This creature looks like an 8-foot long hairy, black fly.
Giant Horsefly CR 3
Environment temperate or warm forests and marshes
Organization solitary, pair or nest (10–20)
Giant horseflies are aggressive relatives of the smaller horsefly and generally frequent the same type of habitat. Their lairs are always built near a source of water and the lair itself is kept damp by water from the surrounding ground. A typical nest contains one female and up to 20 males. One male is taken as a mate and during the spring or fall months, the female lays a clutch of 5–8 eggs. During warmer months or when the temperature is extremely high, a flurry of activity can be noticed around the nest as the horseflies prepare for the colder months and the female prepares to lay her eggs. Young hatch within a few weeks and resemble giant larvae with segmented bodies. Each segment of the larvae’s body has small protuberances that aid in movement.
Giant horseflies sustain themselves on a diet of nectar, pollen, and blood. Their hunting territory typically covers a range of several square miles around their nest. Blooded targets usually involve animals, livestock, and the occasional humanoid.
Giant horseflies look like large, black hairy flies. Their bodies are thick and their multifaceted eyes are black and dark gold. Wings are translucent and their legs are long, bristly and jet black. Females have a slightly longer mouth tube than males.
Giant horseflies attack by delivering a painful bite to their opponent. If hunting, a giant horsefly attempts to grapple its foe and drain its blood. Slain prey is left to rot; the giant horsefly only drinks its blood, it does not eat its remains.
Giant Horsefly from the Tome of Horrors Complete, Copyright 2011, Necromancer Games, Inc., published and distributed by Frog God Games; Author Scott Greene.