[4] In the spring of their 13th or 17th year, mature cicada nymphs emerge between late April and early June (depending on latitude), synchronously and in tremendous numbers.

Existing young trees or shrubs can be covered with cheesecloth or other mesh netting with holes that are 3⁄8 in (1.0 cm) in diameter or smaller to prevent damage during the oviposition period,[15] which begins about a week after the first adults emerge and lasts until all females have died.

[citation needed] The nymphs of the periodical cicadas live underground, usually within 2 ft (61 cm) of the surface, feeding on the juices of plant roots.

[18] In late April to early June of the emergence year, mature fifth-instar nymphs construct tunnels to the surface and wait for the soil temperature to reach a critical value.

Emerging nymphs may molt in the grass or climb from a few centimeters to more than 100 feet (30 m) to find a suitable vertical surface to complete their transformation into adults.

Singing males of the same Magicicada species tend to form aggregations called choruses whose collective songs are attractive to females.

The details of this strategy are simple: for the first week after emergence the periodical cicadas are easy prey for reptiles, birds, squirrels, cats, dogs and other small and large mammals.

In this way prime-numbered broods exhibit a strategy to ensure that they nearly always emerge when some portion of the predators they will confront are sexually immature and therefore incapable of taking maximum advantage of the momentarily limitless food supply.

[30] Wild turkey populations respond favorably to increased nutrition in their food supply from gorging on cicada adults on the ground at the end of their life cycles.

Eastern gray squirrel populations have been negatively affected, because the egg-laying activity of female cicadas damaged upcoming mast crops.

However, the two broods were not expected to overlap except potentially in a thin area in central and eastern Illinois (Macon, Sangamon, Livingston, and Logan counties).

The 17-year cicadas largely occupy formerly glaciated territory, and as a result their phylogeographic relationships reflect the effects of repeated contraction into glacial refugia (small islands of suitable habitat) and subsequent re-expansion during multiple interglacial periods.

In each species group, Decim, Cassini, and Decula, the signature of the glacial periods is manifested in three phylogeographic genetic subdivisions: one subgroup east of the Appalachians, one midwestern, and one on the far western edge of their range.

An effort sponsored by the National Geographic Society is underway as of April 2021 at the University of Connecticut to generate new distribution maps of all periodical cicada broods.

[60] After cicada emergences have ended, many people have therefore developed rashes, pustules, intense itching and other mite bite sequelae on their upper torso, head, neck and arms.

The first known account of a large emergence of cicadas appeared in a 1633 report by William Bradford, the governor of the Plymouth Colony, which had been established in 1620 within the future state of Massachusetts.

[64][65] After describing a "pestilent fever" that had swept through the colony and neighboring Indians, the report stated: It is to be observed that, the spring before this sickness, there was a numerous company of Flies which were like for bigness unto wasps or Bumble-Bees; they came out of little holes in the ground, and did eat up the green things, and made such a constant yelling noise as made the woods ring of them, and ready to deafen the hearers; they were not any seen or heard by the English in this country before this time; but the Indians told them that sickness would follow, and so it did, very hot, in the months of June, July, and August of that summer.

[67][70] John Bartram, a noted Philadelphia botanist and horticulturist, was among the early writers that described the insect's life cycle, appearance and characteristics.

[72] 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.

[73][74] 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.

[74]Kalm then described 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,[75] stating: There are a kind of Locusts which about every seventeen years come hither in incredible numbers ...

Bartram's article, which a London journal published in 1768, 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".

The sudden arrival of such a substantial quantity of the cicadas provided a source of sustenance for the Onondaga people who were experiencing severe food insecurity following the Sullivan campaigns and the subsequent brutal winter.

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.

[82] Describing an effect that the pathogenic fungus, Massospora cicadina, has on its host,[83] Banneker's record book stated that the insects:... begin to Sing or make a noise from first they come out of the Earth till they die.

[32] Ten years later, the American Entomologist published in December 1868 a paper that Benjamin Dann Walsh and Charles Valentine Riley had written that also reported the 13-year periodicity of the southern cicada broods.

[32] Walsh's and Riley's paper, which Scientific American reprinted in January 1869, illustrated the interior and exterior characteristics of the nymphs' emergence holes and raised turrets.

While investigating with the help of others the mysterious itchy welts and rashes that people were developing in Chicago's suburbs after the end of a 2007 Brood XIII emergence, he attributed the event to bites by mites whose populations had quickly increased while parasitizing those eggs.

[93][94] Marlatt wrote in 1907: The use of the newly emerged and succulent cicadas as an article of human diet has merely a theoretical interest, because, if for no other reason, they occur too rarely to have any real value.