Source : Webster's Revised Unabridged Dictionary (1913)

Trehala \Tre*ha"la\, n. (Chem.)
   An amorphous variety of manna obtained from the nests and
   cocoons of a Syrian coleopterous insect ({Larinus maculatus},
   {L. nidificans}, etc.) which feeds on the foliage of a
   variety of thistle. It is used as an article of food, and is
   called also {nest sugar}.