Phares of Mississippi probably was the very first, in
1845, to “announce the 13-year period for the south-
ern broods,” but because the article was published
in a newspaper with local circulation, this notice
did not come to the immediate attention of entomolo-
gists.

In the following year (1869) Riley published his
first annual report on the insects of Missouri and
expanded his and Walsh’s previous treatment of
periodical cicadas by incorporating information from
a manuscript written by Dr. Gideon B. Smith of
Maryland, then deceased. (This manuscript was pub-
lished in its entirety by Marlatt in 1898.) From the
16 broods estimated to exist in the USA in 1868,
Riley increased the list to 22 broods, changing the
numbers of all broods except Brood I. Riley continued
his surveillance of periodical cicadas, publishing on
them and including Illinois records, until 1894 just
before his untimely death from a fall in 1895.

By 1869, therefore, the literature referred to broods
numbered separately and differently by Fitch (1856),
Walsh & Riley (1868), and Riley (1869). The records
included well-documented data as well as mere recol-
lections, some of which were considered questionable
at the time and some of which have since proved
to be in error.

A couple of years later in 1871, William LeBaron
(1872) wrote that “one of the special duties of the
State Entomologist of Illinois, in the season of 1871,
[was] to determine, as nearly as possible, the range
of the present brood, and to make a record of it,
which may be consulted by those who may take an
interest in this matter, seventeen years hence.” His
detailed report of the distribution of this brood, the

Northern Illinois Brood (Marlatt’s XIII), fits well
within the broad limits mentioned by Fitch in 1856
and confirmed by my own survey in 1973. LeBaron
personally noted the absence of this brood in Mason
County, supposedly because of some effects of the
sandy soils in this county. However, a Mr. J. Cochrane
of Havana, Mason County, convinced LeBaron that
a brood emerged in large numbers in Mason County
in 1859 or 1860, which LeBaron thought might really
be 1861, the year when the Iowan Brood (Marlatt’s
III) emerged. This supposed emergence, inexactly
recalled some 10 years after its alleged occurrence,
does not fit with recent data and probably should
be discarded as questionable evidence.

It was not until 1885, when Riley made special
inquiry of many persons, that the 17-year Great
Eastern Brood (Marlatt’s X) was proved to occur in
Illinois at the eastern border and became the fifth
Illinois brood. Some scattered precocious or late
emergences of out-of-season broods undoubtedly were
included in these Illinois records, but in general,
Riley's limitations of the range of this brood in Illi-
nois are the same as those noted in recent years. A
sixth Illinois brood, mentioned by Riley in 1885, is
probably incorrect, according to my data.

U.S. government entomologists L. O. Howard,
C. L. Marlatt, F. M. Webster, M. V. Slingerland, and
others became active in the survey of the USA cicada
broods in the 1890's and early 1900's. At the Bureau
of Entomology, Washington, D.C., at first under
Riley, Marlatt eventually took over as the principal
compiler of the ranges of the broods. In 1907 (re-
issued in 1923) Marlatt published what was then the
most complete and definitive work on the periodical —
cicada. In it he compiled all the principal literature
and records for each brood, including, unfortunately,
the questionable records. He increased the number
of broods to 30 even though he considered some
doubtful. It was as if Marlatt wanted the total num-
ber of broods to equal the sum of the two life cycles
(17 + 13), and to achieve this equality, he appeared
willing to include any record he could find. Further-
more, he renumbered the broods differently than had
Riley in 1869. Generally, Marlatt’s numbered desig-
nations have been accepted and are in use today.
Instead of 30 broods, Alexander & Moore (1962)
believe that there may be no more than 18 valid
broods in the eastern USA.

S. A. Forbes, head of the predecessor organizations
of the Illinois Natural History Survey, his staff,
teachers, and others continued to gather data on the
Illinois broods and supply Riley, Howard, Marlatt,
and others with information. Most of the early
cicada specimens, if any were kept, are no longer in
the Survey’s collections. The Survey has only a few

specimens from 1894, a few from the first decade
of the 1900's, and a few collected in central Illinois
over the next 50 years.

