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Pest insects — The classification of an insect as a pest is a subjective one, based on its potential damage to human needs and/or natural habitats and ecosystems.

Pest insects can: damage or kill agricultural crops, ornamental plants, or native plants in situ; consume and/or damage harvested food; cause illness or unproductivity in agricultural animals (ie: cattle); and vector human diseases or cause pain.
Some insects are beneficial at one stage of life and a pest at another stage, for example many lepidopterans may be serious pests as larvae, while they may be pollinators in adulthood.
Some insects that are considered pests in human settlements/gardens are actually more a beneficial insect than pestiferous: example: bees (the main pollinators of human food supplies).