Is There a Difference Between a Cicada and a Locust?

Updated on May 10, 2013
Cicada | Source

In spring and summer when insects become active once again, two bugs that we sometimes hear about are cicadas and locusts (especially when there's a significant "swarm" expected). Sometimes, people use the two words interchangeably for the same insects. Is this acceptable, or is there a difference between a cicada and a locust?

Yes, there is a difference between a cicada and a locust.

Cicadas and locusts are in fact different insects. They aren't even from the same order. They are often confused with each other due to their behavior. Locusts swarm, and periodic cicadas are often thought to swarm. However, cicadas don't actually swarm - they just happen to be above the ground in large numbers at the same time. The association between cicadas and locusts goes back to colonial times. When periodical cicadas showed up in large numbers, the colonists assumed they were experiencing a "locust plague", similar to the ones in the Bible.

Desert locust
Desert locust | Source

What's a locust?

A locust is a type of grasshopper from the family Acrididae. These insects do in fact swarm when they reach adulthood, and they cause significant damage to crops and fields (even as nymphs). The only distinction between a locust and a non-locust grasshopper is the swarming behavior. Locusts don't always swarm, however. They do so after periods of wet weather, which leads to areas of overcrowding (when the plants begin to die, the locusts all make their way to the remaining food). Then, the insects bump into each other and activate hormones. The hormones cause them to change color, breed even more, and synch up their growth and egg-laying. When they run out of food in their area, they'll all fly together in a swarm to find something else to eat. They can travel up to 100 miles each day.

Cicada | Source

What's a cicada?

A cicada is an insect from the order Hemiptera and superfamily Cicadoidea. There are over 2,500 known species of cicadas, and they live throughout much of the world. Cicadas spend most of their lives underground, where they live off the xylem of plants. When they come close to the end of their lives, they emerge from the ground to mate. Adult cicadas are most recognizable by their prominent eyes, and many species have transparent wings. Each cicada species has its own mating song, which is "performed" by the males using structures called tymbals. Some cicada songs can be as loud as 120 decibels, which puts them among the noisiest insects. This loud noise has an added benefit for the cicadas - it keeps away predators such as birds.

Are there different types of cicadas?

Some cicadas are annual and show up every year, and others (the ones that are often confused with locusts) are periodic. Annual cicadas are also known as "dog day" cicadas, since they are most common during the "dog days" of late summer. They're greenish in color, can be as large as 2 inches, and are heard more often than they're seen. They have a lifespan of 2 - 5 years.

Periodical cicadas are the ones most often mistaken for locusts. They show up earlier in the year than annual cicadas - in spring when the temperature of the soil at 8 inches below ground reaches 63 degrees Fahrenheit. Their lifespan is 13 or 17 years, and the cicadas in a particular region that have their life cycles synched are grouped into a "brood." An example of this is "Brood II", which is due to emerge in much of the East Coast in 2013. When millions of cicadas are active at the same time, it can certainly seem like a swarm.

Unlike locusts, cicadas don't destroy crops. They don't sting, and they generally don't bite. However, they have been known to mistake a human for a tree, and it hurts if they poke you with their proboscis while looking for food. Even though they generally are not harmful, they can be annoying to many people, mainly due to the noise. Due to the huge numbers of cicadas that are active at once, the sound of a cicada invasion can be deafening. Those who live in an area with an emerging brood may wish to consider using earplugs or noise-canceling headphones during the weeks the insects are active.


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    • jenb0128 profile image

      Jennifer Bridges 4 years ago from Michigan

      Thanks for reading and commenting, everyone!

      As far as the "17-year locusts" - yep, that term just came from the confusion between cicadas and locusts. Locusts live normal grasshopper lifespans (the lifespan varies from species to species, but it's usually around 5 - 6 months).

      @pstraubie48: Yes, those would be cicada "skins." I remember having a small collection of them when I was a kid. They were definitely so much fun to find! :)

    • SidKemp profile image

      Sid Kemp 4 years ago from Boca Raton, Florida (near Miami and Palm Beach)

      Thanks - this clarifies something I've been wondering about for a long-time. And I want to follow up on the question from AvianNotice - is it only cicadas who have the long periods (13 and 17 years). Or are there also things like 7-year and 17-year locusts?

    • aviannovice profile image

      Deb Hirt 4 years ago from Stillwater, OK

      This is a fabulous piece, Jen. It was very well done, and answers many questions? Now, where did the mention of the 17-year locust come from?

    • pstraubie48 profile image

      Patricia Scott 4 years ago from sunny Florida

      This is very interesting, well organized, and filled in some details that I need to know. If I am not mistaken, the fascinating outer covering of the cicada was what we would delight in finding around our property in the late summer. Would that be correct?

      I looked on google images and it seemed to be the same one.

      Thanks for sharing with us.

      Sending Angels to you this afternoon. :) ps

    • kashmir56 profile image

      Thomas Silvia 4 years ago from Massachusetts

      Hi Jen this is a very interesting and informative article, some of this information i did not know before, thanks for helping learn more about these little critters .

      Vote up and more !!!