Gadfly of Sheep
The Gadfly of the sheep lays its eggs in the nostrils of the sheep. There, the maggots hatch and live in the frontal sinuses until fully grown, they then drop to the ground and bury themselves. After pupation, they emerge as flies. This illustration is natural size and shows a Gadfly larvae.
John H. Finley ed. Nelson's Perpetual Loose-Leaf Encyclopaedia (vol. 5) (New York, NY: Thomas Nelson and Sons, 1917)