Dundas island blackfly

Dundas island blackflies, also known as the flesh-eating flies, are an insect native to Dundas Island in Canada. Natives near the area refuse to go to the island out of fear. They grow to 5-6 inches in length and are colored black, save for the head, eyes, and tip of the abdomen. They don't only eat their prey's flesh, they also drink its blood. They will hunt for hours, and won't give up, unless their prey leaves the island. They are also venomous enough to kill a cow.