CHARLESTON — Catching fireflies is a summer tradition which researchers will be relying on during the traditional start to the season to find out how many of them are in South Carolina.

Researchers at Clemson University are asking residents to spend a minute in their yards between 8 and 10 p.m. Friday counting fireflies and recording what they see on a web site.

Scientists are concerned fireflies may be disappearing and the count provides a better idea of the population in the state.

There are about 200 firefly species found east of the Rocky Mountains that flash colors ranging from yellow-green to pale blue.

Since the online Firefly Watch debuted three years ago, people across the county have entered firefly data.