In 1956 the Northern Illinois Brood (Marlatt’s
XIII) again emerged in high numbers and inspired
Henry S. Dybas of the Field Museum of Natural
History, Chicago; Thomas E. Moore, then at the
Illinois Natural History Survey, Urbana; and Richard
D. Alexander, formerly of White Heath, Illinois, to
begin new studies on cicadas. Their discoveries caused
renewed interest in these insects, opening new types
of inquiry and leading to new conclusions on the
nature and origin of the possible species involved and
the broods. They, along with Monte Lloyd, D.
Dwight Davis, and James Heath, made and are
making in-depth studies on the exact niches of the
species, their songs, and their possible dispersal after
deglaciation.

EXCLUDED BROODS

Several broods besides those whose distribution is
treated here were purported by Marlatt and others
to occur in Illinois. One of these, Marlatt’s XIV,
was said to extend across the northern border of
Illinois. Although observations on periodical cicadas
of Illinois have not been regularly made until recent
times, the lack of records of this brood in the INHS
collections has some significance. Alexander & Moore
in 1957 (an emergence year for Brood XIV) did record
single specimens in Illinois and Iowa, but they con-
sidered these cicadas to be stragglers from the previ-
ous year’s emergence of the Northern Illinois Brood
(Marlatt’s XIII) (Alexander & Moore 1962:18). Very
few cicadas were found in intensive searches in 1974,
and this fact, coupled with the negative evidence of
previous years, would indicate that Brood XIV does
not, and probably never did, occur in Illinois.

Another brood (Marlatt’s XII) reported by Mar-
latt (1907) to be in Illinois almost certainly does
not exist in our state, if indeed it is a valid brood
anywhere in the USA. In 1972, when this brood was
to emerge, I made repeated trips to Jo Daviess
County and neighboring counties, and enlisted the
help of naturalists, state park rangers, and landowners
in attempts to locate populations of this alleged brood.
No cicadas were found. Marlatt, himself, felt that this
was a doubtful brood and reported that Forbes had
failed to locate it in northwestern Illinois. Probably
the records of this brood in Illinois were based on
precocious cicadas of the Northern Illinois Brood
(Marlatt’s XIII) which emerged a year early.

Marlatt’s I was recorded by Marlatt (1907) as
being questionably present in Madison County, but
the Illinois Natural History Survey has no records or
specimens of this brood. Alexander & Moore (1962)

5

did not list any Illinois records of this brood, which
they studied in detail in the East in 1961.

Marlatt’s VI was purported to occur in Illinois
from localities where cicadas were said to have
emerged in abundance in 1898. In the S.A. Forbes
correspondence of 1898 in the archives section of
the University of Illinois Library is a request from
L. O. Howard of the Bureau of Entomology, Wash-
ington, D.C., for cicada information. This request
prompted Forbes to send a circular letter to teachers
and superintendents of schools asking for data on
cicadas emerging in 1898. Besides Forbes, Howard
asked other correspondents for information on these
cicadas. By June 20, 1898, Howard informed Forbes
that he had received a large amount of data from
Illinois. The records received by Forbes and Howard
from Crawford, Jackson, Jasper, Lawrence, Perry,
Pulaski, Union, Wabash, and Wayne counties can be
referred to the Lower Mississippi River Valley Brood
(Marlatt’s XXIII), and this distribution fits well with
our present-day records. The other records reported
by Howard, especially those supposedly of Marlatt’s
VI in central Illinois, must be considered doubtful,
as we have no specimens in the Natural History
Survey collection from this region in 1898 or the
following years during which this brood appeared.
It should have reappeared in 1966 if it really exists
in Illinois, but no observers at the Illinois Natural
History Survey have any notes or recollections of
this brood’s emerging at that time.

THE SPECIES OF PERIODICAL CICADAS

During the years when the surveillance of periodi-
cal cicadas was dominated by Riley and Marlatt, it
was generally thought that two races existed, the
17-year cicada, Tibicen (Cicada) septendecim (Lin-
naeus), and the 18-year cicada, Tibicen (Cicada)
tredecim Riley, with a dwarf form known as cassini
Fisher. Walsh argued (Marlatt 1907:17; Lloyd &
Dybas 1966b), and even corresponded with Charles
Darwin on the subject, that the 13-year race was an
incipient species because the 13-year race and the
17-year race occasionally have opportunities to inter-
breed; yet no intermediate emergences (14-, 15-, or
16-year intervals) result.

