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Benefit and Value of Insects

Contact: Diane Relf, Extension Specialist, Environmental Horticulture

Posted April 1997

Insects need to be studied carefully to distinguish the beneficial from the harmful. People have often gone to great trouble and expense to destroy quantities of insects, only to learn later that the insect destroyed was not only harmless but was actually engaged in saving their crops by eating destructive insects. Most entomologists have had correspondents send in the larvae of lady beetles with the complaint that they were injuring plants; at the same time overlooking the smaller aphids which were causing the injury and which these larvae were continually devouring.

Insects are beneficial to the gardener in several ways:

  1. Insects aid in the production of fruits, seeds, vegetables,and flowers, by pollinizing the blossoms. Most common fruits are pollinized by insects. Melons, squash, and many other vegetables require insects to carry their pollen before fruits set. Many ornamental plants, both in the greenhouse and out of doors, are pollinated by insects for example, chrysanthemums, iris, orchids, and yucca.
  2. Parasitic insects destroy other injurious insects by living on or in their bodies and their eggs. Insects also act as predators, capturing and devouring other insects.
  3. Insects destroy various weeds in the same ways that they injure crop plants.
  4. Insects improve the physical condition of the soil and promote its fertility by burrowing throughout the surface layer. Also, the dead bodies and droppings of the insects serve as fertilizer.
  5. Insects perform a valuable service as scavengers by devouring the bodies of dead animals and plants and by burying carcasses and dung.

Many of the benefits from insects enumerated above, although genuine,are insignificant compared with the good that insects do fighting among themselves. There is no doubt that the greatest single factor in keeping plant-feeding insects from overwhelming the rest of the world is that they are fed upon by other insects. It is easy to see how the industry of insects and their devotion to purpose, when coupled with almost unlimited numbers, can benefit us when they seek and devour myriads of pests scattered over a farm or a forest.

(Excerpted from The Virginia Gardener Handbook, Diane Relf, Editor. Department of Horticulture, Virginia Tech, Blacksburg, VA 24061-0327.)

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