cankerworm

noun

1. Either of two caterpillars, the larvae of geometrid moths, that are destructive to fruit, buds and leaves.
2. (figuratively)A corrupting or destructive force.

   “O cursed Eld the cankerworme of writs, / How may these rimes, so rude as doth appeare, / Hope to endure, sith workes of heauenly wits / Are quite deuourd, and brought to nought by little bits?”