The sun is setting and the sky above Dave and Christine McComas' house in Woodbine turns pink, signaling that the curtain is about to go up on tonight's show.
Soon, the wildflower meadow behind their home begins to sparkle, hundreds of lightning bugs floating upward. Ten-year-old Gloria and her friend, Mariel Frith, also 10, leap to catch the fireflies before they dim and disappear.
"We need to do it gracefully," Gloria shouts, laughing.
Lightning bugs are easier to catch than they are to count. But if you have the sense that there are more of them lighting up the summer night this year than in years past, you might be right.
After several years of decline in the lightning bug population, scientists say there could be a resurgence in the number and species of the beetles that lit the summer nights of our youth.
"The big drivers would be changes in climatic conditions," said Michael Raupp, professor of entomology at the University of Maryland and author of the blog Bug of the Week (bugoftheweek.com).
"It could be that the winter was more benign, that the larval stages [that live in the ground] had better food and the weather conditions are better for mating and laying eggs. Or there could be a drop in the number of predators."
Lightning bugs live a life as dramatic as their evening performance. After a year or two in the ground eating worms, grubs and slugs, they emerge and put on a light show to attract a mate.
They are aboveground for only a couple of weeks before they mate, leave their eggs in the soil and die. They don't even stop to eat, unless it is a bit of pollen or a sip of nectar.
"The most spectacular displays happen where the meadow reaches the forest edge," said Raupp, who stalks bugs with his camera. The larvae also glow, and he finds them "winking along at nighttime like little trains in the soil."
"The signaling starts low in the grass, where they have been resting all day, and slowly moves up to the tree canopy. And they love hot, humid weather," said Christine McComas.
She and her husband and four daughters live on about 31/2 acres in Howard County, and she has converted an acre at the back of their property to a wildlife habitat, planting native wildflowers and 150 trees.
Fireflies couldn't ask for a better place to hang out, and they reward her family with nightly magic.
"Once it flashes, I can see the whole body for a minute," said Gloria. "They give themselves away, like little lanterns saying, 'Here I am.'"
"I don't have to do anything," said Mariel. "They just come to you. They land on my finger and invite their friends for a party, and I catch them."
Torin Reilly, 10, visiting a neighbor from Selinsgrove, Pa., joins the girls in the deep twilight underneath a sugar maple tree as they fill up a pickle jar with lightning bugs, but he doesn't understand why the jar goes mysteriously dark.
"They don't flash in jars," explained Raupp. "Freaks them out."
The Museum of Science in Boston launched a project in 2008 to try to track lightning bugs, and they have "counters" who send in reports on the color of the flash — from pale green to yellow — and the flash patterns.
But Don Salvatore, who oversees the Firefly Watch, thinks it will be years of counting before scientists have a handle on the population, the number of species and their geographic haunts.
"We have a lot of anecdotal evidence," said Salvatore. "But we have never had any data." More than 5,000 "watchers" count the fireflies in their backyards during a 10-second period on a summer evening and report the numbers to him.
He has counters in 38 states, but there are no fireflies west of the Rockies and they are scarce in the Southwest.
"We had friends visit from Texas, and they couldn't believe it," said Christine McComas, who works for the University of Maryland Extension's Home and Garden Information Center. "It was amazing for them."
Raupp believes that any downturn in the population, which became noticeable in 2008, was the result of pressure on the lightning bug habitat. Too many concrete parking lots left less ground for the larvae to inhabit while they develop. Pesticides shrank the food supply of slugs, grubs and worms.
And light — from streetlights, houses, parking lots and even baseball stadiums — confused the fireflies, who couldn't "find" each other.
In addition, pesticides on lawns would have crippled the female lightning bug populations, because that's where they stay.
Researcher Sara Lewis at Tufts University has concluded that the intensity or the frequency of the male's flash indicates the quality of the protein packet that he carries and deposits during mating. That protein can sustain the 500 eggs the female will lay.
"There are evolutionary underpinnings to the display," said Raupp.
But Torin wants to know the secret of the flash.
"Light is produced by specialized cells in the abdomen," says Raupp. "The cells contain a chemical called luciferin and the enzyme luciferase."
When combined with oxygen, which arrives by air tubes in the cells, a chemical reaction produces the heatless light. The lightning bug controls the flashes by regulating the amount of air it takes in.
"It is a true marvel of chemistry," said Raupp. "And it is mystical. These creatures have the ability to create light."
The light also serves as a warning to birds and spiders, who find the firefly distasteful enough to avoid.
McComas, who has used her training from Maryland Extension to create the wildlife wonderland the fireflies inhabit, says the past two years have been particularly good for lightning bugs because of the rain and snow, which kept the ground moist for the larvae.
"It has made us see them with new eyes," she said.
"We have one rule. You have to let them go at the end of the night."