June 2013 A firefly (Photuris lucicrescens) or "lightning bug" is a crepuscular beetle June 2013 Cat lovers love their cats, but let's be honest: Not all cat lovers know cat facts. Here's one common misconception about house cats: Myth: Cats are nocturnal. Fact: The domestic house cat (Felis silvestris catus) is actually crepuscular, which means they …