The Collaborative International Dictionary of English v.0.48:

firebrat \firebrat\ n. (Zool.)
   an insect (Thermobia domestica) which is a type of
   bristletail that lives in warm moist areas e.g. around
   furnaces.

   Syn: Thermobia domestica.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

firebrat
    n 1: lives in warm moist areas e.g. around furnaces [syn:
         firebrat, Thermobia domestica]