News

Natural Highlights: Periodical Cicadas

Big, noisy insects with bright red eyes, orange-veined wings, and black bodies, periodical cicadas are hard to ignore. They are also completely harmless to people.  There are seven different species of periodical cicadas, all in the genus Magicicada.  Some species emerge every 17 years, but the four species which occur in the Midsouth are 13-year cicadas.  They spend most of their lives underground feeding on the fluids of tree roots, then emerge en masse to find a mate, feed on twigs, and reproduce. After about four weeks, it's all over.  The cicadas die and we'll have to wait another 13 years for their progeny to emerge.  There will be plenty of noisy non-periodical annual cicadas around, however, to add to the summer soundscape.

   photo by C. Justis

From the Magicicada.org website:

Periodical cicadas are unique in their combination of long, prime-numbered life cycles (13 or 17 years), precisely timed mass emergences, and active choruses.
Periodical cicadas are found only in eastern North America. There are seven species -- four with 13-year life cycles and three with 17-year cycles. The three 17-year species are generally northern in distribution, while the 13-year species are generally southern and midwestern. The periodical cicadas can be divided into three species groups (-decim, -cassini, and -decula) with slight ecological differences. Magicicada are so synchronized developmentally that they are nearly absent as adults in the 12 or 16 years between emergences. When they do emerge after their long juvenile periods, they do so in huge numbers, forming much denser aggregations than those achieved by most other cicadas. Periodical cicada emergences in different regions are not synchronized, and different populations comprise the 15 largely parapatric periodical cicada "Broods," or year-classes.
Many people know periodical cicadas by the name "17-year locusts" or "13-year locusts", but they are not true locusts, which are a type of grasshopper. Their uniqueness has given them a special appeal and cultural status. Members of the Onondaga Nation near Syracuse NY maintain the oral tradition of being rescued from famine by periodical cicadas. Early European colonists viewed periodical cicadas with a mixture of religious apprehension and loathing. Modern Americans maintain numerous websites to assist in planning weddings, graduations, and other outdoor activities around Magicicada emergences.
Magicicada adults have black bodies and striking red eyes and orange wing veins, with a black "W" near the tips of the forewings. Most emerge in May and June. Some of the annual cicada species are sometimes mistaken for the periodical cicadas, especially those in the genera Diceroprocta and Okanagana; these other species emerge somewhat later in the year but may overlap with Magicicada. The Okanagana species are the most potentially confusing because some have similar black-and-orange coloration. Other Common North American non-periodical cicadas include the large, greenish "dog-day" cicadas (genus Tibicen) found throughout the U.S. in the summer. Non-periodical cicadas are often called "annual cicadas" (even though they typically have multiple-year life cycles) because in a given location adults emerge every year. The best way to identify cicada species is by the sounds that they make, because cicada songs are nearly always species-specific.


 

Posted by Cathy Justis at 10:26 PM