Cicada Emergence Map
Find possible broods in a built-in state-level list and view up to 300 GBIF Magicicada observations. State membership does not prove a brood occurs at a specific location.
By Aryan Khan, Founder & Editor · Updated October 2026
A brood listed for a state may occur only in part of that state; verify local ranges with current specialist sources.
How to use Cicada Emergence Map
Underground for 13 or 17 years, then a few loud weeks. Whose ground are you on?
The tool uses a built-in state-level brood list and cycle arithmetic; it cannot determine whether a brood occurs at the selected location. The map shows up to 300 returned GBIF records, not a comprehensive range or forecast.
- 1Choose a US location.
- 2Review the possible state-level broods and cycle estimates.
- 3Check an authoritative local brood map before relying on the result.
What people use Cicada Emergence Map for
1. Planning around an emergence
A state-level list can be a starting point for research, but cannot tell whether an emergence will occur at a particular venue.
2. Gardeners and orchardists
Check current local extension or entomology guidance for tree protection and confirmed local brood ranges.
3. Curiosity and citizen science
GBIF observations and the state list can introduce the topic, but returned records are limited and not a complete survey.
4. Teaching prime-number biology
Cycle arithmetic helps illustrate 13- and 17-year periods; actual local emergence patterns require specialist sources.
Worked examples
Thirteen- and seventeen-year cycles have a least common multiple of 221 years. Local co-occurrence depends on actual ranges and is not established by this tool.
A 17-year cycle after 2021 gives 2038. The state list alone cannot establish that a specific location belongs to that brood.
Notable broods and their calendars
From published brood records (USDA Forest Service and university entomology) — last emergence plus period gives the next.
| Brood | Cycle | Last emerged | Next due |
|---|---|---|---|
| X (Great Eastern) | 17-year | 2021 | 2038 |
| XIII (Northern Illinois) | 17-year | 2024 | 2041 |
| XIV (Kentucky/Ohio-centred) | 17-year | 2025 | 2042 |
| XIX (Great Southern) | 13-year | 2024 | 2037 |
| II (East Coast) | 17-year | 2013 | 2030 |
The built-in list is a simplified state-level aid, not a mapped local boundary. Expected years are cycle arithmetic, not a guarantee of emergence.
How to interpret the result
The most common errors come from using a correct result to answer the wrong geographic question. Keep these points in mind for Cicada Emergence Map:
- Remember that elevation models see bare terrain: no buildings, no forest canopy. A line-of-sight 'clear' verdict can still be blocked by a wood, and a horizon distance assumes open ground — treat results as the terrain baseline, then add land cover from local knowledge.
- Include your height inputs explicitly (eye height, mast height, deck level) when sharing visibility results: the same hill answers differently for a child, an adult and a 10 m antenna, and unstated heights make numbers unreproducible.
Limits & appropriate use
Terrain intelligence carries one dominant limit: the model sees bare earth at ~90 m spacing with metres of vertical error, and is blind to canopies, walls and wires. Every downstream answer inherits it — profiles show terrain truth with noisy amplitude, line-of-sight verdicts are pending trees, horizons assume open ground, and solar radiation averages assume an unshaded panel. The second limit is temporal: climate letters and hardiness zones are thirty-year character, not this year's behaviour, and seismicity is a mood, not a hazard model. Each result here is printed with its recipe precisely so these boundaries travel with the number.
The value proposition is screening-grade truth at zero cost: orientation for sites, gardens, antennas, shoots and curiosity, with the upgrade points clearly marked. When money or safety attaches to the answer — tower siting, flood insurance, structural shading, avalanche terrain — the escalation is professional: licensed survey, certified shade studies, regulatory flood determinations and geological hazard services. A good free tool makes that ladder visible instead of pretending to be the top of it.
- Construction and tower siting → licensed topographic survey.
- Flood decisions → regulatory determinations (FEMA/FIRM in the US).
- Solar finance → certified shade and production studies.
