Pests of Crops

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We are eager to have you join us !!

In today’s Agricultural Science class, We will be learning about Pests of Crops. We hope you enjoy the class!


crop pests agric classnotesng



  • Meaning of crop pest
  • Types of crop pest
  • Classification of insect pest



A crop pest can be defined as any organism capable of causing damage to the crop.


Important crop pest are grouped into the following classes;

  1. Insects
  2. Birds
  3. Rodents
  4. Monkeys
  5. Man
  6. Nematodes



  1. Biting and chewing insects: they possess strong mandible and maxillae (mouthparts) which enable them to bite and chew plant parts e.g. termites, grasshoppers, leafworm, mantids, locusts and beetles.
  2. Piercing and sucking insects: they possess strong mouthparts called a proboscis which enable them to pierce through plants and suck liquid materials from them. Examples are aphids, cotton strainers, mealy bugs, scale insects, capsids, mirids and whiteflies.
  3. Burrowing insects: they and their larva stage are capable of burrowing the tissue of the plant parts or fruits or seeds. Examples are bean beetles, stem borers, maize weevils and rice weevils.



  1. What are crop pests?
  2. List the three classes of insect pests.


crops plant form



Pest Crops Attacked Natures of Damages and Economic Importance Prevention and Control Measures
Stem burrower Cereals e.g. rice, maize, guinea corn. (i)     Larvae bore-holes into stems

(ii)    They eat up the tissues

(iii)   They weaken the plant

(i)     Uproot and burn infected plant

(ii)    Spray with insecticides e.g. Gammalin 20

(iii)    Reduced growth and yield

(iv)  Early planting

(v)   Crop rotation

Army Worm Cereals e.g. maize (i)     Larvae invade and eat up leaves and stem

(ii)    Reduce photosynthesis

(iii)   Retarded growth

(iv)  Reduced yield

(i)     Hand-picking

(ii)    Spray with insecticides. E.g. DDT


Pod burrower Legumes e.g. cowpea, soybeans (i)     Larvae bore into the pod

(ii)    They eat up the seeds

(iii)   Reduced yield

(i)     Crop rotation

(ii)    Early harvesting

(iii)    Spray with insecticides

(iv)  Introduce diseases.

Aphids Legumes e.g. cowpea, soybeans (i)     Stunted growth

(ii)    Galls on leaves

(iii)   Vectors of disease e.g. rosette, mosaic disease of cowpea

(i)     Spray with insecticides to kill the vector

(ii)    Uproot and burn infected plant


Leaf beetle Legumes e.g. cowpea, soybeans (i)     They eat up the leaves

(ii)    Reduce photosynthesis

(iii)   Reduced yield

(i)     Spray with insecticides

(ii)    Use pest-resistant varieties.

Cocoa mirids (capsids) Beverages e.g. Cocoa (i)     They inject toxic saliva into the plant

(ii)    Transmits fungal diseases

(iii)   Reduced yield

(iv)  Stunted growth

(i)     Spray with insecticides e.g. Gammalin 20

(ii)    Regular Weeding

Yam beetles Tubers e.g yam (i)     Boreholes into yam tubers

(ii)    Reduced yield

(iii)   Reduction in quality and market value

(i)     Dust yam setts with Adrin dust before planting

(ii)    Crop rotation

Cassava Mealybugs Tubers e.g cassava (i)     Twisting of the stem and reduced internodes

(ii)    Swelling of shoots

(iii)   Reduced yield

(i)     Early planting

(ii)    Use pest-resistant varieties.

(iii)   Cutting treatment

(iv)  Spray with insecticides

Green Spider mite Tubers e.g cassava (i)     They feed on the leaves

(ii)    Reduce the rate of photosynthesis

(iii)   Reduced yield

(i)     Use biological control

(ii)    Spray with insecticides

Variegated Grasshopper Tubers e.g Cassava, yam (i)     Adults and larvae eat up the leaves and stem

(ii)    Reduce the rate of photosynthesis

(iii)   Reduced growth

(iv)  Reduced yield

(i)     Hand-picking

(ii)    Spray with insecticides e.g. Adrex 40

Cotton Stainer Cotton (i)     They pierce and suck sap from plants

(ii)    Produce toxic saliva

(iii)   Transmit diseases

(iv)  Reduce the quality of boll

(v)    Leaf distortion

(i)     Hand-picking

(ii)    Spray with insecticides

Cotton bollworm Cotton (i)     Larvae feed on the seed of cotton

(ii)    Crop rotation

(iii)   Destroy the lint and reduce its quality

(iv)  Premature fall of cotton boll

(i)     Spray with insecticides to kill insects

(ii)    Burn cotton plant debris after harvesting.

Thrips Vegetables e.g. Onion, tomato (i)   Browning of leaves

(ii)  Wilting of plant

(iii) Reduced yield

(i)     Spray with insecticides
Leaf rollers Vegetable (i)   Rolling and twisting of leaves

(ii)  Reduction in the rate of photosynthesis

(iii) Reduced yield

(i)     Spray with insecticides e.g. Vetox 85
Leaf beetle Vegetables e.g. pepper, okra and tomato (i)   They eat up leaves and stems

(ii)  Reduced photosynthesis

(iii)  Reduction in yield and quality

(iv)  Spray with appropriate insecticides e.g. Vetox 85
Bean beetle, grain weevils Stored produce e.g. rice, cowpea and maize. (i)   Boreholes into grains and eat them up

(ii)  Reduce the quality of stored produce

(iii) Reduced farmer’s income

(iv)Reduce the market value of grains

(v) Reduce the viability of infested grains

(i)       Early harvesting

(ii)      Proper storage of produce

(iii)     Proper cleaning and fumigation of the store with phostoxin tablets or with lindane dust.

(iv)    Store grains over fireplaces

(v)     Proper drying of seeds to reduce moisture content and kill the eggs and larva of pests.

Birds Rice, maize, millets and sorghum (i)   Feed on grains in the field

(ii)  Reduction in quality and yield

(iii) Reduction in the income of farmers

(i)       Use of bird scarer or scarecrow

(ii)      Use of cage traps with baits

(iii)     Shooting with catapult

(iv)    Drumming or noise making on the farm

(v)     Use of explosive mechanism at regular intervals

(vi)    Use of avicides

(vii)   Fencing /Screening farms in greenhouse

Rodents e.g. bush rabbit, rats and squirrel Rice, yam, cassava and fruits (i)     They feed on crops

(ii)    Destroy the whole plant

(iii)   Reduction in yield

(iv)  Increase in cost of production

(i)       Trapping with braits.

(ii)      Use of rodenticides

(iii)     Use of string/wire traps

(iv)    Use of predators e.g. dogs and cats

(v)     Clean weeding of farms

(vi)    Shooting and fencing

(vii)   Use of pit traps

Monkeys Cocoa mango, banana, and orange (i)     They eat up the fruits

(ii)    Reduce the quality of fruits

(iii)   Losses to the farmer

(i)       Use traps

(ii)      Shooting with a gun where possible.



  1. List two ways of controlling cocoa mirids
  2. List two ways of controlling monkeys



We have come to the end of this class. We do hope you enjoyed the class?

Should you have any further question, feel free to ask in the comment section below and trust us to respond as soon as possible.

In our next class, we will continue learning about Pest of Crops. We are very much eager to meet you there.


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