Cicadas

The emergence of cicadas has already begun in the Chicago area and parts of Illinois, signaling the start of their fascinating life cycle. While it’s earlier than usual for Illinois, the full-blown swarms and the unmistakable buzzing sounds that accompany them are yet to reach their peak.

According to experts from the Insect Asylum, the anticipated peak emergence is forecasted for mid-May in the Chicago region. Although sightings have been reported sporadically, several factors will influence when cicadas will emerge in large numbers.

Traditionally, cicadas surface as the ground warms up during the spring and early summer months, typically from mid-to-late May into June. Stephanie Adams, a plant pathologist at Morton Arboretum in Lisle, mentioned that Brood XIII, the current group of cicadas, has been emerging over the past week and a half. Their presence has been noted in various locations, including landscapes and wooded areas.

Adams pointed out that the initial emergence is about two weeks earlier than the historical average. However, the process will likely remain irregular due to factors like soil temperature, mulch, and turf grass, which affect cicadas differently. For instance, areas near pavement tend to have warmer soil, prompting cicadas to emerge more rapidly.

As the cicada phenomenon unfolds, residents can expect to witness the fascinating spectacle of these insects emerging from the ground and filling the air with their distinctive calls.

According to reports from the Insect Asylum, the ideal soil temperature for cicadas to emerge is around 64 degrees Fahrenheit. However, an increase in humidity levels can also influence their emergence.

Cicadas typically have a relatively short lifespan of approximately four weeks. This means that the emergence is expected to continue at least until mid-June, offering ample time for these fascinating insects to complete their life cycle.

As noted by the National Weather Service, research indicates that the timing of the periodical cicadas’ emergence is closely tied to soil temperature. Cicada nymphs emerge from the ground following a rainstorm, particularly when the soil temperature at a depth of 8 inches exceeds approximately 64°F. This synchronization between rainfall and soil temperature triggers the emergence of cicadas, marking the beginning of their above-ground phase.

In 2024, two broods of cicadas are emerging: Brood XIII and Brood XIX. This occurrence is noteworthy as these two broods haven’t emerged simultaneously in 221 years.

For the Chicago area, Brood XIII is expected to be predominantly seen in parts of northern Illinois and Indiana, with potential sightings extending to Wisconsin and Ohio, according to Dr. Gene Kritsky, the dean of Behavioral and Natural Sciences at Mount St. Joseph University in Cincinnati.

Brood XIII, specifically the Northern Illinois Brood, is renowned for its extensive emergence, earning a reputation as the “largest emergence of cicadas anywhere,” as noted by the University of Illinois. In 1956, entomologists documented as many as 311 “emergence holes” per square yard in a forested floodplain near Chicago, indicating a density of 1.5 million cicadas per acre.

The aftermath of the cicadas’ emergence can also be notable, with large numbers of deceased cicadas accumulating on the ground and emitting a noticeable odor from their decomposing bodies. In some instances, residents have had to use snow shovels to clear their sidewalks of the deceased cicadas.

On the other hand, Brood XIX, also known as the Great Southern Brood cicadas, has a broader distribution, spanning parts of Missouri, Illinois, Louisiana, North Carolina, Virginia, and Maryland. This brood is recognized for its extensive geographic extent, reaching from the Midwest to the East Coast.

Despite the primarily southern distribution of 13-year cicadas, Brood XIX has been recorded as far north as Chebanse, IL, approximately 75 miles from Chicago’s Loop, showcasing the remarkable reach of this brood.

In Illinois, cicadas are expected to emerge across most regions, including the Chicago area. Moreover, there is a unique occurrence anticipated in a narrow part of the state where both Brood XIII and Brood XIX could emerge simultaneously, in the same location.

Catherine Dana, a cicada expert affiliated with the Illinois Natural History Survey, highlighted the significance of this year for Illinois, noting that cicadas will likely emerge extensively throughout the state.

According to data from the USDA Forest Service, here’s a summary of what to expect in Illinois:

– Brood XIII is expected to emerge predominantly in parts of northern Illinois and Indiana, with potential sightings extending to Wisconsin and Ohio.
– Brood XIX, known as the Great Southern Brood cicadas, is projected to have a broader distribution, spanning various regions of the state, including Missouri, Illinois, Louisiana, North Carolina, Virginia, and Maryland.

This comprehensive emergence of cicadas across Illinois promises to provide a unique and memorable experience for residents and visitors alike.

“Somewhere around Central Illinois, probably around Springfield, is where some researchers are predicting we may see some overlap of these two different broods,” Dana said. “It’s not going to be a large area, but there will likely be some mating happening between these two broods, which is going to be really exciting.”