In 1931 Beamer, in 1958 Alexander & Moore (see
also Moore & Alexander 1958), and in 1962 Dybas
& Lloyd, on the basis of morphological and behavioral
distinctiveness, independently arrived at the conclu-
sion that Magicada septendecim and M. cassini were
separate species. In 1962 Alexander & Moore recog-
nized six full species, M. septendecim, M. cassini, and
M. septendecula Alexander and Moore for the 17-year
broods, and M. tredecim, M. tredecassini Alexander
and Moore, and M. tredecula Alexander and Moore

6

for the 13-year broods. Apparently no differences
exist between the matching pairs of species of the
13- and 17-year broods; they are merely more or
less isolated from each other for 13-17 generations.

In Illinois, at least, one 13-year brood, the Great
Southern Brood (Marlatt’s XIX), is not as isolated
from 17-year broods as might be expected. Along
the border of the range of this brood, contacts with
all of three 17-year broods may occur within 221
years, and contact with one of these three 17-year
broods could and possibly does occur every 65 years
(five generations) or 78 years (six generations), as
indicated in Table 1. If such contacts are made,
enough hybridization may occur to prevent isolation
of the “incipient species.”

TABLE 1. — Dates of simultaneous emergences of a 13-
year brood and each of three 17-year broods of periodical
cicadas in Illinois. (Mathematically, 65 and 78 are functions
of 13.)

Broods and Years of Emergences

Great Northern Great Iowan
Witerval din Southern Illinois Eastern
Veans (XIX) (XII) AP) (111)
(13-year) (17-year ) (17-year ) (17-year)
1972 1973 1970 1963
1582 1582
65 1647 1647
78 1725 1725
78 1808 1808
221
65 1868 1868
78 1946 1946
78 2024 2024
221
65 2089 2089
78 2167 2167
78 2245 2245
221

If the matching pairs of 13- and 17-year cicadas
are merely phases of the same species, three full
species might remain. Each would have its own
niche, the small M. cassini living on roots of bottom-
land trees, the large M. septendecim living on roots
of upland trees, and M. septendecula, intermediate
between the first two and rarer, developing primarily
on hickory and walnut roots (Dybas & Davis 1962;
Dybas & Lloyd 1974).

It seems hardly possible that M. septendecim is
a single species with three forms, resulting from
development in separate and different habitats, and
with two phases — 13-year and 17-year — primarily
resulting from environmental influences. However,
the order Homoptera, to which these cicadas belong,
is well known for having species that develop highly

divergent forms in response to theiz feeding sub-
strates. Some scale insects, for example Aspidiotus
ancylus (Putnam), produce divergent forms according
to whether they feed on bark or leaves or on certain
trees and vines; these forms once were considered
to belong to separate genera (Stannard 1965). Some
leafhoppers produce forms with radically different
types of genitalia, depending on temperature in-
fluences (Miiller 1957). Even so, the possibility that
there is just one species with forms having their own
songs, their own times of day for singing, preferences
for mating with their own kinds, and their own feed-
ing niches appears remote in the light of our present
knowledge and contradicts generally accepted con-
cepts of species.

In this report only the broods will be considered;
the nature of the species and their evolution have
been well discussed by Lloyd & Dybas (1966a and
1966b) and Dybas & Lloyd (1974).

STRAGGLER CICADAS

Stragglers from the 13- and 17-year sequence do
occur with some frequency. Usually, according to
most records, only a few individuals emerge at these
off times, and there seems little chance for mating
and production of progeny. In 1969, however, a large
number of stragglers emerged in the Chicago area.
This emergence was of further singularity because it
occurred at the close of a 13-year interval in a
region where only a 17-year brood was known. Dybas
(1969) made an extensive study of these “13-year
stragglers” and concluded that he may have had a
“ringside seat” along the evolutionary pathway on —
which 18-year cicadas were derived from 17-year
cicadas. He assumed that the cicadas of this par- —
ticular emergence probably would not develop into
a new brood because of the usually cold climate of
Chicago. Dybas postulated that the heat effect of the
city may have had some influence on these particular
stragglers, causing them to emerge so early.

