Agricultural Science

Meaning of crop pest

A pest can be described as any organism capable of causing damage to crop plant.

Types of Crop Pest.

Important pests of crop plants are grouped into the following classes:

(i) insect;  (ii) birds;  (iii) rodents;  (iv) monkeys;  (v) man;  (vi) nematodes


Insects pests can be classified into various groups based on their mode of feeding.  These groups of insect pest include:

  1. Bitting and chewing insects;
  2. Piercing and sucking insects;
  3. Boring insects.
  4. Biting and Chewing Insects: These insect (mouth-parts) which enable them to bite and chew plant    Examples include: termites, grasshoppers, leaf worms, army worms, mantids, locust, beetles, etc.
  5. Piercing and sucking insects: These insect pests posses strong mouthparts called proboscis stuck liquid from materials from plants’ tissues.  Examples include aphids, cotton strainers, mealy bugs, scale insects, capsids or mirids, white flies, etc.
  6. Burrowing insects: These insects including their larvae are capable of burrowing into plant parts and destroying the tissues of the plant or fruits or seeds.  Examples include: bean beetles, stem burrowers, maize weevils and rice weevils.


Insect PestCrops AttackedNature of Damage and Economic ImportancePrevention and Control Measure
Stem burrowerCereals e.g. rice, maize, guinea corn    i.       Larvae bore holes into stems.ii.      They eat up the plantiii.       They weaken the plantiv.       Reduced growth and yield    i.       Uproot and burn infected plant.ii.      Spray with insecticides e.g. Gammlin 20.iii.       Early plantingiv.       Crop rotation.
Army WormCereals e.g. maize    i.       Larvae invade and eat up leaves and stemii.      Reduce photosynthesisiii.       Retarded growthiv.       Reduced yield    i.       Hand pickingii.      Spray with insecticides e.g. DDT. 
Pod BurrowerLegumes e.g. cowpea, soyabeans    i.       Larvae bore into the pod.ii.      They eat up the seeds.iii.       Reduced yieldiv.       Introduce disease    i.        Crop rotationii.      Early harvestingiii.       Spray with insecticides
AphidsLegumes e.g cowpea, soyabeans    i.       Stunted growthii.      Galls on leavesiii.       Vectors of disease e.g. rosette, mosaic disease of cowpea    i.       Spray with insecticides to kill vectorii.      Uproot and burn infected plant 
Leaf beetleLegume e.g. cowpea soyabeans    i.       They eat up the leavesii.      Reduce photosynthesisiii.       Reduced yield    i.       Spray with insecticidesii.      Use resistant varieties 
Cocoa mirids (capsids)Beverages e.g. cocoa    i.       They inject toxic saliva into plantii.      Transmit fungal diseasesiii.       Reduced yieldiv.       Stunted growth    i.       Spray with insecticide e.g. Gammalin 20ii.      Regular weeding
Yam beetlesTubers e.g. yam    i.       Bore holes into yam tubersii.      Reduction in yieldiii.       Reduction in quality and market value    i.       Dust yam sets with Adrin dust before plantingii.      Crop rotation
Cassava mealybugsTubers e.g. cassava    i.       Twisting of stem and reduce internodesii.      Swelling of shootsiii.       Reduced yield    i.       Early plantingii.      Use resistant varietiesiii.       Cutting treatmentiv.       Spray with insecticides
Green spidermiteTuber e.g. cassava    i.       They feed on the leavesii.      Reduce rate of photo synthesisiii.       Reduction in yield    i.       Use biological controlii.      Spray with insecticides.
Variegated grasshopperTubers e.g. cassava, yam    i.       Adults and larvae eat up the leaves and stemii.      Reduce the rate of photosynthesisiii.       Reduced growthiv.       Reduced yield    i.       Hand pickingii.      Spray with insecticides e.g. Adrex 40.
Cotton stainerCotton    i.       They pierce and suck sap from plants.ii.      Produce toxic salivaiii.       Transmit diseases.iv.       Reduce quality of bollv.      Leaf distortion    i.       Hand pickingii.      Spray with insecticides.
Cotton bollwormCotton    i.       Larvae feed on the seeds of cottonii.      Crop rotationiii.       Destroy the lint and reduce its qualityiv.       Premature fall of cotton boll.    i.       Spray with insecticides to kill insects.ii.      Burn cotton plant debris after harvesting.
ThripsVegetables e.g. onion, tomato    i.       Browning of leavesii.      Wilting of plantiii.       Reduced yield    i.       Spray with insecticides.
Leaf rollers Leaf beetleVegetable Vegetables e.g. pepper, okro, tomato    i.       Rolling and twisting of leaves.ii.      Reduction in rate of photosynthesis.iii.       Reduce yieldiv.       They eat up the leaves and stemsv.      Reduced photosynthesisvi.       Reduction in yield and qualitySpray with insecticides e.g. Vetox 85. Spray with appropriate insecticides e.g. Vetox 85
Bean beetle, grain weevilsStored produce e.g. rice, cowpea, maize    i.       Bore holes into grainsand eat them up.ii.      Reduce the quality of stored produceiii.       Reduce quality of grains to powderiv.       Reduce farmer’s incomev.      It reduces the market value of grainsvi.       It reduces viability of infested grains.    i.       Early harvestingii.      Proper storage of produceiii.       Proper cleaning and fumigation of store with phostoxin tablets or with lindane dustiv.       Store grains over fire placesv.      Proper drying of seeds to reduce moisture content and kill the eggs and larva of pest.
BirdsRice, maize, millets, sorghum    i.       Feed on grains in the fieldii.      Reduction in quality and yieldiii.       Reduction in income of farmer    i.       Use of bird scarer or scare cow.ii.      Use of cage traps with baitsiii.       Drumming or noise making on the farmiv.       Shooting with catapultv.      Use of explosive mechanism at regular intervalsvi.       Use of avicidesvii.      Fencing/screening farms in greenhouse.
Rodents e.g. bush rabbit, rats, squirrelRice, yam, cassava, fruits    i.       They feed on cropsii.      Destroy whole plantsiii.       Reduction in yieldiv.       Increase in cost of production    i.       Trapping with baitsii.      Use of rodenticidesiii.       Use of string/wire tapesiv.       Use of predator e.g. dogs and catsv.      Clean weeding of farmsvi.       Shooting and fencingvii.      Use of pit traps.
MonkeysCocoa, mango, banana, orange.    i.       They eat up the fruitsii.      Reduce the quality of fruitsiii.       Losses to the farmer    i.       Use trapsii.      Shooting with gun where possible


  1. Insects pest destroy crops in the field through their biting, chewing, boring, sucking and defoliation activities
  2. They cause reduction in viability of stored produce
  3. Spot of injuries by insets may predispose crops to disease attact.
  4. They increase the cost of production during the course of controlling them
  5. They render vegetables and fruits unattractive and unmarketable
  6. Some are carriers or vectors of diseases.
  7. The profits of farmers are reduced
  8. They reduce the quality of produce either in the store or in the field
  9. They generally reduce the yield of crops
  10. They can also cause total death of crop plants.

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