Northland Nature: Rare natural phenomena inspire cicada safari

Jun. 21—This year has given us some remarkable natural happenings. Notable has been the

total solar eclipse

of much of the country —

partial in this region

— on April 8. In the following month, the night of May 10, with clear skies, no moon and mild temperatures set the stage for a magnificent display of

aurora borealis.

These events of April and May were hard acts to follow, but June also gave some phenomena of its own: the massive emergence of the 13-year and 17-year cicadas. I found the occurrence of these two near each other in some of the states to the south of us was too great not to experience. During the final days of May and early days of June, I left the Northland to witness this insect extravagance in two other states: Missouri and Illinois.

Cicadas are stout insects that have wings extending beyond their inch-long bodies. Short antennae, fairly large eyes and a protruding mouth part used to extract sap on tree twigs make up the head region. They are classified as members of the order Heteroptera (formerly Homoptera). Insects in this group are collectively called "true" bugs.

We have a couple species of cicadas in our region: one active in July makes chipping sounds and one in August that produces a whining type of call is known as the buzz-saw cicada or dog-day cicada. Both have dark eyes. The July one has orange markings on the body while the later one is green. The cicadas that I went to see had dark bodies with red eyes.

Our cicadas have life cycles in which they have an immature stage where they live underground for about one year before emerging into an adult.

They are known as annual cicadas. In other parts of the country, some cicadas have a periodical emergence from a life of either 13 or 17 years as subterranean youth. During this time, they feed on the roots of trees and grow toward adulthood.

To be successful in breeding, they need to all reach adulthood at the same time. And so, these adult emergences are filled with thousands (millions) of these insects. Unlike the emergence of mayflies from water or forest tent caterpillars, the male cicadas need to call the females, these cicada times are filled with the sights and sounds of courting and mating insects.

Groups (populations) of cicadas emerging at set times are called broods. Somewhere in the country, nearly every year is an emergence of 13-year or 17-year cicadas. What made this year so special is that the broods were emerging next to each other;13 and 17 are prime numbers, so an emergence of these two at the same time near each other will happen only once in 221 years (13 times 17). And this was the year.

Thirteen-year cicada broods are composed of four species while three species make up the 17-year broods. All have their own calls, often loud and the choruses can be deafening. Their courting songs are produced by vibrating the abdomen. Though sounding like a constant roar as I listened to the persistent cacophony, I was able to discern differences.

Most of the noise sounded like dragging chains, (crickets), but mixed with these were "caw" types, and occasionally, a very loud "wee-oo" sound emanated from the crowd. Sometimes these are blended with penetrating screeches. After waiting so long to mate and lay eggs, the match-making takes place in trees all day, from dawn to dusk.

The immatures dig out of their underground sites, climb up tree trunks, and in the darkness, the adult bodies emerge from the youthful exoskeleton. The exoskeletons are left on the tree trunks (or other substrates). Some emerging sites are filled with these "shells." Despite fairly long wings, they do not fly far, so breeding is done in the same locale as the previous generation.

Much has changed over 13 or 17 years, but they find trees. During my wanderings to observe this insect explosion, I found large and old trees seem to have the most happening.

My route on this safari was to drive to Missouri where I was able to experience the 13-year ones. This was often easy to do, happening right in towns, yards and parks. Most of the state was experiencing this 13-year phenomenon.

Going east into Illinois, I continued to see and hear the 13-year species, but as I went north in that state, near Wisconsin, I was in the territory of the 17-year cicadas.

Both gave quite a show and though abundant and loud, they are harmless. Unfortunately, they are called "locusts" (a type of grasshopper that does not resemble cicadas) in parts of the country. Apparently, this inaccurate name was applied to the cicadas during a mass emergence. To the people living there, it looked like a "plague of locusts." They are loud but harmless to us, feeding only on sap from the tips of tree twigs.

Even the Latin names tell of their strange life cycle: 13-year cicadas are Magicicada tredecim and the 17-year cicadas are Magicicada septendecim. Thirteen-year cicadas were last seen here in 2011; the next time will be 2037. Seventeen-year cicadas were last seen here in 2007; the next time will be 2041. I suggest making plans to see these coming natural phenomena.