Which of the following insects has a biting mouthpart?

The deer fly is characterized by its biting mouthparts, which are adapted for piercing the skin of mammals to obtain blood. This feeding behavior is linked to its role in the ecosystem, as it serves as both a predator and a blood-feeding insect, which can also impact livestock and humans due to its potential to transmit diseases.

In contrast, the house fly has sponging mouthparts that allow it to dissolve food substances and suck them up, while butterflies possess a long proboscis designed for sipping nectar, not biting. Ladybugs, which are known for their beneficial role in controlling aphid populations, also have chewing mouthparts but not in the same context as a biting insect like the deer fly. The distinct structure and function of the mouthparts in these insects explain why the deer fly is the correct answer in this scenario.