Stragglers that emerge in the fall of the year can
be positively identified as deviates, but those that
emerge in the regular season (May and June) need
to be analyzed with considerable care. These spring
stragglers seem to have provided the basis for all
the false broods listed by Marlatt and others. Most
stragglers emerge early, in the year before the main
brood is due.

Supposed Illinois Stragglers

Unless otherwise stated, data refer to single speci-
mens in the INHS collection.

1904. Riverside, Cook County. Possibly not 1907,
as given by Alexander & Moore (1962). The
last digit appears to be a 4 rather than a 7. This

is a possible l-year-early emergence of the 17-
year Northern Illinois Brood (Marlatt’s XIII)
of 1905.

. Urbana, Champaign County, University Woods,
September 6. Rocky Branch, Clarksville, Clark
County, June 24. These are possibly 1-year-
early emergences of the 13-year Great Southern
Brood (Marlatt’s XIX) of 1933.

1957. Sullivan, Moultrie County, “late in season,”
H. B. Cunningham, six specimens. This is pos-
sibly a 1%2-year-early emergence of the 13-year
Great Southern Brood (Marlatt’s XIX) of 1959.

1969. Lisle, DuPage County, June 6, L. J. Stannard,
| just emerged at edge of a lowland woods in
Morton Arboretum. Chicago Heights, Cook
County, June 11, H. B. Petty. Chicago area,
many specimens reported to the Natural His-
tory Survey extension staff. (See Dybas 1969
for extensive list of localities in the Chicago
region.) These are assumed to be 4-year-early
emergences of the 17-year Northern Illinois
Brood (Marlatt’s XIII) of 1973.

Barry, Pike County, June 9, J. Cruttenden,
several specimens. Tentatively assigned to
M. tredecassini by T. E. Moore (personal com-
munication 1971). These are probably 1-year-
early emergences of the 13-year Great Southern
Brood (Marlatt’s XIX) of 1972. Mr. Cruttenden
recalls the presence of this brood in the area
in 1959.

Lisle, DuPage County, October 12, J. Appleby,
one adult next to its shed skin, emerged after
flood in Morton Arboretum. This is possibly a
half-year-early emergence of the 17-year North-
ern Illinois Brood (Marlatt’s XIII) of 1973.

Mahomet, Champaign County, Nettie Hart
Memorial Woods, June 6, M. W. Sanderson.
This is a possible l-year-late emergence of the
13-year Great Southern Brood (Marlatt’s XIX)
which emerged in 1972.

Lisle, DuPage County, May 29, J. Appleby,
one adult on bush. Ohio, Lee County, May 23,
Gene R. Kritsky, one adult in flight hit car.
These are probably l-year-late emergences of
the 17-year Northern Illinois Brood (Marlatt’s
XIII).

| Other supposed stragglers in the USA have been
| listed by Alexander & Moore (1962) and in the Chi-
cago area by Lloyd & Dybas (1966b).

11971.

, 1972.

| 1973.

/ 1974.

DISTRIBUTION OF
THE BROODS OF ILLINOIS

| Because many of Marlatt’s broods probably do
| not exist and because several numbering systems, each

1

differing from the others, have been used, the Illinois
broods listed here are designated by geographical
names with the corresponding Marlatt numbers for
easy reference. These geographical names should
be more meaningful than numbers and indicate re-
lationships with populations outside the state.

The lowan Brood ( Marlatt’s III)

The Iowan Brood has a 17-year cycle and most
recently emerged in 1963. Records (Fig. 1) were ob-
tained from May 26, 1963 along the Spoon River,

Fig. 1. — Distribution of periodical cicadas in Illinois.
The two upper enclosed areas show the locations of the
Iowan Brood (Marlatt’s III), and the two lower enclosed
areas indicate the locations of the Lower Mississippi River
Valley Brood (Marlatt’s XXIII). Black dots indicate posi-
tive records of adult specimens, skins, holes in the ground,
flagging tree branches, or singing. Circles indicate negative
records in areas carefully searched.

8

Fulton County, to June 28 in De Witt County. Sing-
ing was heard until June 28, also in De Witt County,
and flagging (wilted branches that were girdled in
the egg-laying process) was noticed on the same date
in that county.

