[11] Pehr Kalm, a Finnish naturalist visiting Pennsylvania and New Jersey in 1749 on behalf of the Royal Swedish Academy of Sciences, observed in late May another emergence of that brood.

[12][13] 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.

Sandel's report and one that he had obtained from Benjamin Franklin that had recorded in Philadelphia the emergence from the ground of large numbers of cicadas during early May 1732.

Kalm summarized his findings in a book translated into English and published in London in 1771,[14] stating: There are a kind of Locusts which about every seventeen years come hither in incredible numbers ...

Bartram noted that upon hatching from eggs deposited in the twigs of trees, the young insects ran down to the earth and "entered the first opening that they could find".

[18] In April 1800, Benjamin Banneker, who lived near Ellicott's Mills, Maryland, wrote 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 (Brood X).