The diagrams below illustrate pests of crops. Study them and answer the questions that follow.
(a) Name each of the pests labelled I, II and III.
(b) Describe the life cycle of the pest labelled I.
(c) State four damages caused by the pest labelled III on crops.
(d) Enumerate four ways of controlling the pest labelled IV.
Explanation
(a) Name of pests
I Grasshopper
II Weevil
III Cotton stainer
(b) Life cycle of the pest labelled I (Grasshopper)
- The female lays eggs on the underside of leaves/ dig hole in the soil / decaying wood;
- The eggs hatch into nymphs;
- The nymphs move to farms and feed on cassava leaves or other shrubs till they become adults;
- The nymph moults five times before becoming adult grasshopper;
- It undergoes incomplete metamorphosis.
(c) Damages caused by the pest labelled III (Cotton stainer) on crops
- Transmits diseases;
- Causes leaf distortion;
- Pierces and sucks sap from crop tissues;
- Reduces the quality of bolls;
- Produces saliva which is toxic to crops;
- Wounds caused by the pest to plants leads to secondary infection.
(d) Ways of controlling the pest labelled IV (Bird)
- Use of avicides;
- Drumming or noise making on the farm;
- Use of cage traps;
- Use of scarecrow or bird scarers;
- Shooting with catapult/sling;
- Fencing/screening farms in greenhouse;
- Destruction of the birds’ nests