Crop pests are organisms which damage crops and livestock. They cause serious problem on the farm; they reduce the yield and quality of food produced by farmers in that they destroy crops. Some common pests of crop plants are insects, rodents, birds, monkeys, bats, humans, molluscs,  nematodes and weeds.

Classification of crop pests based on mouth part

Insect pest belong to a group of organisms known as arthropods. They have small body size, rapid rate of reproduction and can easily adapt to various climatic conditions. Insect pests can be classified into three groups based on their mouth parts.

Piercing and sucking insects: These are insects which have long powerful, piercing proboscis used for sucking liquid cell contents of plants parts. They suck cell sap and inject toxins (poisonous substances) into plants. The wounds created can serve as source of secondary infection. The commonest examples of piercing and sucking insects are scale insect, whitefly, cotton stainer, aphid, capsid etc.

Biting and chewing insects: They have mouth parts made up of strong pair of toothed horny jaws, accessory jaws and lower lips. Biting and chewing insects feed on plant parts such as leaves, flowers, and fruits. Examples of such insects are locust, variegated grasshopper, beetle etc.

Boring insects: They possess short snout with chewing mandibles for boring into plants. They feed on plant tissues and attack stored grains. Example of boring insects are stem borers and weevils.

Nature of damage done by crop plant pests

The degree of damage of crops by pests differ from one crop to another. Some of the damage done by crop pests include;

  1. Sucking of sap from leaves.
  2. Reducing grains to powder.
  3. Mottling or loss of leaves.
  4. Yellowing of leaves (Chlorotic patches).
  5. Transmission of fungal and viral diseases.
  6. Death of young shoots or stunted/stopped growth.

Effects of crop pests on crop yield

Crop pests eat up leaves of plants thereby reducing photosynthesis (the process by which green plants make their food).

They create wound on the stems which are source of secondary infections.

They suck saps from leaves, fruits and seeds causing distortion and stunted growth.

They bore holes into grains reducing its market value.

They introduce toxin which affect plants growth.


Define crop pests.

Mention five (5) examples of insect pests.