Wordnet 3.0
NOUN (2)
1. 
 the state of being invaded or overrun by parasites; 
2. 
 a swarm of insects that attack plants; 
- Example: "a plague of grasshoppers"[syn: infestation, plague]
The Collaborative International Dictionary of English v.0.48:
Infestation \In`fes*ta"tion\, n. [L. infestatio: cf. F.
   infestation.]
   The act of infesting or state of being infested; molestation;
   vexation; annoyance. --Bacon.
   [1913 Webster]
         Free from the infestation of enemies.    --Donne.
   [1913 Webster]
WordNet (r) 3.0 (2006):
infestation
    n 1: the state of being invaded or overrun by parasites
    2: a swarm of insects that attack plants; "a plague of
       grasshoppers" [syn: infestation, plague]