Seven Things Fruit Growers Should Know About Periodical Cicadas
Cicadas are in the national spotlight this year with the emergence of two groups (broods) of these insects in the eastern half of the country: Brood XIII (17-year) cicadas and Brood XIX (13-year) cicadas. Trillions of these insects will be emerging in 2024 from Wisconsin and Iowa all the way down to Georgia and the Carolinas. Here are seven key things that fruit growers and consultants should know about periodical cicadas.

The real “buzz” is about periodical cicadas: The Midwest is home to many different types of cicadas. The ones we see every year are commonly called “dog day cicadas”, since the adults are active during the hot “dog days” of summer. These have life cycles lasting 2-3 years, but due to overlapping generations, we see some adults every year. This year, all the hype is about the “periodical” cicadas, which have extended life cycles and periodical mass emergences. To help keep track of their activity, scientists sort these insects into numbered broods (cohorts) based on when they emerge; the broods are assigned Roman numerals. In southern Wisconsin and northern Illinois, we’ll see Brood XIII periodical cicadas, which have 17-year life cycles. These last made an appearance back in 2007, but our earliest published records for Wisconsin predate statehood!
How do periodical cicadas differ from our other cicadas? Compared to our common “dog day” cicadas, the periodicalcicadas look different and are active earlier in the year. Our dog-day cicadas are large (roughly 1 ¼ inch long), with a dark brownish or greenish color; the underside of the body is pale and the eyes are dark. The periodical cicadas tend to be slightly smaller and are colored differently—their bodies are blackish with orange on the wings and legs; the eyes are distinctly reddish. Periodical cicadas are active in late spring (May and June), while our “dog day” cicadas are active mostly in mid-and late summer.
Where will periodical cicadas emerge in Wisconsin? Periodical cicadas have a restricted distribution, and most Wisconsinites will not see these in their area. These cicadas only occur in localized spots in southern Wisconsin. Some key sites with known cicada activity include Arena, Beloit, Janesville, Mazomanie, Prairie du Chien, and Spring Green. The single best-known location for periodical cicadas in Wisconsin is the Lake Geneva area in Walworth County. Larger cities such as Milwaukee and Madison have not had any documented sightings in decades. Overall, there will be much more periodical cicada activity in northern Illinois compared to Wisconsin. To learn more about the distribution of periodical cicadas in Wisconsin, visit the Wisconsin Periodical Cicada website.
Will I have periodical cicadas in my particular area? The easiest way to know this is if you (or a neighbor) were in the same location during the last emergence in 2007. If you’re in the same spot and didn’t see them last time, you won’t be seeing them this year either. Periodical cicada populations in Wisconsin tend to be very localized and dispersal from those spots in minimal. Over time, land use changes can impact their populations. Since these insects are associated with trees, they have historically been known from forest and orchard settings. If previously wooded cicada habitat has been razed for other uses, those cicada populations will fizzle out in the absence of trees.
When will the periodical cicadas be active? 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 Brood XIII in 1990 and 2007, these cicadas typically become active in mid-to-late May in parts of Illinois. In Wisconsin, our cicada activity has mostly been in the month of June. With our above-average temperatures this spring, we might see mass activity beginning in the latter half of May. Once the adults emerge, they’ll be active for roughly a month.
Are periodical cicadas harmful? Periodical cicadas can’t sting or readily bite and they aren’t considered harmful to people or pets. They can be considered a minor nuisance due to their loud singing (80+ decibels), which could potentially interfere with outdoor gatherings. Looking at the bigger picture, the emergence can actually be quite beneficial to wildlife as these insects will serve as a readily available food source for a wide range of animals.
Cicadas can technically cause damage to fruit and landscape trees. After mating, adult females use a spear-like ovipositor (egg-laying structure) to slice into twigs and small branches. This injury can kill affected tissues and cause the associated leaves on to turn brown and wilt—a symptom known as “flagging”. For most trees, this damage tends to be minimal as a small percentage of the overall canopy is affected and no long-term harm occurs. However, damage could be more significant on recently-planted trees as a greater percentage of the canopy could be affected. Damage is typically managed by covering these plants with fine mesh netting to act as a physical barrier to keep cicadas at bay. Keep in mind that periodical cicadas can be very localized, so if you do not have a history of these insects, management is not needed.
Learn more and share your sightings: The recently launched Wisconsin Periodical Cicada website is a comprehensive source of information about these insects and is loaded with photographs, audio recordings, historical videos, and other resources. This website covers the biology and ecology of periodical cicadas and also dives deep into the known distribution of these insects in Wisconsin. Readers are also encouraged to share their periodical cicada sightings on the website to better document the distribution of these insects in Wisconsin.
The next emergence of Brood XIII cicadas in Wisconsin won’t occur until 2041. Take the time to appreciate these remarkable creatures as Wisconsinites only have a handful of opportunities in their entire lives to witness this phenomenon in the Badger State.
This article was posted in Insects and tagged Cicadas, insects, periodical cicadas, PJ Liesch.