When & Where

When?

This question has a fairly straightforward answer, although weather patterns can influence the emergence date. A big factor for periodical cicada emergence is the temperature of the soil. Scientists have found that periodical cicadas emerge when soil temperature at a depth of 8 inches exceeds 64˚F (18˚C). Based on records from the Brood XIII activity in 1990 and 2007, these cicadas have typically become active in mid-to-late May in parts of Illinois. In Wisconsin, emergence often begins in late May with most activity occurring in the month of June. For 2024, start paying close attention to possible sightings and reports in mid-May.  Since the adults are short-lived, activity of periodical cicadas will likely start to taper off in late June and will cease in July.

Keep in mind that El Niño, climate change, and spring weather patterns could potentially shift things earlier this year.  Some websites provide interactive soil temperature maps, such as this one from the Wisconsin Environmental Mesonet  (Wisconet) network of weather monitoring stations (select 8″ soil depth from the pull down menu at the top of the map).  At home, a long grilling thermometer can also be used to check soil temperatures in your own yard.

Where?

Broadly-speaking, Wisconsin’s periodical cicadas are restricted to the southern part of the state. Historical maps show cicadas distributed across roughly the southern two rows of counties in Wisconsin and making it as far north as Sauk County.  However, early published records were somewhat limited in their value due to their poor resolution (often county-level, rather than specific locations) and erroneous reports.  There are also more recent reports from additional counties (i.e., Racine and Kenosha) that were not included in some of the key historical maps.

While we generally know where periodical cicadas occur in the state, answering this question at a more local level is much harder.  Our Brood XIII periodical cicadas occur in geographically isolated pockets where they’ve historically occurred. When it comes to their distribution, think of it more like pushpins on the map rather than entire counties. With that said, most residents of Wisconsin—even southern Wisconsin—will not have periodical cicadas in their own yards or neighborhoods.

To better document the distribution of periodical cicadas in Wisconsin, a thorough literature search was conducted in early 2024.  This information was used to create a map and summary table (below).  Records were obtained from the UW Insect Diagnostic Lab, specimens from the Wisconsin Insect Research Collection, state government reports (Department of Agriculture, Department of Natural Resources, Extension Reports), historical publications on periodical cicadas, more recent scientific literature, 150+ years of newspaper articles, and participatory science websites such as Bugguide.net and iNaturalist.

Hotspots & Viewing Tips

Of all the locations in Wisconsin, the Lake Geneva area will be the most reliable place to view periodical cicadas due to their well-established record there—especially along the northern side of the lake. A number of parks and nature preserves in the Lake Geneva area afford plenty of opportunities to experience these insects. Other “hotspots” include the Janesville area (Rock River Heritage County Park), Beloit, Prairie du Chien, and the general Spring Green area (hint: try some side roads near between Spring Green and Governor Dodge State Park—you just might stumble upon an undocumented population). When visiting spots on the map (or exploring other locations), your ear may be the best tool to cue you in on the presence of cicadas.

Keep in mind that the range of our Brood XIII periodical cicadas may be shrinking over time as cicada habitat is lost due to land-use changes and development. Thus, spots that previously had cicadas might not have them if significant land use changes have occurred.

The table below highlights important details for each county shaded in on the map and provides additional information on where to go looking for these insects.