Crowds will gather in two forests in the United States in coming weeks to see light shows created by a rare species of firefly . These fireflies have the ability to light up with others at the same time . The insects stay lit for 10 seconds , go dark for about a minute , then shine bright again . “ You ’ re standing in a dark forest and suddenly there is a brilliance of little lights everywhere , ” said Tara Cornelisse . She spoke to the Reuters news agency . Cornelisse is a scientist with the Center for Biological Diversity in Portland , Oregon . Visitors gather to watch synchronous fireflies , which appear each year from the middle of May until the beginning of June , as they light up along the Bluff Trail at Congaree National Park in Hopkins , South Carolina , U . S . , May 21 , 2019 Scientists are not sure why some fireflies light up at the exact same time . But they believe that it helps attract reproductive partners during the weeks - long mating season . Three years ago , Cornelisse traveled to the Pennsylvania Firefly Festival in the Allegheny National Forest to see the light show . Cornelisse said of the experience , “ It ’ s like the Milky Way flashes on and then off . You hear people gasp ‘ Ohhhh ! ’” Synchronous fireflies are found only in a handful of places in the United States . In addition to the Allegheny National Forest , they light up the night sky in Tennessee at the Great Smoky Mountains National Park and Oak Ridge Wildlife Management Area . Others are found in South Carolina ’ s Congaree National Park , and around Cajon Bonito Creek in Arizona . This list of places comes from the website Firefly . org . Other synchronous firefly species are found in Southeast Asia . Starting life undergroundFireflies live for two years under Earth ’ s surface as larvae . They feed on worms and snails , creatures that live mainly underground , notes Sara Lewis . She wrote a book called “ Silent Sparks : The Wondrous World of Fireflies . ” She is a professor at Tufts University in Massachusetts . Once the fireflies are adults , they rise up above the ground to spend a few weeks finding a partner , mating and making eggs before they die , said Lewis . She added that researchers “ know very little about why … ( the fireflies ) developed this behavior that makes them an eco - tourist attraction . ” Loss of firefliesThe Great Smoky Mountains National Park is making final preparations for the crowds of people coming to see its light show . Park service officials found a way to limit the number of vehicles entering the park . They set up a lottery for the 1 , 800 parking spaces on the grounds . More than 28 , 000 people entered the competition . People from over 40 states and as far away as Taiwan won the chance to leave their car near the park ’ s entrance in Townsend , Tennessee . Tickets sold out in 12 hours for a 2019 light show in the Allegheny forest on June 22 , said Peggy Butler , the event ’ s organizer . The park is a short drive from the small town of Tionesta , home to fewer than 500 people . This year , officials are trying to limit the crowd to 800 . Organizers said many visitors who come to the firefly events are from Asia . Butler said , “ They want to see the fireflies they remember but don ’ t see any more in places like China and Japan , where human impact and human encroachment on the environment has led to the loss of the firefly . ” There are 2 , 000 different kinds of fireflies worldwide , lighting up the night sky in yellow , green or blue . In Asia , synchronous males remain in mangrove trees , timing their flashes to interest flying females . The situation is generally the opposite in North America , where it is the males who are flying around flashing and the females are sitting on the ground , Lewis said . The downside to firefly light shows is the likelihood that without crowd controls and limits , humans will destroy the very thing that drew them there in the first place . “ There is a danger in just the presence of those people , ” Lewis said . “ You could actually wipe out the population that is so attractive . ” I ' m Bryan Lynn . We want to hear from you . Write to us in the Comments section , and visit our Facebook page . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _________________________ Words in This Story brilliance – adj . intense light or brightnessflash - n . a sudden burst of bright lightgasp – n . the sound made of a person breathing heavilysynchronous – adj . existing at the same timelarvae – n . the active , developing form of an insecteco - tourist – n . people who travel for please to see wild , often threatened natural environmentsimpact – n . the effect or influence of one person or thingencroachment – n . the invasion of one ’ s territory or rightswipe out - v . to destroydraw - v . to pull or act like a magnetSummer Theater : Fireflies That Light Up at the Same Time https : / / learningenglish . voanews . com / a / summer - theater - fireflies - that - light - up - at - the - same - time / 4935850 . html