Which of the following insects have piercing mouthparts?

Fleas are known for having piercing mouthparts that are specifically adapted for feeding on the blood of their hosts. These mouthparts consist of a specialized structure that allows them to penetrate the skin of mammals and birds, which is essential for their survival and reproduction. Fleas use these mouthparts to effectively extract blood, which provides them with the necessary nutrients.

In contrast, house flies have sponging mouthparts used for soaking up liquid food, butterflies have a proboscis designed for sipping nectar, and beetles typically have chewing mouthparts suitable for grinding food. Each of these insects has mouthparts that are adapted to their feeding habits, but only fleas possess the piercing mouthparts necessary for blood feeding. This adaptation is a significant feature that distinguishes fleas from the other insects listed.