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What is a pest?

A pest is a plant, animal, or microorganism that has a negative effect on humans. It could be a germ, algae, weed, nematode, insect, spider, mite, bird, fish, rodent or even a deer. Labeling an organism a pest is a very subjective concept that varies with each individual’s point of view. In general, pests are unwanted or undesirable because they:

• reduce the availability, quality, or value of human resources such as food, feed, water, or space;
• injure humans, animals, crops, structures, and possessions;
• spread or cause disease;
• interfere with our activities by causing annoyance, discomfort, or inconvenience.

Many organisms may become pests, certain organisms are often pests, but
none are inherently pests.

Identifying pests is the first step toward managing them. The following links will help you identify pests and their natural enemies.

University of Maine, Insect & Plant Disease Diagnostic Lab

Maine's top 11 beneficial insects and spiders

UC IPM Pest Identification Helpers

UC IPM Natural Enemies Gallery

Definition of pest

Pests can be insects, mice and other animals, unwanted plants (weeds), fungi, or microorganisms like bacteria and viruses.

Innocent bystanders

Before you swat, stamp or spray.know your enemy. Over 97 percent of insects in and around the home are beneficial or innocent bystanders.

Maine's top 11 beneficial insects and spiders [pdf]