From Longman Dictionary of Contemporary Englisha plague of rats/locusts etca plague of rats/locusts etcINCREASE IN NUMBER OR AMOUNTan uncontrolled and harmful increase in the numbers of a particular animal or insect A plague of squirrels is threatening our forests. → plague
Examples from the Corpus
a plague of rats/locusts etc• From Tracy Luv to Sarah-Lou, Corrie kids are as well-behaved as a plague of locusts.• I wonder what really causes a plague of rats? 