Flutterfires are a group (perhaps genus?) of Nanodragons mentioned in The Incomplete Book of Dragons.
Being Nanodragons, Flutterfires are around the size of a small mouse or a large insect. They have very butterfly-like wings. "Flutterfire" appears to be a group name, with the Long-Eared Flutterfire being a specific type/species. A different type of Flutterfire appears in The Incomplete Book of Dragons, which does not have the long ears and more round-edged wings.
Flutterfires can shoot fire as most dragons can. Unlike many other Nanodragons, however, Flutterfires are able to speak Dragonese.
Flutterfires frequent open fields with Flowers such as heather and eat the nectar. The nectar does cause them to go into a drunken state, similar to catnip to cats. They also regularly eat insects by roasting them with their fire.
In this reference book, flutterfires are described in the Nanodragon section.