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.
Where will Brood XIV emerge?
Why stragglers are an issue for Brood XIV.
A perennial issue with Brood XIV is that it occurs 8 years after Brood VI, 4 years after Brood X, and four years before Brood I. These broods are adjacent to each other in parts of their ranges. From a biological perspective, stragglers from any of these broods are of interest because they can cause gene flow among these broods. From a practical perspective, stragglers from any of these broods complicate mapping efforts, because populations may be difficult to assign to a brood. Some straggling emergences are easily identified as such, since they involve only small numbers of cicadas. Others are less easily interpreted, and the difficulty may be compounded by the problem of “shadow brooding” in which repeated instances of straggling resupply populations of stragglers that are on the verge of becoming self-sustaining. This map allows you to explore how straggling will complicate the interpretation of emergences in 2025.
An overriding philosophy of the mapping project is: A Misleading Map is Worse Than No Map At All. There will be substantial numbers of stragglers in 2025, and if they are mistaken for Brood XIV emergences, these mistaken records will create the impression that Brood XIV has grown suddenly and substantially larger, when no such thing is true. When we collect mapping records, we keep track of densities– in all likelihood, true Brood XIV emergences will be dense and widespread, while straggler emergences tend to be more patchy and scattered (More details about how we take records are what we use for mapping criteria are found here.).
Key points about stragglers:
- Stragglers typically occur at low densities
- Stragglers are typically patchy
- Stragglers populations generally don’t last for long!
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.
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. How dense are they? See the discussion on this page.
Are cicadas affected by climate change?
Yes… but they always have been. It’s complicated…
To learn more about periodical cicadas, explore our website!
More information about broods adjacent to Brood XIV can be found here.