The 2025 Periodical Cicada Emergence

In 2025, Brood XIV, which among the largest of all 17-year periodical cicada broods, will emerge.

To learn more about periodical cicadas, explore our website!

The most recent scientific review of periodical cicada biology (Simon et al. 2022) may be found here.

The most recent updates and news posts may be found here.

Brood XIV is a “Keystone” Brood

The Lloyd and Dybas (1966) “Four-Year Acceleration” sheme showed how all other 17-year broods could be derived from Brood XIV by repeated instances of “acceleration” or emergence 1- or 4-years ahead of schedule.  the “Four Year Jump” hypothesis (Cooley et al. 2018) allows “accelerations” and “decelerations,” removing the constraint that life cycle changes must involve emergences ahead of schedule by allowing emergences behind schedule as well.  Despite this change, Brood XIV is still at the center of this hypothesis.

Four Year jump Model from Cooley et al. 2018
The four-year jump model for deriving all 17-year periodical cicada broods from a postulated Brood XIV ancestor, by a combination of 4-year and 1-year accelerations. Broods for which there are no or doubtful historical records are excluded. Double-headed arrows have been added to show both accelerations and decelerations. Triple arrows indicate the possibility of continuous migration through time between geographically overlapping populations over generations. Black arrows indicate jumps that are hypothesized to occur with high probability, grey arrows indicate jumps that are hypothesized to be rare or that do not occur today but may have occurred in the past. Dashed arrows indicate doubtful processes due to lack of geographic proximity. Broods in parentheses are probably not self-perpetuating at present but may have been in the past. Broods in square brackets are extinct. Under this scheme, one-year decelerations not required and are not shown.

Refining hypotheses for 17-year periodical cicada brood evolution requires accurate maps.

  • Brood XIV has disunct populations on Long Island and Cape Cod (Simon and Lloyd 1982); the Long Island populations of all broods seem to be declining.  Tracking these populations in 2025 is important for determining whether they are in danger of becoming extinct.
  • More information is needed about the distribution of Brood XIV in southwestern Ohio and southeastern Indiana in order to place into context the apparently shifting distributions of  Broods VI, X, and XIV in this region (Kritsky 1987, 1988, 1992; Kritsky et al. 2005).
  • More information is needed about the distribution of Brood XIV in northeastern Tennessee and southwestern Virginia, to understand how it interacts with a newly identified disjunct population of Brood I (Cooley 2015).
  • More information is needed about the distribution of Brood XIV in northern Kentucky to understand how it interacts with a newly identified disjunct population of Brood XXII (Kritsky et al. 2017).

In 2025, we will map Brood XIV to address these gaps in our knowledge.

How many cicadas will there be?

Although there are a lot of periodical cicadas, they are not generally considered to be insect pests and there is no reason to use pesticides on them. Instead, see our FAQ for other means of management.

It turns out that it is extremely hard to estimate the population sizes of periodical cicadas, for any number of reasons. The oft-quoted figure of densities that can exceed a million per acre comes from a census taken during the 1956 emergence of Brood XIII in Raccoon Grove, IL (Dybas and Davis 1962).

If we accept a rough estimate of one million cicadas per acre… should that be surprising? How many ants are there per acre? How many mayflies? How many fruit flies? Insects often come in large numbers. What’s special about Magicicada is not the large numbers per se, but the periodicity– the predictable, synchronous emergence of large numbers of adults and their near-total absence in the years between (see the “straggler” page for more information).

The state of Delaware is roughly 1.5 million acres in size. If we accept an estimate of a million cicadas per acre and if the total combined area of a periodical cicada emergence is roughly the size of Delaware, then more than a trillion will be present– but not all in the same place at the same time.

Are cicadas affected by climate change?

Yes… but they always have been. It’s complicated…


To learn more about periodical cicadas, explore our website!


Literature