The presence of large numbers of unwanted animals or pests living in a place, causing problems or disease.
From Latin 'infestare' (to trouble, harass), combining 'in-' (into) and 'festus' (hostile). The word evolved to specifically describe the invasion of pests, particularly in medical and agricultural contexts by the 1600s.
Cockroach infestations are nearly impossible to eliminate completely because roaches can survive for weeks without their heads—the body can still detect chemicals. This is why pest control is more like warfare than simple cleaning.
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