text: Leah Hogsten | The Salt Lake Tribune) A visitor to Thompson Century Farm tries to catch a firefly. Fireflies have been twinkling in the hay fields of Diane Garcia's family farm, Thompson Century Farm near Spanish Fork, since her great-great-grandfather Samuel Thompson settled the farm in 1800s. The farm and its wet, marshy habitat is perfect for the fireflies' annual mating rituals every year, roughly from late May to early July. Garcia leads tours through her fields for free, simply to share in the experience and to educate others about fireflies, their short-lived lifecycle and what endangers their fragile habitat.