Infestation

Definition

The presence of parasitic, phytophagous, or nuisance arthropods (or other organisms) on or within a host, substrate, or habitat in numbers sufficient to cause harm, discomfort, or economic damage; also, the resulting condition or state of being colonized by such organisms. Distinguished from infection, which involves pathogenic microorganisms. In medical and veterinary entomology, the term typically implies ectoparasites (e.g., lice, fleas, ticks, mites) or internal parasites with visible macroscopic stages; in stored-product and agricultural contexts, it denotes pest populations in grain, timber, or structures.

Etymology

From Latin infestare, to attack, disturb, or molest.

Example

A heavy infestation of Varroa destructor mites on honey bee colonies can vector viruses and cause colony collapse; human pediculosis is an infestation of head lice (Pediculus humanus capitis) on the scalp and hair.

Synonyms

• parasitization (when parasitic)
• pest colonization

Related Terms

• Infection
• Parasite
• Ectoparasite
• Endoparasite
• Vector
• Phoresy
• myiasis
• Pediculosis
• Scabies
• Fumigation
• Integrated Pest Management

Usage Notes

Specialists reserve 'infestation' for arthropods and visible parasites, contrasting with 'infection' for microorganisms. The term can describe population-level phenomena (a building infestation of cockroaches) or individual hosts (a dog's tick infestation). 'Heavy' or 'light' infestation indicates relative density; 'active infestation' confirms living pests present versus past damage. In taxonomy and field ecology, use precise terms like 'parasitized' or 'colonized' to avoid clinical connotations when describing natural host-parasite relationships.