How do horse flies differ from flower-feeding members of their family?

Within the family Tabanidae (order Diptera), horse flies are distinguished from many of their relatives by their specialized feeding habits and mouthpart structure. While many primitive genera within this family feed exclusively on flowers, horse flies—specifically the females of genera such as Tabanus, Chrysops, and Haematopota—are known for being bloodsuckers that act as pests to humans and animals.12

The primary differences include:

• Mouthparts: Horse flies possess specialized, serrated mandibles and maxillae that function as blades to cut through the skin and blood vessels of a host. In contrast, flower-feeding members of the order Diptera typically rely on mouthparts adapted for imbibing nectar, pollen, or other exposed fluids.34
• Dietary Needs: While male horse flies feed on nectar, honeydew, and plant sap, the females require blood meals to mature their eggs. Many other dipteran families, such as hover flies, feed primarily on nectar and pollen throughout their adult lives, playing a significant role in pollination.142
• Larval Habits: The larvae of horse flies also differ in their ecological roles; for instance, Tabanus and Haematopota larvae are carnivorous, whereas those of Chrysops (deer flies) are vegetarian.2