Apparently this brood is disjunct in Illinois, the
western counties which it inhabits being Brown,
Fulton, Henderson, Knox, McDonough, Schuyler, and
Warren, and the eastern counties being Champaign,
De Witt, and Piatt. Intervening counties, particularly
Logan and Mason, did not seem to have populations
of these cicadas. In the western counties mentioned
and De Witt County large numbers of cicadas
emerged, whereas Champaign and Piatt counties had
only limited emergences.

This brood must have emerged simultaneously, in
1946, in some instances in adjacent areas or even in
the same woods, with the Great Southern Brood
(Marlatt’s XIX), and these broods will again emerge
simultaneously in 2167. Unfortunately, we have no
records of the 1946 emergences in the INHS collection.
Both broods may occupy the same woods in Cham-
paign County if our records are correctly interpreted.
Woods along the Spoon River, Knox County, should
be carefully observed in the future to determine
whether some of the woods harboring the Iowan
Brood also support populations of the Great Southern
Brood.

In 1963 Clarence E. White, an INHS entomologist,
collected specimens and reported a large emergence
in woods at the junction of Illinois 150 and the Spoon
River. In 1972 Kent R. Buffington reported in a letter
a large emergence in woods north of that area along
the Spoon River near Truro, or Williamsfield, as that
town is now called. The 1963 population could be
assigned to the Iowan Brood and that of 1972 to the
Great Southern Brood unless the 1972 emergence
was made up of an unusually high number of strag-
glers of the 1973 Northern Illinois Brood that is
known to have colonies nearby.

The Lower Mississippi River Valley Brood
(Marlatt’s XXIII)

The Lower Mississippi River Valley Brood has
a 13-year cycle and last emerged in 1963, the year of
the Iowan Brood’s most recent emergence. Records
in 1963 (Fig. 1) were obtained from late May until
the middle of June. In Illinois this brood is also
disjunct, being confined to Alexander, Jackson, Perry,
Pulaski, and Union counties in the southwest and
to Crawford, Jasper, Lawrence, and Wabash counties
in the southeast. Several Illinois counties harboring
no cicadas of this brood intervene between these
populations, but the distribution of this brood prob-
ably continues to the south in Kentucky and Missouri.

A wide gap exists between the locations of this brood
and those of the Iowan Brood within the state.

The Great Eastern Brood (Marlatt’s X)

The Great Eastern Brood has a 17-year cycle and
most recently emerged in 1970. Although reported
to be well distributed along the eastern border of
Illinois and even in southern Illinois (Marlatt 1907),
in 1970 this brood was found in only a few counties
(Vermilion, Edgar, and Clark) despite careful searches
elsewhere (Fig. 2). Adults were found from May 21
at Kickapoo State Park, Vermilion County, until June
30, when a small chorus was heard by Dr. R. W.
Larimore at nearby Fairmount. A shed skin was found

Fig. 2. — Distribution of the Great Eastern Brood (Mar-

latt’s X) of periodical cicadas in Illinois. Black dots
indicate positive records of adult specimens, skins, holes
in the ground, flagging tree branches, or singing. Circles
indicate negative records in areas carefully searched.

in Urbana, Champaign County, on a Liriodendron
tree, a non-native tree, planted there 8 years previ-
ously. Seventeen years earlier in 1953 when this
brood emerged, a straggler was also found in Urbana
by Dr. R. J. Dysart on August 12. Despite the scanty
records in Champaign County, it is possible that the
Great Eastern Brood occurred and still persists in
small numbers in the Big Grove of Urbana and that
eastern Champaign County should be included in the
list of counties inhabited by this brood.

The 17-year Great Eastern Brood (Marlatt’s X)
‘must have emerged in Illinois adjacent to and at
the same time as the 13-year Great Southern Brood
(Marlatt’s XIX) in 1647 and 1868, and they should ap-
pear together again in 2089. Furthermore, the Great
Eastern Brood must have emerged adjacent to and
at the same time as the 13-year Lower Mississippi
River Valley Brood (Marlatt’s XXIII) along the border
of Clark and Crawford counties in 1664 and 1885,
,and they should occur together again in 2106.

According to Marlatt (1907) and as reinterpreted
‘by Dybas (1970), this brood has three main but
almost certainly disjunct centers: a broad portion
‘of Indiana and western Ohio, a wide area pri-
‘marily bordering the Mason-Dixon line in Maryland
and Pennsylvania, and an area in the southern Ap-
-palachians.

