The Collaborative International Dictionary of English v.0.48:

Festucine \Fes*tu*cine\ (? or ?), a. [L. festula stalk, straw.
   Cf. Fescue.]
   Of a straw color; greenish yellow. [Obs.]
   [1913 Webster]

         A little insect of a festucine or pale green. --Sir T.
                                                  Browne.
   [1913 Webster]