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Cicada Weather Predictors

August 14, 2015
Apache cicada (Photo credit: Jay W. Sharp)

Apache cicada (Photo credit: Jay W. Sharp)

In June while on a family trip to visit the Grand Canyon we took a side excursion to Montezuma Castle National Monument near Camp Verde, Arizona. We stopped to see the cliff dwellings of the Ancestral Puebloan people who resided there some 1000 years ago.

The cliff dwellings carved into the rock high up the mountainside in that hot and dry Arizona environment were interesting. So was the little canal these ancient people had constructed to provide water for crop growth in this arid environment. But I must admit that what really caught my attention was what sounded like cicadas singing from the sycamore and cottonwood trees growing in the valley below the cliff dwellings.

I was unable to spot any of the singing insects, so I asked one of the naturalists if the sound was, as I suspected, that of cicadas. I was told it was and that every year these insects begin singing around this time. I was also informed that singing cicadas are a welcome sound in the area because it means the monsoon season is about to begin.

When I think of monsoons I always envision rainy seasons associated with Africa, Asia or Australia. But there are also North American changes in wind direction that bring rain to parts of Arizona. These events are often called desert, Sonoran or Mojave monsoons. As you probably imagine, the amount of rain associated with these desert monsoons – less than 12 inches annually at Montezuma Castle – pales in comparison to the rainfall associated with monsoons in the rest of the world; however, even the small amount of precipitation that does fall is important to the flora and fauna of the desert.

As it turns out, the type of cicada that was said to predict the arrival of the desert monsoons is called the Apache cicada. It is a species of cicada that emerges every year in the areas where it is found. Generally, cicadas with this emergence pattern are called annual cicadas.

When many people hear the word cicada they think of periodical cicadas. These species of cicadas spend 13 or 17 years feeding underground before emerging. The periodical cicadas are only found in eastern North America and emerge in great masses in late May and June as they did in some parts of the country in 2015. As is the case for all cicadas, the males sing to attract mates.

This was not the first time that I had heard of cicadas being used to predict a weather event. When I was growing up on a Kansas farm I recall that almost every year during August my father would announce “six weeks ‘til frost.” His confident prognostication was based on the fact that he had heard a cicada singing. So like my father before me, and probably his father before him, the first time I hear a cicada singing each year I am immediately reminded that fall is on the way.

The cicadas on which my father based his first-frost prediction are sometimes called dog day cicadas. That name is based on the appearance of the cicadas about the time that Sirius - the dog star - is visible at sunrise during late July and early August. Some dog day cicadas, as do Apache cicadas, emerge every year after spending 2-4 years developing below ground where they suck sap from the roots of trees.

I am not sure how the idea of using cicadas to predict something such as desert monsoons or the first frost of the year originated. I suspect that such a prediction might have developed during a time when humans used observations in nature to predict other events. Many predictions like this use what are called phenological indicators: stages of plant development such as budding, the appearance of leaves or blossoms. An example is the old saying that it was time to plant corn when the oak leaf is the size of a squirrel’s ear.

I have no idea about how accurate such predictions might be. I wouldn’t put much weight on the specifics, but on the average they might have some merit. This year I heard the first dog day cicada at my place in Indiana during the last week of July. That means the first frost will be in mid-September. You heard it here first!

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