The Great Southern Brood (Marlatt’s XIX)

The Great Southern Brood has a 13-year cycle
and emerged last in 1972. This brood emerges in
abundant numbers largely outside the limits of the
Wisconsin moraine, except through the east-central
region of the state, and outside the areas occupied
by the Great Eastern Brood (Marlatt’s X) and the
Lower Mississippi River Valley Brood (Marlatt’s
XXIII) (Fig. 3). An isolated colony of “extremely
sheavy populations of cicadas” was reported to us by
‘K. R. Buffington on May 18-20, 1972 along the Spoon
River near Truro, now called Williamsfield, in Knox
County. Along the upper Sangamon River in Cham-
‘paign County both the 13-year Great Southern Brood
and adventive or relict colonies of the 17-year Iowan
Brood may occur together. In these woodlands in
western Champaign County, the Great Southern
Brood emerged in greater numbers in 1972 than did
‘the supposed Iowan Brood in 1963.

The 1972 INHS records show that the Great
Southern Brood started to emerge as adults as early as
‘May 14 in Pope County, on May 20 in Olney in
Richland County, on May 23 at Fox Ridge State
Park near Charleston in Coles County, and on May
25 in Piatt County. Singing continued as late as
June 30 at Robert Allerton Park near Monticello in
‘Piatt County.

Fig. 3. — Distribution of the Great Southern Brood
(Marlatt’s XIX) of periodical cicadas in Illinois. Black
dots indicate positive records of adult specimens, skins, holes
in the ground, flagging tree branches, or singing. Circles
indicate negative records in areas carefully searched.

In Illinois the 13-year Great Southern Brood prob-
ably emerged adjacent to and at the same time as the
17-year Iowan Brood in 1725 and in 1946, and they
should emerge together again in 2167. In the Spring-
field area the Great Southern Brood probably emerged
at the same time as and adjacent to the 17-year
Northern Illinois Brood in 1582 and in 1803, and they
should emerge together again in 2024. The Great
Southern Brood probably emerged simultaneously
with the 17-year Great Eastern Brood in 1647 and
1868, and they should do so again in 2089. The
opportunity for this 13-year brood to interbreed with
these 17-year broods appears highly likely to occur

10

every 65 or 78 years at some part of the Great
Southern Brood’s total range in Illinois, but only once
every 221 years at each specific locality.

A limited number of specimens of this brood were
collected in the twin cities of Champaign-Urbana in
1959 and in 1972. They were taken even in those
parts of the cities which were originally prairie or were
cultivated land less than 25-50 years previously but
which are now studded with trees. Moderate singing
also was heard by competent observers in both of
these years. It would seem, therefore, that colonizing
cicadas succeeded in expanding their range at least a
few miles into new parklands and that the population
level for survival need not be extremely high.

Although bird populations are low in some parts
of these cities, where birds are present, cicadas are
eagerly sought. In one instance a dozen live cicadas
were placed on a hedge in Urbana near a bird-feeding
tray. Within 1 minute a blue jay appeared and seized
one of the sluggish cicadas. Shortly, this jay returned
and was joined by another. All, or at least 11, of
the cicadas were quickly taken by the jays; the fate
of the last cicada was not determined in the con-
fusion of the jays’ visits to the hedge. Other birds,
including hawks, were found to have fed heavily on
these cicadas in southern Illinois (Dr. R. R. Graber
personal communication 1972).

Unpublished reports by Dr. G. W. Bennett indi-
cate that game fish benefited from the abundance of
this brood in 1972. Fishes at Fox Ridge State Park,
Coles County, fed voraciously on these insects. Cicadas
at that site weighed from about % gram to nearly a
full gram.

The Northern Illinois Brood (Marlatt’s XII)

The Northern Illinois Brood has a 17-year cycle,
and its most recent emergence was in 1973. Possibly
because a wet, cool spring delayed the emergence,
the earliest 1973 records of this brood (Fig. 4) were
not taken until May 31 (Tazewell and Sangamon
counties) and June 2 (Cook County). Singing was
heard in Tazewell County at the end of May and in
Jo Daviess, Cook, and Lake counties as late as June
20.

