A plague of locusts: here comes Brood X

Other than damage to trees, the profusion of cicadas poses little harm to humans. Cicadas may cause alarm when they fly onto your shirt-sleeve, but they do not carry diseases, bite, or sting (except by accident).

Many people welcome the reappearance of periodical cicadas. For example, certain Native American tribes feast on the plump cicada nymphs as they emerge from the ground. Gene Kritsky, a renowned cicada biologist at the College of Mount St. Joseph in Cincinnati, Ohio, says the cicadas taste like canned asparagus. A few dozen stir-fried and served over rice make for a tasty treat.

Many people may have noticed that their yards are being churned by moles to an alarming extent. Mole populations are at an all-time high in many suburban areas where Brood X cicadas are abundant in the soil. With so many cicadas to cat, moles can raise larger families. But rest assured, the mole problem soon will solve itself. After Brood X emerges, mole populations will plummet. As far as moles are concerned, the new generation of cicadas simply are too small to eat and will not reach an edible size for at least 10 years.

The impending emergence may reflect a survival strategy that biologists call "predator satiation." There are so many cicadas that there are not enough predators to eat them all, thus leaving some adults (and their offspring) alive to reproduce again. It is not that predators do not try to devour them. Pretty much all of the local wildlife will drop what they are doing for a few weeks and gorge themselves on cicadas--even domestic animals such as cats and dogs.

With the aid of National Science Foundation grants, a group of Indiana University scientists hopes to determine whether cicadas have a significant impact on forests. The cicadas' enormous population sizes and their long-term parasitism on tree roots suggest that these curious creatures indeed might affect the way forests grow and change. The lower Midwest and southern Indiana in particular are at the epicenter of the Brood X emergence. Of course, there will be astonishing numbers of cicadas over a much larger region as well. Eastern forests are being threatened by a growing list of invading insect pests like the gypsy moth, emerald ash borer, and hemlock woolly adelgid. Could cicadas have an equally large, but more subtle, effect on forests?

A major goal of our research is to see what happens when Brood X cicadas' life cycle is disrupted by covering large swaths of young forest with netting, which will keep them at bay during the crucial period in which females normally would lay their eggs. We will compare netted, cicada-free areas with uncovered sections. This essentially is the start of a 17-year experiment, but we hope to have some results before 2021.

Although humans dominate the world in so many ways, some things are out of our control. A biological event of the magnitude of Brood X emphasizes that fact. We should be happy that cicadas are not killer bees or blood-sucking ticks. They simply are a benign (hopefully) part of nature--so sit back and enjoy the show.