Data & methodology
A built-in state-level brood list and 13- or 17-year cycle arithmetic; up to 300 GBIF occurrence records are plotted without a completeness guarantee.
For source details, licences and model limitations, see Data Sources and Methodology.
Key terms worth knowing
- Antipode
- The diametrically opposite point; latitude flips, longitude shifts 180°.
- Köppen class
- The letter-code climate system from temperature/precipitation thresholds.
Editorial guidance: MapBench explains the method and limitations so the tool can be used as a transparent reference, not as a black-box answer. For legal boundaries, safety-critical routing, surveying, engineering, regulated decisions or official statistics, verify the result with the responsible authority or a qualified professional.
Category: Earth Science. Results are intended for everyday analysis and planning unless a page explicitly states otherwise.
Method, assumptions & limits
- This tool’s method
- A built-in state-level brood list and 13- or 17-year cycle arithmetic; up to 300 GBIF occurrence records are plotted without a completeness guarantee.
- Before relying on the answer
- Check the location, height units and any model options shown by this calculator. A terrain lookup and a geometric Earth model answer different questions.
- What the result cannot establish
- Local terrain, atmospheric conditions and source resolution can matter more than numerical rounding. Do not use a planning result for safety-critical work.
Coverage: US focused. Search, basemap and external data requests may use third-party services; browser-based does not mean every operation is offline. Read the source and licence notes, calculation methodology and privacy policy. If a result looks inconsistent, report a correction with the inputs and mode used.
Frequently asked questions
Clear answers about the calculation, accuracy and appropriate use.
Does it identify the brood at my address?
No. The list matches a geocoded state only; check current specialist brood maps for local ranges.
Are map dots a forecast?
No. They are a limited set of GBIF observations, not a full range or forecast.
Is this suitable for engineering or legal decisions?
Treat the result as planning or educational context unless the page explicitly says otherwise. Engineering, hazard and legal decisions should use authoritative specialist data.
Why can terrain data differ between sources?
Elevation and earth datasets vary in resolution, collection date and processing method. Small local features may not be represented equally.
Can I verify the data source?
Yes. MapBench documents major providers and methodology on the Data Sources and Methodology pages.
What triggers the exact week?
Soil temperature — nymphs emerge when soil at about 20 cm depth reaches roughly 18°C (64°F), usually after rain. The year is the brood's clockwork; the week is spring's.
How many broods are there?
Fifteen recognised broods in the eastern US: twelve on 17-year cycles and three on 13-year cycles, numbered I–XXX with gaps where broods have gone extinct or were never assigned.
Are periodical cicadas locusts?
No — locusts are grasshoppers. 'Seventeen-year locust' is a settler-era misnomer stuck to a true cicada (genus Magicicada), harmless to people and pets.
Do they damage trees fatally?
Egg-laying slits flag small branches ('flagging') and can set back young or stressed trees; established trees shrug it off. The underground years of root feeding are gentle. Netting protects saplings in emergence springs.
Annual 'dog-day' cicadas instead?
Those appear every summer in small numbers and are not broods — this map covers periodical Magicicada only; a lone August singer is a different insect entirely.
My county borders two broods.
The tool does not identify county-level ranges. Consult a current specialist brood map for local detail.
Related tools and resources
Garden companion: the Plant Hardiness Zone; climate context: the Climate Zone Finder; the latitude frame: the Distance from Equator Calculator.
More free tools
Sources, methodology & editorial trust
- ✓ Browser-first processing where supported
- ✓ External sources are documented
- ✓ No account required for public tools
- ✓ Review data sources
Calculations are documented with their assumptions, limitations and source context rather than presented as unexplained answers.
Reviewed and maintained by Aryan Khan, Founder & Editor of MapBench.
Part of our elevation & terrain hub
Cicada Emergence Map sits in the elevation & terrain cluster, alongside 40 other tools that answer neighbouring questions with different methods or datasets.
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