NC State University Department of Statistics. Click to enlarge.

"What do you call the insect that flies around in the summer and has a rear section that glows in the dark?"

Bert Vaux, a linguistics professor at the University of Cambridge, asked 10,000 Americans around the country that question and others relating to regional dialects. If you use "firefly" and "lightning bug" interchangeably, like I do, you're in good company. Across the United States, 39.8 percent of respondents report using both terms. 30.4 percent say “firefly” exclusively and 29.1 percent say “lightning bug.” Meanwhile, 0.02 percent (or two people total in the study) call the bioluminescent bugs “peenie wallie” (perhaps they wanted to hurt the beetles' feelings).

Joshua Katz, a graduate student in statistics at NC State University, turned the survey data into the map you see above, which shows how the exclusive use of "firefly" is a western phenomenon, with a small enclave of support in Massachusetts.

The Afternoon Map is a semi-regular feature in which we post maps and infographics. In the afternoon. Semi-regularly.