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Northland Nature: Rare natural phenomena inspire cicada safari – Duluth News Tribune
Northland Nature: Rare natural phenomena inspire cicada safari – Duluth News Tribune

This year has brought us some remarkable natural events. Most notable was the total solar eclipse on April 8th, which occurred across much of the country but only partially in this region. On the night of the following month, May 10th, clear skies, no moon and mild temperatures set the stage for a magnificent aurora.

Many black insects with clear and orange wings cling to the tree

A group of 13 year old cicadas.

Article by Larry Weber

These events in April and May were difficult to follow, but June also brought some phenomena of its own: the massive appearance of the 13-year and 17-year cicadas. I found that the presence of these two species in some of the states to our south was so great that I did not want to experience it. In the last days of May and early June, I left the Northland to experience this insect phenomenon in two other states: Missouri and Illinois.

Cicadas are sturdy insects with wings that extend beyond their 1-inch-long bodies. The head section consists of short antennae, fairly large eyes, and a protruding mouth part that can be used to suck sap from tree branches. They are classified as members of the order Heteroptera (formerly Homoptera). Insects in this group are collectively known as “true” bugs.

Two black insects with large wings and red eyes cling to a green leaf

Two 13 year old cicadas.

Article by Larry Weber

There are several species of cicadas in our area: a cicada active in July that makes hissing sounds and one in August that emits a whining call is known as the buzzsaw cicada or dog-day cicada. Both have dark eyes. The July cicada has orange markings on its body while the latter is green. The cicadas I looked at had dark bodies with red eyes.

Our cicadas have life cycles in which they go through an immature stage where they live underground for about a year before growing into adults.

They are known as annual cicadas. In other parts of the country, some cicadas periodically emerge from their 13- or 17-year lives as underground juveniles. During this time, they feed on tree roots and grow to adulthood.

Many black insects with clear and orange wings cling to the tree

A group of 17-year-old cicadas.

Article by Larry Weber

For the breeding season to be successful, they must all reach adulthood at the same time. Therefore, these hatchlings are filled with thousands (millions) of these insects. Unlike the hatchling of water mayflies or forest tent moths, the male cicadas must call the females. These cicada hatchlings are filled with the sights and sounds of courting and mating insects.

Groups (populations) of cicadas that emerge at specific times are called broods. Somewhere in the country, 13- or 17-year-old cicadas emerge almost every year. What made this year so special was that the broods emerged next to each other; 13 and 17 are prime numbers, so a simultaneous appearance of these two numbers next to each other only occurs once in 221 years (13 times 17). And this was the year.

Orange insect clings to wood

The exoskeleton of a 13-year-old cicada.

Article by Larry Weber

Thirteen-year cicada broods consist of four species, while three species make up 17-year broods. All have their own calls, which are often loud and whose choruses can be deafening. Their mating songs are produced by vibrating the abdomen. Although it sounded like a constant roar, as I listened to the ongoing cacophony, I could tell differences.

Most of the sounds sounded like dragging chains (crickets), but there were also “squawks” and occasionally a very loud “woohoo” sound from the crowd. Sometimes these are mixed with piercing shrieks. After waiting so long to mate and lay eggs, the animals mate in the trees all day long, from morning to evening.

Northland Nature_2 Cicada Exoskeletons

Two exoskeletons of 17-year-old cicadas.

Article by Larry Weber

The young dig their way out of their underground burrows, climb up tree trunks, and in the darkness the adult bodies emerge from the juvenile exoskeleton. The exoskeletons are left on the tree trunks (or other substrates). Some of the burrows that hatch are filled with these “shells.” Although they have fairly long wings, they do not fly far, so reproduction occurs in the same place as the previous generation.

A lot has changed in 13 or 17 years, but they find trees. During my hikes to observe this explosion of insects, I noticed that the biggest activity seems to be in large and old trees.

My route on this safari took me to Missouri where I was able to observe the 13-year-olds. This was often very easy and happened right in towns, gardens and parks. In most parts of the state this 13-year-old phenomenon could be observed.

red and black insects crawl up a branch

A group of 13-year-old cicadas.

Article by Larry Weber

As I headed east toward Illinois, I continued to see and hear the 13-year variety, but as I moved north in that state, near Wisconsin, I found myself in the territory of the 17-year cicadas.

Both put on quite a show and although they were numerous and noisy, they are harmless. Unfortunately, in parts of the country they are called “locusts” (a type of grasshopper that does not resemble cicadas). Apparently this inaccurate name was given to the cicadas during a mass emergence. To the people living there, it looked like a “plague of locusts”. They are noisy but harmless to us and only feed on sap from the tips of tree branches.

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

Larry Weber

Larry Weber

Larry Weber

Retired teacher Larry Weber, a resident of Barnum, is the author of several books.

By Liam