Mapping Brood X Periodical Cicadas in Kentucky

What is happening with cicadas in 2021?

2021 will feature the emergence of Brood X, one of the groups of periodical cicadas that lives in Kentucky. Brood X is a 17-year brood, meaning that the insects that will be aboveground as adults this year were born in 2004 and have been developing in the soil ever since. The below ground nymphs have been siphoning off sap from their host trees and now that they are surly teenagers, they are ready to become adults. The adult cicadas should begin to appear around the beginning of May, more specifically when the soil 8 inches belowground reaches 64°F, which often coincides with the blooming of outdoor irises.

Where will this happen?

If you have been in Kentucky for a while, you have probably experienced periodical cicada emergences before. The history of these cicadas in the state has been chronicled by researchers in the past and you can see some of the maps generated by them in the extension publication, ENT-52. If you look at those maps you will notice that Broods X (10), XIV (14), and XXIII (23) are the ones with the widest historical distribution in the state.

However, when we look at sources, such as Cicada Mania and the University of Connecticut, we will notice that the expected areas with the most cicadas in Kentucky is considerably smaller than the historical maps might indicate. According to these sources, the counties that should expect to see the most cicadas are Boone, Breckenridge, Bullitt, Carroll, Daviess, Gallatin, Grayson, Henry, Jefferson, La Rue, McLean, Muhlenberg, Nelson, Ohio, Oldham, Trimble.

Figure 1: The counties that should expect to see the most cicadas in 2021 are found mostly in northern Kentucky, near river corridors.

That does not mean that there won’t be cicadas in any other counties, and in fact, we have a lot of interest in knowing exactly where people are seeing them in the state. We would appreciate it if folks who spot a periodical cicada in Kentucky could report that sighting as part of a citizen science effort to map these critters in our state. There are multiple avenues to do this, including using Cicada Safari, a mapping app you can download on your phone. Users can take a photo or video of the cicadas they see and upload it to a database where they will note the location of the cicadas and confirm their species identification. This will help with a national effort, as well as the Kentucky effort, to better map the periodical cicadas and improve understanding of their emergences. This is technology we didn’t get to use the last time Brood X was aboveground, and we hope that Kentuckians will use it. Alternatively, people can also take a picture and note the location of their find in an email message to the Office of the State Entomologist or to Kentucky Bugs on Facebook

Figure 2: How can you help with periodical cicada citizen science? By going outdoors and looking for cicadas this May and June and taking pictures of them; upload those pictures to Cicada Safari or send them to one of our Extension entomology resources.


Jonathan L. Larson, Entomology Extension Specialist

Posted in Landscapes
%d bloggers like this: