CHICAGO (WBBM NEWSRADIO) — It wasn’t your imagination; Chicagoland hasn’t seen as many fireflies this summer. Allen Lawrence, an associate curator of entomology at the Peggy Notebaert Nature Museum, spoke to WBBM and explained why.
“They were definitely delayed this year,” Lawrence said. “I think [it’s] likely due to the drought that we were experiencing, because they do depend on moist conditions.”
In drier conditions, firefly larvae and eggs, specifically, have a hard time surviving. That’s because, in part, the tiny snails and pill bugs on which the larvae feed need rain and damp soil to come out. Without those conditions, it’s hard for the larvae to get a meal.
Fireflies — or lightning bugs, as many call them — use an enzyme called luciferin to attract mates. Lawrence said the flashing is specific to each species of adult firefly, but their offspring also emit it.
“The larvae also glow because most fireflies, in general, are not very tasty to predators — so it’s sort of a warning signal,” he said.
That’s important because young fireflies stay at the larval stage for about two years. Lawrence said that protection is part of the reason why photuris fireflies light up.
“The females will flash the signals of a different species of firefly, draw the males in and then eat them,” he said. “They’re able to incorporate those defensive compounds into their own body.”
The most common firefly in the U.S. is nicknamed the Big Dipper, because it flies in a pattern that looks like the letter J.
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