There’s a huge difference between locusts and cicadas

Q: Can you explain the difference between locusts and cicadas? Also, I thought the recent eclipse was supposed to cause cicadas to start singing, but National Public Radio reported that it was crickets that became active. Which one leaves the shells I find?

A: When it comes to confusing insects, it’s the Bible that — unintentionally — may have led us astray.

At least, that’s the thinking of some entomologists who continue to be bugged by why people use the words “locusts” and “cicadas” interchangeably even though the two are not even remotely related.

Here’s the theory: When colonists came upon cicadas for the first time, they didn’t know what to call them, much less how to classify them biologically. Not only that, they found the new insects in such large numbers that it reminded them of the infamous plague of locusts in Exodus 10. As a result, some people still use “cicadas” and “locusts” synonymously when they hear the sometimes deafening “ree-uh, ree-uh, ree-uh” from the cicada armies.

In truth, the two look nothing alike and don’t even belong to the same taxonomic order. Locusts are short-horned grasshoppers. They have mouths that can chew, which makes them the bane of farmers. They also have two pairs of wings — one narrow and the other wide — long hind legs that allow them to jump, and the ability to “vocalize” by rubbing their hind legs against their forewings. They can grow up to 3 inches in length and belong to the order Orthoptera, which includes crickets.

These grasshoppers usually are called locusts when they swarm in large numbers to chow down on crops and other plants. As they start to prowl, the movement of their hind legs apparently causes their brains to secrete more serotonin, which turns their bodies a darker color and causes them to breed abundantly. As food becomes scarce, serotonin also causes them to become both sociable and nomadic, which is why you can find stories of massive swarms traveling 100 miles to satisfy their appetites.

To borrow a Monty Python gagline, cicadas are completely different. Belonging to the order Hemiptera, they have stout bodies, short antennae, long transparent wings and three pairs of legs that are all the same size. Instead of jaws that chew, they have a proboscis in their mouths that they use to suck juices from plants for nourishment. And instead of rubbing their legs against their wings to make noise, they have drumlike membranes below their abdomen called tymbals that produce their distinctive whining that can ramp up to 120 decibels (a jackhammer peaks at about 100). They reportedly could easily drown out a grasshopper/locust.

They come in two types: the annual and periodical cicadas. Annual cicadas are green and can grow up to 2 inches long. They usually make their appearance late in the summer every year and can live up to about five years.

However, it’s the darker colored periodical cicadas that usually grab the headlines. Depending on the variety, they usually spend their first 13 or 17 years underground, using their proboscises to drink plant fluids. When their underground cycle ends, they’ll emerge by the thousands or even millions in the spring, which is likely why they were confused with locusts in the first place. They do not bite or sting, and, for the most part, they cause little damage to plants.

The “shells” you have found are the exoskeletons — or skins — that the cicadas leave behind when they molt from their nymph stage into full adulthood. (Dragonflies, damselflies and mayflies also leave similar remnants behind.)

As for which was affected by the eclipse, NPR was correct. Cicadas usually sing during the heat of the day while crickets chirp away at night. History bears this out. In the summer of 1991, researchers at the University of Illinois and Barry University in Florida traveled to Arizona to observe cicada behavior. During a partial eclipse, they noted that when the sun was more than half covered, the cicadas stopped singing. Apparently the cicada’s call is energy related and even the drop of a few degrees makes it impossible for the insects to maintain the body heat necessary to sing.

In 1932, however, the public reported that crickets became “excessively chirpy” during an eclipse. I’d be interested to know if the current cicada cacophony I hear while bicycling through Ogles subdivision quieted during the Aug. 21 eclipse.

Today’s trivia

How much honey does a worker bee make during its lifetime?

Answer to Wednesday’s trivia: White-knuckle taxi rides apparently have a long tradition in New York City. On May 20, 1899, cabbie Jacob German is thought to be the first person in the United States pulled over for speeding. He was driving his electric vehicle an estimated 12 mph in an 8-mph zone, so a cop on a bicycle pulled him over and took him to the hoosegow. However, it was Harry Myers, of Dayton, Ohio, who may have received the first actual paper ticket in 1904. According to the U.S. Census Bureau, about 112,000 speeding tickets are issued each day or about 41 million a year.

This story was originally published September 7, 2017 at 2:23 PM with the headline "There’s a huge difference between locusts and cicadas."