Which of the following insects is known to have piercing-sucking mouth parts?

Aphids are indeed recognized for having piercing-sucking mouthparts, which are specialized for extracting fluids from plants. These mouthparts are adapted to penetrate plant tissues and suck out the sap, making aphids sap-suckers. This feeding method can lead to significant damage to plants, as aphids not only deplete nutrients but can also transmit plant viruses.

In contrast, caterpillars possess chewing mouthparts that allow them to munch on plant leaves and other plant material. Beetles also have chewing mouthparts, suited for gnawing and breaking down tough materials. Grasshoppers similarly have chewing mouthparts enabling them to feed on a variety of plant types by tearing the foliage apart rather than sucking fluids. This distinction highlights the specialized feeding adaptations of different insect groups and underscores why aphids are categorized specifically for their piercing-sucking function.