What is a distinguishing feature of Horse Flies?

The distinguishing feature of horse flies is that only females bite. This behavior is critical for their reproductive process, as female horse flies require blood meals to develop their eggs. They possess specialized mouthparts that enable them to pierce the skin of their hosts and feed on blood. Male horse flies, on the other hand, primarily feed on nectar and do not have the same biting capability.

The other options do not accurately represent key characteristics of horse flies. For instance, horse flies are generally larger than house flies, not smaller. They also do not have particularly colorful patterns; rather, they typically exhibit more subdued colors and patterns. Additionally, horse flies can be found in a variety of environments, not limited to urban areas, but also in rural and wild habitats. Hence, the correct choice highlights the unique feeding behavior of female horse flies.