WordNet sense 1 (a serious (sometimes fatal) infection of rodents caused by Yersinia pestis and accidentally transmitted to humans by the bite of a flea that has bitten an infected animal):

pest, pestilence, pestis

WordNet sense 2 (a swarm of insects that attack plants):

infestation

WordNet sense 3 (cause to suffer a blight):

blight

WordNet sense 4 (annoy continually or chronically):

beset, harass, harry, hassle, molest, provoke, chivy, chevvy, chevy, chivvy