Which of the following insect pests causes defoliation in crops?

The correct answer is grasshopper. Grasshoppers are known to be destructive pests that feed on the leaves and stems of plants, causing severe defoliation in crops. They can also cause damage to fruits and flowers. While the other options can also be damaging to crops, they do not specifically cause defoliation. - Mirids are known for sucking the sap of plants, which can cause yellowing, wilting, and stunted growth of leaves and stems. - Weevils are known for feeding on seeds, nuts, and fruits, and can cause damage to crops such as maize, soybeans, and cotton. - Aphids are also known for sucking the sap of plants, causing curling and yellowing of leaves, as well as stunted growth.