Brood X

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Brood X cicada

Brood X (Brood 10), the Great Eastern Brood, is one of 15 broods of periodical cicadas that appear regularly throughout the eastern United States. It has the greatest range and concentration of any of the 17-year cicadas.

Every 17 years, Brood X cicadas tunnel en masse to the surface of the ground, lay eggs, and then die off in several weeks. The combination of long dormancy, simultaneous emergence of vast numbers, and short period before the nymphs' burrowing underground to safety, allows the brood to survive even massive predation.[1]

A 17 year Cicada from brood X 2004 - Princeton, NJ
2004 Brood X swarm in Ohio
Detail of swarm
Emergence holes located under flagstone

Pehr Kalm, a Swedish naturalist visiting Pennsylvania and New Jersey in 1749 on behalf of his nation's government, observed in late May an emergence of Brood X.[2] When reporting the event in a paper that a Swedish academic journal published in 1756, Kalm wrote:

The general opinion is that these insects appear in these fantastic numbers in every seventeenth year. Meanwhile, except for an occasional one which may appear in the summer, they remain underground.
There is considerable evidence that these insects appear every seventeenth year in Pennsylvania.[2]

Kalm then described documents (including one that he had obtained from Benjamin Franklin) that had recorded in Pennsylvania the emergence from the ground of large numbers of cicadas during May 1715 and May 1732. He noted that the people who had prepared these documents had made no such reports in other years.[2] Kalm further noted that others had informed him that they had seen cicadas only occasionally before the insects appeared in large swarms during 1749.[2] He additionally stated that he had not heard any cicadas in Pennsylvania and New Jersey in 1750 in the same months and areas in which he had heard many in 1749.[2] The 1715 and 1732 reports, when coupled with his own 1749 and 1750 observations, supported the previous "general opinion" that he had cited.

Kalm summarized his observations and conclusions in a paper translated into English in 1771, in which he cited his 1756 Swedish publication[3] and stated:

There are a kind of locusts which about every seventeen years come hither in incredible numbers .... In the interval between the years when they are numerous, they are only seen or heard single in the woods.[3][4]

In April 1800, Benjamin Banneker, who lived near Ellicott's Mills, Maryland, documented three Brood X emergences when writing in in his record book that he recalled a "great locust year" in 1749, a second in 1766 during which the insects appeared to be "full as numerous as the first" and a third in 1783. He predicted that the insects "may be expected again in the year 1800, which is seventeen years since their third appearance to me".[5]

Brood X's most recent appearance was in the spring and early summer of 2004 throughout an area roughly enclosed by Illinois, Michigan, New York and Georgia. The next appearances will be in 2021 and 2038.[1][6]

Bob Dylan's song "Day of the Locusts" (on his 1970 album New Morning) refers to the Brood X cicadas that were present in Princeton, New Jersey in June 1970 when Dylan received an honorary degree from Princeton University.[7][8][9][10]


  1. ^ a b Post, Susan L.; Michael R. Jeffords (photos) (Summer 2004). "A Trill of a Lifetime: More Information About the Periodical Cicada". Illinois Natural History Survey. Prairie Research Institute. Retrieved 2011-07-01. 
  2. ^ a b c d e Davis, J.J. (May 1953). "Pehr Kalm's Description of the Periodical Cicada, Magicicada septendecim L., from Kongl. Svenska Vetenskap Academiens Handlinger, 17:101-116, 1756, translated by Larson, Esther Louise (Mrs. K.E. Doak)". The Ohio Journal of Science 53: 139–140. Archived from the original (PDF) on 2012-10-02.  Republished by Knowledge Bank: The Ohio State University Libraries and Office of the Chief Information Officer. Retrieved 2012-10-02.
  3. ^ a b Kalm, Peter (1771). Travels into North America: Translated into English, By John Reinhold Foster 2. London: T. Lowndess. pp. 212–213.  At Google Books.
  4. ^ Marlatt, C.L. (1898). "The Periodical Cicada in Literature". The Periodical Cicada: An Account of Cicada Septendecim, Its Natural Enemies and the Means of Preventing its Injury, Together With A Summary of the Distribution of the Different Broods (Bulletin No. 14 - New Series, U.S. Department of Agriculture, Division of Entomology). Washington, D.C.: United States Government Printing Office. pp. 112–118.  At Google Books.
  5. ^ Latrobe, John H. B., Esq. (1845). Memoir of Benjamin Banneker: Read before the Maryland Historical Society at the Monthly Meeting, May 1, 1845. Baltimore, Maryland: Printed by John D. Toy. pp. 11–12. OCLC 568468091. Retrieved 2015-10-07.  At Google Books
  6. ^ Moore, Thomas E.; Thomas J. Walker (April 27, 2001). "Genus Magicicada periodical cicadas". Singing Insects of North America. University of Florida Institute of Food and Agricultural Sciences. Archived from the original on 2008-09-30. Retrieved 2011-07-01. 
  7. ^ James Barron (1996-06-04). "Cicadas: They're Back!". The New York Times. Retrieved 2013-04-08. 
  8. ^ "Are Periodical Cicadas Coming to Your Town - Magicicada Broods and Brood Maps". Retrieved 2013-04-08. 
  9. ^ "Bob Dylan Receives Honorary Princeton Degree | Music News". Rolling Stone. 1970-07-09. Retrieved 2013-04-08. 
  10. ^ Cameron W. Barr. "In D.C. Area. It's the Day Of the Cicada". The Washington Post. page A1. March 28, 2004. retrieved January 25, 2015.

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