Cicada Mania
Newspapers and other media around the US recently have been filled with discussions of an exceptional insect—cicadas. Broods or groups of some cicadas are called periodical cicadas. Their unique life cycles occur only in the Eastern United States in various geographic regions even though 3000 species of cicadas occur worldwide. Entomologists have determined that the US broods are composed of seven different species, morphologically similar but not identical. Each brood lives underground for exactly 13 years or exactly 17 years. When one or the other brood completes its life cycle, they break out of the ground to serenade citizens with a cacophonous din for a few weeks before depositing eggs on tiny tree twigs. After the eggs drop to the ground tiny nymphs at once begin their underground life, burrowing underground for either 13 or 17 years. It is clear this trait is genetically programmed in the insects, but scientists cannot explain how genetics produces their precisely timed behavior. How do these cicadas time their behavior so precisely?
This year two broods in Illinois are emerging at the same time. This event is termed a co-emergence. They have been named brood XIX, 13-year cicadas, and brood XIII, 17-year cicadas. Geographically brood XIX is found in southern Illinois and brood XIII is primarily located in northern Illinois. Entomologists predicted this year’s co-emergence for many years. The two specific broods geographically meet each other similar to pieces of a jigsaw puzzle, mostly in the state of Illinois. The 13 year and 17 year broods have not emerged in the same year in Illinois since 1803. This has generated considerable interest and excitement.
When my wife and I lived in Galena, IL, we experienced the din of Brood XIII cicadas in 2007. I recall many tiny dime-size holes in paths in our woods after they emerged from their underground lair after 17 years of subterranean feeding on sap from tree roots. Brood XIII cicadas are emerging once again in many Illinois localities in 2024. As we write, brood XIII is noisily emerging in eastern IL at the home of our daughter and her family. Dying 17 year insects and their spent exoskeletons are everywhere. These insects are members of brood XIII.
My personal experience with periodical cicadas reverts to 1962 when our family lived in New Jersey. Brood II, a 17-year species, was prevalent in New Jersey and several adjacent states. I recall transporting a group of young Sunday School students from their class picnic to experience the loud singing of cicadas in a nearby wooded area. In 1979, 17 years later, our 3-year old son was frightened when several cicadas alighted on him during a family outing at a nearby park. In 1996 Brad returned from college during the next appearance of Brood II. Together, we journeyed over to the same park to experience the loud singing of the same brood.
As a young person I also had experience with a different species of cicada called “dog day” cicadas, so-called because they emerged every summer during hot days known as “dog days.” These cicadas were similar in their structure but somewhat larger than periodical cicadas. They have greenish or olive colored bodies with large, black eyes. In contrast, periodical cicadas have delicate orange wing veins, dark bodies, and brilliant red eyes. Dog day cicadas do not create the loud noise of periodical cicadas. They sing individually instead of in a collective buzzing. Young and old alike may suffer from entomophobia until they subjectively perceive the physical beauty and behavioral uniqueness of these animals. They may even transition to entomophiles!
There are multiple reasons to exult in the natural world. The beauty and complexity of living things ranks at the top of the list. Periodical cicadas possess the longest known insect life cycle. Our God created countless fascinating characteristics of genetically programmed traits into living things, including the behavioral ability of periodical cicadas to discern time periods of 13 or 17 years.