This brood occurs primarily on the Wisconsin
glacial drift area except for areas in east-central
Illinois. These east-central Illinois regions are occu-
pied by the 13-year Great Southern Brood. Several
competent observers noted the absence of this brood
from the Zion sand areas in Lake County, and my
associates and I failed to find any specimens in the
sand areas of Iroquois, Mason, and Lee counties.

The Northern Illinois Brood ranges south to Car-
penter Park, north of Springfield, and to Petersburg.

Fig. 4. — Distribution of the Northern Illinois Brood
(Marlatt’s XIII) of periodical cicadas in Illinois. Black
dots indicate positive records of adult specimens, skins,
holes in the ground, flagging tree branches, or singing.
Circles indicate negative records in areas carefully searched.

Woods south of Springfield and woods near Me-
chanicsburg showed no evidence of cicadas (speci-
mens, singing, skins, or holes in the ground). During
the preceding year, 1972, the Great Southern Brood
emerged in these woods (A. L. Koelling personal com-
munication 1973). At the Springfield and Mechanics-
burg area, at least, this brood and the 13-year Great
Southern Brood probably emerged simultaneously in
1582 and 1803, and will do so again in 2024 and 2245.

The persistence of this brood in old parts of cities
was noted in Chicago and Rockford. Mrs. Barbara
Fell noted a few skins in her back yard at 819 North

:

:

Main Street, Rockford, indicating the survival of this
brood, despite low numbers, over the past 136 or so
years of human occupancy of that city.

In a woods at Castle Rock, Ogle County, the
eastern portion contained no cicadas, whereas the
western portion, having the same terrain but possibly
less sand in the soil, contained a good singing popula-
tion. There I found adults, skins, and holes in the
ground. This observation and others bear out the
contention that each woods is not necessarily uni-
formly inhabited.

FUTURE EMERGENCES OF
PERIODICAL CICADAS IN ILLINOIS

Future twentieth-century emergences of periodical
cicadas in Illinois are shown in Table 2.

Taple 2. — Future twentieth-century emergences of
periodical cicadas in L[llinois.

Year of Cycle
Emergence Brood in Years
1976 Lower Mississippi River Valley Brood 13

(Marlatt’s XXIII)
1980 Iowan Brood (Marlatt’s III) 17
1985 Great Southern Brood (Marlatt’s XIX) 13
1987 Great Eastern Brood (Marlatt’s X) ab
1989 Lower Mississippi River Valley Brood 13
(Marlatt’s XXIII)
1990 Northern Illinois Brood (Marlatt’s XIII) aly
1997 Iowan Brood (Marlatt’s III) 17
1998 Great Southern Brood (Marlatt’s XIX) 13
DISCUSSION

A composite map of the distribution of the Illinois
broods of periodical cicadas is shown in Fig. 5. The
borders of the range of each brood are only approxi-
mate except in a few regions, as critical areas and
woods which should have been put under close sur-
veillance for more precise information could not be
recognized until after two or three emergences had
been surveyed. In general, the distributions of these
broods fit nicely with the distributional patterns of
other organisms viewed in relation to geological
events. Most of the region occupied by the Northern
Illinois Brood lies within the Wisconsin glacial plain.
The Iowan Brood, except for the region inhabited
by the disjunct population in De Witt, Piatt, and
Champaign counties, occupies a western spur on
eroded hills of the northern part of the Illinoian glacial
plain. The Great Southern Brood, except for the
east-central Illinois extension and the corridor in the
Shawnee Hills, is mostly on Illinoian glacial plains

onto which most of our southern biota also extends.

The Great Eastern Brood occupies an area which
supports many other relict or adventive eastern spe-

11

%

SS

Fig. 5. — Distribution of periodical cicadas in Illinois.
The ranges of the five Illinois broods are shown on the map.
Each brood is identified by Marlatt’s number.

cies: beech, tulip poplar, and some fishes and sala-
manders. The Lower Mississippi River Valley Brood
occurs for a considerable part in the region where the
bald cypress also meets its northern limits.

Occupation of a woods by two or more broods
is extremely rare, according to my data. Woods can
be almost adjacent, but each woods usually supports
one brood only. Sand areas are usually, if not always,
devoid of cicadas.

