Cicadas are here! Why are American researchers eager to study them!?

Two specific broods of insects appear together for the first time in two centuries, and we don't know much about them.

The appearance is in full swing. Periodic cicadas (Magicicada) crawl out of the ground in huge numbers - perhaps in trillions - in the southeast and midwest of the United States. And researchers, many of whom usually study other insects, drop everything and run to the places where they appeared, trying to collect samples and observe the environmental spectacle.

We don't know a lot about these insects, which spend most of their lives at a depth of about 60 centimeters underground, "in a small hole in the mud," says Martha Weiss, an entomologist at Georgetown University in Washington, DC.

The appearance this year also increases the rates for researchers. Two specific broods - groups of several species of cicadas with the same life cycle, which appeared above the ground in the same year - are synchronized for the first time in 221 years. This means that the last time they saw daylight together was when the third president Thomas Jefferson led the United States. Brood XIX, also known as Big Southern Brood, appeared within the last few weeks after 13 years underground, and the northerner brood XIII only began to appear after 17 years.

Geographically, these two broods do not intersect much, although "they are very close to each other" in central Illinois, near the city of Springfield, says Chris Simon, evolutionary biologist and entomologist at the University of Connecticut at Storrs. The XIX brood covers the largest area of all known cicad broods: from Maryland to Georgia in the southeast and from Iowa to Oklahoma in the Midwest. Meanwhile, Brood XIII covers northern Illinois, including Chicago.

But a possible contact zone exists, and some scientists flock there. Katie Dana, an entomologist associated with the study of the natural history of Illinois at the University of Illinois Urbana-Champaign, hopes to find out how these two broods can interact and how their marriage songs differ. Usually, the height of these songs is one of the ways to distinguish many visually similar species of cicadas.

It could also be a way to distinguish between broods XIX and XIII. According to experts, they are also closely related and look the same, which makes crossing possible, but very difficult to study in this area.