Which insect pest damages plants by sucking sap?

• A. Lady beetle
• B. Scale insect
• C. Cabbage moth
• D. Whitefly

Answer: (B)

Sap-sucking insects feed by inserting their piercing-sucking mouthparts into plant tissues and drawing out the plant’s fluids. Scale insects are a classic example of this feeding style: they attach firmly to stems or leaves, appear as tiny shell-like coverings, and continually drain sap. This direct feeding weakens the plant, often causing yellowing, stunted growth, and poor vigor. They also excrete honeydew, which can lead to sooty mold that further reduces photosynthesis and plant health.

The other options align with different feeding habits. Lady beetles are beneficial predators that eat pests rather than plant tissue. The cabbage moth is a chewing insect; its larvae strip or skeletonize leaves by munching rather than piercing to suck sap. Whiteflies do feed by sucking sap as well, but scale insects are the most typical example of a sap-sucking pest among these choices, making them the best answer for this question.