The opportunity for 13-year and 17-year broods
to meet and hybridize may occur every 65 or 78 years
within the total range of the majority of the periodical
cicadas of Illinois. It is highly possible that no more

12

than three species exist, each closely regulated by
climatic influences producing 13- or 17-year strains,
operating under either-or genetic controls.

LITERATURE CITED

ALEXANDER, R. D., and T. E. Moore. 1958. Studies on the
acoustical behavior of seventeen year cicadas (Homop-
tera: Cicadidae: Magicicada). Ohio Journal of Science
58 (2) :107-127.

5 Ea! 1962. The evolutionary relation-
ships of 17-year and 13-year cicadas, and three new spe-
cies (Homoptera, Cicadidae, Magicicada). University of
Michigan Museum of Zoology Miscellaneous Publication
121, 59 p.

Beamer, R, H, 1931. Notes on the 17-year cicada in Kansas.
Kansas Entomological Society Journal 4(3) :53-58.

Dypas, H. S. 1969. The 17-year cicada: A four-year “mis-
take’? Field Museum of Natural History Bulletin 40(8):
10-12.

. 1970. Poulation explosion — 17-year locust style.
Field Museum of Natural History Bulletin 41(5):11-13.

, and D. D. Davis. 1962. A population census of
seventeen-year periodical cicadas (Homoptera: Cicadi-
dae: Magicicada). Ecology 43(3) :432-444.

, and M. Lloyd. 1962. Isolation by habitat in two
synchronized species of periodical cicadas (Homoptera:
Cicadidae: Magicicada). Ecology 43(38):444-459,

, and) 2 ess, 1974.) Dhe habitats of. 1?%-year
periodical cicadas (Homoptera: Cicadidae: Magicicada
spp.) Ecological Monographs 44(3) :279-324.

Firen, A. 1856. The seventeen-year locust, Cicada septem-
decim, Linnaeus. Pages 38-49 in First and second report
of the noxious, beneficial and other insects, of the state of
New-York. Albany.

Hamiton, D. W. 1962. Periodical cicadas, Magicicada spp.,
as pests in apple orchards. Indiana Academy of Science
Proceedings 71:116-121.

LeBaron, W. 1872. Periodical cicada. Pages 124-133 in
Second annual report on the noxious insects of the state
of Illinois. Springfield.

(33824—-3M—2-76 )

Lioyp, M., and H. S. Dysas. 1966a. The periodical cicada

problem. I. Population ecology. Evolution _20(2):
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, and . 1966b. The periodical cicada prob

lem. II. Evolution. Evolution 20(4) :466-505.

Marvatt, C. L. 1898. The periodical cicada, an account of
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of preventing its injury, together with a summary of
distribution of the different broods. U.S. Department
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series. 148 p.

ans

. 1907. The periodical cicada. U.S. Department
of Agriculture, Bureau of Entomology Bulletin 71. 181 p.

Moore, T. E., and R. D. ALEXANDER. 1958. The periodical
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national Congress of Entomology Proceedings, 1956.
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Mutter, H. J. 1957. Die Wirkung exogener Faktoren auf
die zyklische Formenbildung der Insekten, insbesondere
der Gattung Euscelis (Hom. Auchenorrhyncha). Zoolo-
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Ritey, C. V. 1868. “First account ever published of [a
13-year] brood” of the periodical cicada (exact title
not known). Journal of Agriculture, St. Louis, June
13, 1868. [This article, not seen, referred to by Riley
(1869:19) ].

. 1869. The periodical cicada. Pages 18—42 in First
annual report on the noxious, beneficial and other insects,
of the state of Missouri. Jefferson City.

1885. The periodical cicada. U.S. Department of
griculture, Division of Entomology Bulletin 8. Second
ed. 46 p.

Srannarp, L. J., Jr. 1965. Poiymorphism in the Putnam’s
seale, Aspidiotus ancylus (Homoptera: Coccoidea). En-
tomological Society of America Annals 58(4): 573-576.

Tuomas, C. 1865. Insects injurious to vegetation in Illinois.
Pages 401-468 in Illinois State Agricultural Society
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WatsH, B. D., and C. V. Ritey. 1868. The periodical cicada,
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