{"id":17311,"date":"2019-07-24T18:32:28","date_gmt":"2019-07-24T18:32:28","guid":{"rendered":"https:\/\/www.lifeandnews.com\/articles\/?p=17311"},"modified":"2019-07-25T16:56:14","modified_gmt":"2019-07-25T16:56:14","slug":"how-fireflies-glow-and-what-signals-theyre-sending","status":"publish","type":"post","link":"https:\/\/www.lifeandnews.com\/articles\/how-fireflies-glow-and-what-signals-theyre-sending\/","title":{"rendered":"How fireflies glow \u2013 and what signals they’re sending"},"content":{"rendered":"

Clyde Sorenson<\/a>, North Carolina State University<\/a><\/em><\/p>\n

You might not really be sure you saw what you think you saw when the first one shows up. But you stare in the direction of the flicker of light and there it is again \u2013 the first firefly of the evening. If you are in good firefly habitat, soon there are dozens, or even hundreds, of the insects flying about, flashing their mysterious signals.<\/p>\n

Fireflies \u2013 alternatively known as lightning bugs in much of the United States \u2013 are neither flies nor bugs. They\u2019re soft-winged beetles, related to click beetles and others. The most dramatic aspect of their biology is that they can produce light<\/a>; this ability in a living organism, called bioluminescence, is relatively rare.<\/p>\n

I\u2019m an entomologist who does research on, and teaches about, the ecology and biology of insects. Recently, I\u2019ve been trying to understand the diversity and ecology of fireflies<\/a> in my home state of North Carolina. Fireflies are found widely across North America, including many places in the west, but they are most abundant and diverse in the eastern half of the continent, from Florida to southern Canada.<\/p>\n

Bioluminescent beetles<\/h2>\n
\"\"<\/a>
A chemical reaction in the beetle\u2019s abdomen gives it its bioluminescence.<\/span>
\nCathy Keifer\/Shutterstock.com<\/a><\/span><\/figcaption><\/figure>\n

Fireflies produce light in special organs in their abdomens by combining a chemical called luciferin, enzymes called luciferases, oxygen and the fuel for cellular work, ATP. Entomologists think they control their flashing by regulating how much oxygen goes to their light-producing organs.<\/p>\n

Fireflies probably originally evolved the ability to light up as a way to ward off predators, but now they mostly use this ability to find mates. Interestingly, not all fireflies produce light; there are several species that are day-flying<\/a> and apparently rely on the odors of pheromones to find each other.<\/p>\n

Each firefly species has its own signaling system. In most North American species, the males fly around at the right height, in the right habitat and at the right time of night for their species, and flash a signal unique to their kind. The females are sitting on the ground or in vegetation, watching for males. When a female sees one making her species\u2019 signal \u2013 and doing it well \u2013 she flashes back with a species-appropriate flash of her own. Then the two reciprocally signal as the male flies down to her. If everything goes right, they mate.<\/p>\n

A good example is Photinus pyralis<\/em>, a common backyard species often called the Big Dipper. A male flies at dusk about 3 feet off the ground. Every five seconds or so, he makes a one-second flash as he flies in the shape of a \u201cJ.\u201d The female Photinus pyralis<\/em> sits in low vegetation. If she sees a fellow she likes, she waits two seconds before making a half second flash of her own at the third second.<\/p>\n

Some species may \u201ccall\u201d for many hours a night, while others flash for only 20 minutes or so right at dusk. Firefly light communication can get much more complicated; some species have multiple signaling systems, and some might use their light organs for other purposes.<\/p>\n