A wealth of fireflies is turning every night in the Richmond area into the Fourth of July. “They are nature’s fireworks,“ said Chris Hobson, a state-employed biologist. That delights Chris and Leslie Hobson’s three young children, who dash about the yard of their New Kent County home in pursuit of the slow-flying beetles. “I just grab ‘em, one hand,“ said Ellie Hobson, 5.

The fireflies on Denise Wade’s property in Montgomery, Texas, are so magical that they remind her of a very different time of year. “I can say safely that there are thousands,“ she says, “and they’re at all levels and they’re blinking like Christmas lights. It’s awesome.“ Wade has seen the number of fireflies increase since she bought her property, but a lot of people have a different experience. In parts of the world where firefly populations have been monitored for a long time, such as Japan, their numbers are down. And scientists think the same might be true in the U.S.