Greenhead Horse Fly:

The greenhead horse fly is a large, aggressive biting fly commonly found in coastal regions during summer. Females feed on the blood of mammals, including humans, using powerful mouthparts to pierce skin. Males feed on nectar and plant juices. Their larvae develop in moist soil and mud, preying on small invertebrates. Greenhead horse flies are strong fliers and can follow prey for long distances, making them a nuisance for beachgoers and outdoor workers. While their bites are painful, they are not known to transmit diseases to humans in North America.