Some Americans say 'firefly' while others say 'lightning bug,' and a series of maps highlights an interesting theory why

Shutterstock/SirinartCJWhat do you call this glowing insect — a firefly or a lightning bug?
  • In the United States, glowing insects are known as “fireflies” or “lightning bugs” depending on where you live.
  • “Firefly” is the more common term in the West and New England, while people in the South and most of the Midwest tend to say “lightning bug.”
  • There’s an interesting theory to explain why the two competing terms emerged, and it has to do with the natural surroundings of the two regions.

The natural world has influenced the way we speak for as long as language has been around.

In English, we’ve taken plenty of idioms from our natural surroundings: “the coast is clear,” “go out on a limb,” and “wild goose chase,” to name a few.

But the environment has a much more subtle effect on our language, too. Take a look at this map from Josh Katz, author of “Speaking American: How Y’all, Youse, and You Guys Talk.” It shows where in the United States people tend to say “fireflies” or “lightning bugs” to refer to the little glowing insect we see in the summertime:

Dialect mapJosh Katz

It’s one of many examples of things that have different names in different parts of the US.

But it goes deeper. As meteorological researcher Jason Keeler noted on Twitter, the areas where people say “lightning bug” seem to overlap with the parts of the country where lightning strikes are particularly frequent (the purple area in the map below):

Lightning mapTwitter/Jason Keeler

Meanwhile, “firefly” is the more common term in most of the West, which just so happens to be the region that experiences the most wildfires:

Wildfire mapTwitter/Jason Keeler

The correlation could be a mere coincidence, as American Dialect Society member John Baker told Business Insider. “But it also seems reasonable that people are subconsciously reminded of the locally more prominent risk when referring to these insects, though neither fire nor lightning is involved in any way,” he said in an email.

While more research would need to be done to see if Keeler’s observation has linguistic merit, it’s certainly thought-provoking that the type of weather in a region could influence the local term for an insect.

Interestingly, the firefly/lightning bug divide has a surprisingly rich and well-documented history. In 1949, linguist Hans Kurath found that “firefly” was particularly popular in large cities on the East Coast. Later, the Dictionary of American Regional English found that “lightning bug” was the more common term in the South and Midwest, but not the Pacific coast. New York City seems to be caught in the middle: according to Katz, 86% of Manhattan residents say “firefly,” while 60% of people on Staten Island say “lightning bug.”

Those aren’t even the only two names for it, lexicographer and American English expert David Barnhart told Business Insider. Depending on what part of the country you’re in, you may have grown up calling it a candlefly, firebob, firebug, glowworm, jack-o-lantern, lamp bug, or will-o’-the-wisp.

No matter what you call it, the divide between “firefly” and “lightning bug” is just one of the linguistic quirks that makes American English such an intriguing dialect.

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