I CAN’T WAIT FOR THEM to announce themselves noisily, though readers have been writing in, expressing varying degrees of cicada anxiety. Brood II of the periodical 17-year cicadas—the brood that returns on that uncanny schedule specifically to parts of the East, from Georgia to Connecticut, are already being sighted where soil temperatures have warmed to the preferred 64 degrees. As with all things, I’m most fascinated by these insects’ role in the bigger ecological picture—besides the sheer magical aspect of witnessing their incredible orgy. Some cicada facts I’ve learned:
intriguing periodical cicada facts
- There are other cicadas that appear annually–sometimes called dog-day cicadas—found around the world, but the periodic types, appearing every 13 or 17 years, only occur in North America. (The periodicals are genus Magicicada; the dog-day types are genus Tibicen.)
- Though sometimes referred to as the 17- or 13-year locusts, periodical cicadas are not locusts (which are a kind of grasshopper).
- The periodical types were first noted in scientific literature in 1665, under the heading, “Some Observations of Strange Insects, and the Mischiefs done by them.”
- Today, each cyclical population of periodic cicadas is called a brood, and there are a total of 15 broods. A chart of all the broods and locations is here. (Other broods in other regions than the East’s Brood II are on a different timetable.)
- Cicadas don’t bite or sting. (And if you have a dog, don’t worry if he/she chases them and eats them.)
- On the ecological scale, they seem to do more good than harm. Though some “flagging,” or browning and dieback may occur on young twigs that the females prefer to deposit their eggs into, and some root and other tissue feeding on plants may occur, the cicadas also leave behind much goodness:
- “The mass emergence can benefit the longer, overall health of eastern forests,” says U.S. Forest Service Michael Boehne on the UDSA website. “After mating and laying eggs, adult cicadas die and fall to the forest floor. The nutrients released from the mass decay of the brood create a jolt of healthy nutrients available to forest organisms. Researchers have shown that this pulse of nutrition leads to an increase of beneficial microbes and nitrogen in soil, increased tree growth and more robust wildflowers.”
- Young trees—ones four years or younger, such as in a young orchard, most references say, meaning whose wood is within the preferred range for egg-laying–could be covered in defense if you are in an area where population densities are high.
- Periodical cicadas are a foodstuff for various birds (including catbirds and bluejays, to name two familiar species). One recent research theory says they may outsmart predator birds with their uncanny timing—that perhaps their 13- or 17-year timing coincides with population dips in bird species that favor them as food, or even influences the dips. Wild! Read about that theory in “Scientific American.”
- You can help track the emergence of Brood II (which occurs when soil temperatures reach 64 degrees F) as part of a citizen-science project being undertaken by the public-radio program Radiolab. Me, I’m hoping to have the privilege of seeing them—though there’s no guarantee in any given spot that you will, even in an emergence year.
articles i enjoyed on periodical cicadas
- A recent overview from the USDA Forest Service website
- More about their role in the overall ecology, from Vanderbilt University
- They’ve already been seen in the Washington area; “The Washington Post” reported first sightings in a May 13 article
- The Magicicada.org website