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Home > Is It Really a Pest?

Is It Really a Pest?

What Is a Pest?

A pest is any living thing—a plant, an animal, or a microorganism—that has a negative effect on humans. It can be an unwanted plant (weed), fungi, nematode, microbe (such as bacteria or virus), 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; or
  • interfere with human activities by causing annoyance, discomfort, or inconvenience.

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

Beneficial Bugs and Innocent Bystanders

Before you swat, stomp, or spray, know your enemy. Know your friends, too. Over 97 percent of insects in and around the home are beneficial or innocent bystanders. Even critters we often think of as pests can play an important role in the ecosystem, such as food for fish and birds (mosquitoes and blackflies), eating garden pests (wasps), pollinating fruit trees (bees) and more. Birds, mammals, plants and microorganisms may also be beneficial organisms that can be impacted by pesticide applications. Use the GotPests website to help identify pests and beneficial organisms.


More Information about Beneficial Organisms


It is the policy of the State of Maine to minimize reliance on pesticides. The Maine Department of Agriculture and the Maine IPM Council encourage everyone to practice integrated pest management and to use pesticides only as a last resort. The mention of pesticides in the fact sheets linked to these pages does not imply an endorsement of any product. Be sure that any product used is currently registered and follow all label directions.