cankerworm

noun

1. Either of two caterpillars, the larvae of geometrid moths, that are destructive to fruit, buds and leaves.
2. 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?”